The Integration of a Manufacturing and Assembly...

The Integration of a Manufacturingand Assembly Cell

Manufacturing Senior Design TeamProject Manager: Emily Olney, BS/MS ISEGroup Members: Seth Abbe, ISE

Andrew Astry, ISE Antoine Aveline, MEJohn Nuszkowski, MERakesh Patel, ISEDale Pluss, EE

Contact Information:Team Manager: Emily [email protected] FolderLouise M. Slaughter Building (78)2nd FloorRochester Institute of TechnologyRochester, NY 14623-5604

The Integration of a Manufacturing & Assembly Cell 2 of 86

Abstract

This report presents an overview of the process through which the design team took to

integrate a manufacturing and assembly production cell. Integrated manufacturing and assembly

cells are commonly used in many industrial areas because of their ability to maximize efficiency

and eliminate ergonomic problems that arise in manual operations. The manufacturing and

assembly cell involved in this project consists of a conveyor belt, two robotic arms, and a CNC

milling machine. The project involves not only getting each machine to function properly on its

own, but also integrating each piece of equipment with the other. When the cell has been fully

integrated, it will be able to perform an entire manufacturing process automatically.

The design team chose a product to manufacture in the cell based on a variety of

customer and project requirements. The product to be built in the cell was determined through a

formal concept development process, which involved brainstorming, generating a short list of

possible products, and then using a group drawing method. After the product was determined

the team began engineering how the cell will function. The integrating of the cell is handled

with the use of a programmable logic controller, also known as a PLC. Sensors placed at various

locations in the cell allow the PLC to know where each piece of equipment or material is during

each step of the manufacturing or assembly process. This will allow all of the machines to work

closely together and create the finished product. Multiple grippers and fixtures were also

designed and built by the team to incorporate the specific product being manufactured in the cell.

Once the cell has been completed it will be used as a demonstration tool for tours and future

students of the Industrial and Systems Engineering Department at Rochester Institute of

Technology.

© Abbe, Astry, Aveline, Nuszkowski, Olney, Patel, Pluss, May 2003


Table of Contents

A. IntroductionAbstract.................................................................................................................................................2A. Introduction.....................................................................................................................................31 Recognize and Quantify the Need ...................................................................................................6

1.1 Needs Assessment......................................................................................................................6Project Goal......................................................................................................................................6

The Response is: Category 4. New Problem, No Process or Product...................................91.2 Formal Statement of Work......................................................................................................10

2 Concept Development.....................................................................................................................112.1 Brainstorming Technique........................................................................................................112.1.1 Short List Generation...........................................................................................................112.2 Group Drawing Method..........................................................................................................132.3 Empathy Method......................................................................................................................132.4 Product Selection.....................................................................................................................14

3 Feasibility Assessment....................................................................................................................153.1 Adhesive Assembly.................................................................................................................163.2 Set Screw Assembly................................................................................................................203.3 Radar Chart..............................................................................................................................24

4 Design Objectives and Performance Specifications......................................................................254.1 Design Objectives....................................................................................................................254.2 Performance Specifications.....................................................................................................26

5 Analysis of Problems and Synthesis of the Design.......................................................................275.1 Industrial Analysis...................................................................................................................27

5.1.1 Process Flow & Task Allocation.....................................................................................27Figure 2: Process Flow Diagram..............................................................................................285.1.2 Limitations of the Cell......................................................................................................295.1.3 Quality Function Deployment..........................................................................................30

5.2 Mechanical Analysis................................................................................................................315.2.1 The CNC Vise...................................................................................................................315.2.2 Robotic Grippers...............................................................................................................33

5.2.2.1 Aluminum Base Part Gripper Design.......................................................................345.2.2.2 Pen Holder Gripper Design.......................................................................................36

5.2.3 Fixture Design..................................................................................................................375.2.3.1 Aluminum Base Feeder.............................................................................................375.2.3.2 Pen Holder Swivel Feeder........................................................................................385.2.3.3 Pallet Cradle..............................................................................................................39

.........................................................................................................................................................

....................................................................................................................................................395.3 Electrical Analysis...................................................................................................................40

5.3.1 Robots...............................................................................................................................445.3.2 Milling Machine...............................................................................................................475.3.3 System Feedback..............................................................................................................475.3.4 Software............................................................................................................................47

6 DFX Analysis..................................................................................................................................496.1 DFX Definitions......................................................................................................................49

6.1.1 Design for Usability.........................................................................................................496.1.2 Design for Assembly........................................................................................................50



6.1.3 Design for Remanufacturing and Design for the Environment.....................................506.1.4 Design for Manufacturing................................................................................................516.1.5 Design for Disassembly...................................................................................................516.1.6 Design for Reliability.......................................................................................................516.1.7 Design for Safety..............................................................................................................526.1.8 Design for Cost.................................................................................................................526.1.9 Design for Material Handling..........................................................................................526.1.10 Design for Aesthetics.....................................................................................................53

6.2 Product Design.........................................................................................................................536.2.1 Design for Manufacturability...........................................................................................53 6.2.2 Design for Assembly.......................................................................................................536.2.3 Design for Disassembly...................................................................................................546.2.4 Design for Usability.........................................................................................................546.2.5 Design for Aesthetics.......................................................................................................55

6.3 CNC Vise Design.....................................................................................................................556.3.1 Design for Safety..............................................................................................................556.3.2 Design for Usability.........................................................................................................556.3.3 Design for Reliability.......................................................................................................566.3.4 Design for Adaptability....................................................................................................56

6.4 Fixture Design..........................................................................................................................576.4.1 Aluminum Blank Part Feeder..........................................................................................57

6.4.1.1 Design for Reliability................................................................................................576.4.1.2 Design for Manufacture............................................................................................576.4.1.3 Design for Cost..........................................................................................................586.4.1.4 Design for Material Handling...................................................................................59

6.4.2 Pen Holder Swivel Feeder................................................................................................596.4.2.1 Design for Cost..........................................................................................................596.4.2.2 Design for Useability................................................................................................596.4.2.3 Design for Reliability................................................................................................59

6.4.3 Pallet Cradle......................................................................................................................606.4.3.1 Design for Reliability................................................................................................606.4.3.2 Design for Cost..........................................................................................................60

6.5 Gripper Design.........................................................................................................................606.5.1 Aluminum Base Part Gripper...........................................................................................60

6.5.1.1 Design for Cost..........................................................................................................616.5.1.2 Design for Safety.......................................................................................................616.5.1.3 Design for Reliability................................................................................................61

6.5.2 Pen Holder Gripper...........................................................................................................616.5.2.1 Design for Safety.......................................................................................................616.5.2.2 Design for Cost..........................................................................................................616.5.2.3 Design for Reliability................................................................................................62

7 Detailed Discussion of Cell............................................................................................................637.1 First Station..............................................................................................................................63

7.1.1 Pick-and-Place Robot ......................................................................................................647.1.2 Pick-and-place Robotic Gripper......................................................................................667.1.3 Aluminum Blank Parts Feeder.........................................................................................677.1.4 CNC Mill...........................................................................................................................687.1.5 Pneumatic Vise.................................................................................................................717.1.6 Pallet Cradle......................................................................................................................727.1.7 Finished Goods Bin..........................................................................................................72



7. 2 Second Station........................................................................................................................74 ...................................................................................................................................................747.2.1 Assembly Robot...............................................................................................................747.2.2 Pen Holder Robotic Gripper............................................................................................757.2.3 Pen Holder Fixture...........................................................................................................76

7.3 Electrical Aspects of Cell........................................................................................................777.3.1 Discussion of Programmable Logic Controller (PLC)...................................................777.3.2 Interfacing Issues..............................................................................................................787.3.3 Programming Issues.........................................................................................................79

8 Simulation Model............................................................................................................................819 Recommendations for Optimization..............................................................................................8410 Conclusion.....................................................................................................................................85



1 Recognize and Quantify the Need

In order to generate a solution to a problem, the problem must first be identified. It isimportant to determine what the existing need is and also assess how great the need is. Byparticipating in this facet of the design process, the group will obtain an understanding of theproblem as well as verify that they are thinking along the same lines as the customer. Thefollowing Needs Assessment and Formal Statement of Work define the project at hand.

1.1 Needs Assessment

Project GoalThe present goal of this project is to create a cell that can manufacture and assemble a productdesigned by the team. The long-term goal of the project is to use the completed cell as ademonstrative tool for tours and prospective students as well as a teaching tool in future classesof the Industrial and Systems Engineering course 03-03-525-01. The manufacturing andassembling of the defined product will aid in illustrating the technology that RIT can offer aswell as the projects that the students will participate in.

Project Mission Statement

The mission of this design project team is to integrate a manufacturing and assembly cell thatwill produce an engraved desktop pen holder. Once completed, the functioning cell will be usedas a teaching tool in several Industrial and Systems Engineering courses as well asdemonstrations on tours.

Product Description

The cell will be designed to manufacture and assemble a desktop pen holder. The base of theproduct will be aluminum and engraved with ‘RIT.’ Two metal, swivel, funnel pen holders willbe assembled onto the base. The cell contains a friction powered conveyor belt, a CNC millingmachine, robots, and possibly, manual operations.

Scope Limitations

The system should include a conveyor, robots, a computer controlled milling machine, and oneor more manual/automated assembly stations.

Hardware requirements should include, but are not limited to, various fixtures, robotic grippers,and part holding devices to be designed and fabricated. Therefore, the team requires access tomaterials and machine shop facilities necessary to fabricate these components.

Software requirements should include, but are not limited to, integrating an array of sensors,programming the individual pieces of equipment (robots, milling machine, etc.), and an overallcell control computer to integrate all functions. Therefore, the team requires access to varioussensors for cell communication, and to SYSWIN 34 and Omron PLC control software for cellintegration and control.

Stakeholders



At the present time, the stakeholders are the faculty members of the Industrial and SystemsEngineering Department at RIT. However, in the future, the students of the Industrial andSystems Engineering Department at RIT will also become stakeholders.

Key Business Goals

The integration of a manufacturing and assembly cell will be of great benefit to the Industrial andSystems Engineering Department at RIT. The cell can and will be used in several ways:

• As a teaching tool in the course 03-03-525-01, Manufacturing Engineering, taught in theISE department.

• As a teaching tool in the other courses taught in the ISE department as the departmentdeems appropriate.

• As an exhibit for tours of prospective students including the students enrolled in RIT’sundeclared engineering program.

• As a base for future projects in the ISE department.

Top Level Critical Financial Parameters

The following parameters describe the critical financial parameters related to the cell.

• The preferred software used to program the machines would be one that the Industrialand Systems Engineering Department currently uses.

• The team shall require a budget for any hardware or software purchases that arenecessary for the successful completion of the project.

Financial Analysis

The following parameters describe the dominant issues related to the cell design.

• The estimated budget for the project is $1500.

Primary Market

The primary market for the manufacturing and assembly cell is the Industrial and SystemsEngineering Department at RIT. This includes both the faculty and students. At the currenttime there are 11 faculty members and approximately 130 students.

Secondary Markets

Secondary markets initially include other engineering disciplines at RIT and potentially otherdepartments outside of the Kate Gleason College of Engineering. Markets outside of RIT are notto be considered for the scope of this design team.

Critical Performance Parameters (Order Qualifiers, Minimum Required Performance)



• Produce an engraved desktop pen holder.• Simple programming of the machines for ease of use.• Longevity so it can be used for many classes.

Critical Performance Parameters (Order Winners, Desired Performance)

• Flexibility of the cell so that it can be used for demonstrations.• Flexibility of the cell so that it can be altered to produce a different product in the future.• Design and build a product that can be given to prospective students on their tour of RIT

and the Brinkman Lab.

Innovation Opportunities

• Designing the manual/automatic stations• Designing robotic grippers• Designing the product

Background Research

Describe the NeedThere exists a need to integrate a manufacturing and assembly cell in theBrinkman Lab at RIT to produce some widget. The cell should include the use ofa conveyor, robots, a computer controlled milling machine, and one or moremanual/automated assembly stations. The product should be comprised of metaland/or plastic components. Along with the cell, the allocation of tasks, a processflow diagram, and complete cell specifications must be provided to the customer.The team shall also design and fabricate appropriate fixtures and robotic grippers,develop and integrate the sensor array and cell computer, and integrate thehardware components of the cell via cell computer.

The cell shall operate and be capable of being prepared as a case study for theIndustrial and Systems Engineering course 03-03-525-01.

Categorize the Need After the problem at hand has been defined and the need established, the need canbe placed in one of six categories. Each category establishes in generic termswhat type of problem is being examined and the potential solution. Types of Problem:

• Old Problem• New Problem• No Problem

Types of Solutions:• Existing Process or Product• No Process or Product



• New Technology

This particular project is defined in these terms below.

The Response is: Category 4. New Problem, No Process or Product

Manufacturing and assembly cells do exist for other products. However, there isnot one that is currently designed to match the desktop pen holder that should beproduced using the particular equipment constraints previously identified.

ConstraintsA budget of $1500 for any hardware or software purchases that are necessary forthe successful completion of the project.

The three stations of the cell cannot be moved. However, the team may determinewhat operations occur at each station within the constraints of each individualstation. For instance, the CNC milling machine is located next to a robot, but apick-and-place is not currently feasible because the clamping/unclampingoperations of the mill are not automated. A pneumatic clamp will have to bedesigned and built or purchased to utilize the robot as a pick-and-place. Theconveyor is only capable of moving in one direction. The robotic arms can bemoved, assuming there is a cable long enough to connect it to the necessarycomputer.



1.2 Formal Statement of WorkThe student design team shall develop the hardware and software necessary to fully integrate amanufacturing and assembly cell in the Brinkman Lab. The components of the system shouldinclude a conveyor, robots, a computer controlled milling machine, and one or more manual /automated assembly stations. The team shall also design a product that will include metal and/orplastic parts. The product shall utilize all the components of the system previously defined.Hardware requirements shall include various fixtures, robotic grippers, and part holding devicesto be designed and fabricated. Software should include integrating an array of sensors,programming the individual pieces of equipment (robots, milling machine, etc), and an overallcell control computer to integrate all functions.

In addition, the team shall…

• Develop an overall cell design including allocation of tasks, process flow diagram,and complete cell specifications.

• Design and fabricate appropriate fixtures.

• Design and fabricate appropriate robotic grippers.

• Develop and integrate the sensor array and cell computer.

• Integrate the hardware components of the cell via cell computer.

• Prepare a written report (consisting of a complete technical data package), technicalarticle, conference and poster presentations of results.

• Copies of all software developed, with source code, and a user’s manual. outlining thetheory and operation of the simulation tool.

• Demonstrate the operating cell and prepare as a case study.

Agreed

By _____________________________________ Date ______________ (Project Team Manager)

By _____________________________________ Date ______________ (Design Team Members)






By _____________________________________ Date ______________ (Customer Rep/Faculty Mentor)

By _____________________________________ Date ______________ (Customer Rep/Faculty Mentor)



2 Concept Development

In order to develop a manufacturing and assembly cell, we need to first design a product

to build in the cell. Therefore, some of the concept development techniques were used to

determine a product to build. The process that was followed, as well as the criteria that were

used to base decisions on at each step are outlined below.

2.1 Brainstorming Technique

First, a brainstorming technique was used to generate a multitude of ideas. No limitations

were put on the ideas as people shouted them out. Therefore, there was no set criteria for this

first step in the concept development process. All the ideas were then written on a large sheet of

paper. Once the group had generated over sixty ideas, the list was examined and similar ideas

consolidated.

2.1.1 Short List Generation

Then the group voted using Pareto’s rule to generate a short list of the best ideas. Each

member of the team was allowed to place seven votes. Multiple votes for one item by the same

individual were permitted. The criteria each team member was asked to consider while they

were voting were the following: Criteria:

1. Ideas that sounded interesting and fun.

2. Products that would meet the requirements and limitations of the cell. For this

criteria, one had to consider the manufacturability and assembly of the proposed

product. For example, would it be feasible to manufacture and assemble the

product in the cell while using both robots and the CNC mill?

3. Would the product be capable of being manufactured in the small size that the cell

would require?

4. Would this product look impressive in its manufacturing and assembly to a tour

group of prospective students?



After each group member had voted, the votes were counted. The short list of ideas and

the number of votes for each item are as follows:

Product Number of Votes

1. Desktop Pen holder 8

2. Mini-hockey stick 4

3. Money Clip 4

4. Water Gun Assembly 3

5. Belt Buckle 3

6. Name Plate 3

7. Paperweight 3

8. Coaster 3

9. Toy 2

10. Fridge Magnet 2

11. CD Holder 2

12. Business Card Holder 2

13. Candle Holder 2

14. Platter 1

15. Clock 1

16. Cell Phone Stand 1

17. Screw Driver 1

18. Tape Dispenser 1

19. Tool Holder 1

20. Automated Bartender 1

21. Key Chain 1



2.2 Group Drawing Method

The Group Drawing Method was used to build on the team’s top three concepts: a money

clip, a mini-hockey stick key chain, and an engraved desktop pen holder. The team broke into

three groups and each group took a concept. Each group consisted of at least two of the three

majors. This allowed the designs to be more detailed since each major looked at the design from

their engineering discipline perspective. While doing this method, each group took into account

the constraints and requirements of the cell. It was necessary that each group consider the

following criteria in their design:

Criteria:

1. What material would the product be made of?

2. What components of the product would be manufactured in the cell and which

would have to be done offline?

3. How would each of the robots and the CNC mill be utilized in the manufacturing

and assembly of this product?

4. Approximately what size would the product be (do not need dimensions at this

stage, but discuss size using hands to illustrate)?

5. Determine the Bill of Materials.

During these drawing sessions, each team member informally evaluated the products

based on the defined criteria. It was then determined that the money clip should be eliminated

because it would not incorporate all the machines in the cell.

2.3 Empathy Method

The group chose not to use the Empathy Method in the Concept Development because

the focus of this project is on the manufacturing and assembly process rather than on the product.



2.4 Product Selection

Since the money clip was eliminated due to design issues, two possible product ideas

remained: the engraved desktop pen holder and the mini-hockey stick that would become a key

chain. In order to make the final decision, the team discussed each of the products and the

manufacturing and assembly methods that would be used for each. Some negative aspects of the

mini-hockey stick were its shape and size. Although the entire product would not be miniscule,

the blade was rather small. It was on the blade that the engraving would be. The product was

still capable of being manufactured, but with some difficulty. Since it appeared that both

products would be feasible, a vote was taken that resulted in a unanimous decision to produce the

engraved desktop pen holder.



3 Feasibility Assessment

Often times a feasibility assessment is performed on the top several concepts that a

design team generates. The feasibility assessment consists of a variety of questions that cover

areas such as technical, economic, market, and schedule. These concepts are scored based on a

predetermined scoring chart. The concepts are assessed in relation to a defined baseline concept.

The focus of this project is on an entire process. However, the group did have the opportunity to

design the product that would be manufactured and assembled in the cell. Through the concept

development method and examining the potential products based on the previously defined

objectives, the group chose to produce an engraved desktop pen holder as explained previously.

Since the product was already selected, we decided to perform the feasibility assessment

on two potential components for the product. Two different types of pen holders we found: an

adhesive base assembly and a set screw base assembly. Each came with the same swivel funnel

mechanism and matching pen. Both designs were examined and the assembly methods for each

were considered. The feasibility assessment was performed on each comparing them to a

baseline concept. The baseline concept chosen was a fully manual assembly of the pen holder

component. The questions used for the assessment are presented below, as well as the scores for

each question. A radar chart provides an illustration of the score results for each component.

Left – Adhesive baseRight – Set Screw base

Figure 1: Pen Holders



3.1 Adhesive AssemblyTechnical Question 1

Does the team have the skills needed to implement all aspects of the technologies for thisconcept?

Score: 2Answer: Between the team members, we have basic competence in all technical areas required toimplement this concept. Individuals may have to push themselves a little bit, but the basictechnology is within grasp.

With some work by all of us, we are pretty confident that we can complete all of our objectiveson time without exceeding our budget. We will need to learn some basic programminglanguages and the use of some equipment to build certain components of the system. We are incontact with some valuable resources that can help us in these areas.

Technical Question 2

Are all elements of the technology (components, materials, etc.) required to implement thisconcept available to the project team?

Score: 2 Answer: While most of the components needed are readily available, one or more criticalcomponents will either have to be developed specifically for this concept, or are currently inlaboratory testing by an outside supplier.

The majority of the components and materials are readily available for us. We are planning todevelop and build some fixtures for parts presentation. We are confident that we will also beable to perform these tasks in time.

Economic Question 1

How much will it cost to bring this concept to the customer? Or Does our firm have thefinancial resources to bring this product to the market?

Score: 3Answer: We can absorb the cost for this concept out of allotted budget. This concept can becompleted with the originally planned finances.

We have created a budget for all materials and components needed to make this concept areality. From our initial estimates it appears that we will be able to complete the project withoutrequiring any additional funding.

Economic Question 2



Does this product appear to have viability in the future economy?

Score: 2Answer: This concept assumes nor requires no fundamental shift in the economy. What happensin the national or global economy will have little or no impact on the success of this productconcept.

Our product does not rely on the economy. The process will be used for academic andeducational purposes. The product that our cell will create is no more than an example or trinket.

Market Question 1

What price will the market bear for a product based on this concept? Can we afford to makeand distribute the product at that price?

Score: NA

Again we will not be selling a product or even developing a production process to be usedoutside of this institute. Our work will be for non-profit and therefore the market will have noaffect on our decision to continue.

Market Question 2

How does this product fit with our current and future areas of strength?

Score: NA

As we are not doing work for an existing company there are no current products or processes tobenchmark against.

Schedule Question 1

How much time will it take to bring this concept to the customer? Or Does our firm have thetime to bring this product to the market?

Score: 3Answer: We can have this product concept done within our currently planned structure. Weprobably will not even have to ask for overtime!

This design and implementation for the process of building with the adhesive base should becompleted by the deadline. The cell should be completely functional at that time.

Schedule Question 2

How long is the window of opportunity in the market?



Score: 3Answer: This product will have a market available whenever it gets introduced. The need is notgoing away, and we see no other solutions on the horizon.

This process will be used for demonstrational purposes. Therefore whenever the process iscompleted there will a need for it. Also the product that we are creating is simple and relativelytimeless. We do not have to worry about a changing market.

Performance Question 1

How does this concept meet the top three needs of our immediate customer for this product?

Score: 3Answer: This product exceeds all of the customer expectations. Better than the baseline concept.

The adhesive pen holder exceeds all of the customer expectations for their top three needs. Asrequested it can be a trinket, uses the robots correctly, and uses the CNC appropriately. Toexceed the customer needs, the cell requires no manual workstation.


How does this concept meet the requests for “bells and whistles” that are not central to thecustomer’s demands?

Score: 2Answer: This product will make our customer a “raving fan” of the product. Same as thebaseline concept.

The adhesive pen holder will make our customer a “raving fan” of the product because isadequately meets the requests for “bells and whistles” that are not central to the customersdemand. It will demonstrate qualities such as complete use of cell, cleanliness of final product,and ability to be used as a trinket.




Is this concept capable of meeting all regulatory requirements?

Score: 3Answer: The proposed solution is an improvement over the current situation. Any difficultiesare overshadowed by other benefits. Better than the baseline concept.

The proposed solution of the adhesive pen holder is an improvement over the current situation.Any difficulties such as programming are overshadowed by the benefits of the final product.This meets all regulatory requirements as well as being better than the baseline concept.


Can this concept satisfy the needs of an additional user beyond those of our baseline customerthat it is being designed for?

Score: 3Answer: This product not only meets the needs of our current paying customer, but also couldform the basis for a whole new product line and customer base. Great launching point for a fullproduct line. Better than the baseline concept.

The adhesive pen holder not only meets the needs of our current paying customer, but also couldform the basis for a whole new product line and customer base. This concept satisfies the needsof an addition user because it is a great launching point for a full product line.



3.2 Set Screw AssemblyTechnical Question 1

Does the team have the skills needed to implement all aspects of the technologies for thisconcept?

Score: 0 Answer: No, and we have no idea where to get someone with this expertise, at any price. Itwould be difficult or impossible to complete one or more technical aspects of this concept asproposed.

We as a group feel that it will be near impossible for the robots we have to assemble the holdingfixtures with set screws. The robots would have trouble grasping the screws and getting thescrews into the threads. It would also be difficult for them to turn the screws numerous rotations.

Technical Question 2

Are all elements of the technology (components, materials, etc.) required to implement thisconcept available to the project team?

Score: 1 Answer: We can probably piece together materials and supplies to demonstrate the proof of thisconcept at a lab scale. We may have to invest significant resources towards solving one or twotechnical hurdles.

All of the materials for the design can be found and/or purchased. However, significantresources, time, and energy would be required to have the robot screw pieces together.

Economic Question 1

How much will it cost to bring this concept to the customer? Or Does our firm have thefinancial resources to bring this product to the market?

Score: 1Answer: Failing in this product would make the team look bad, but would not severely damagethe firm financially. The customer would feel like the concept was a waste of money if it fails.

The cost of bringing this design to a working cell should not cost that much money. However,the project would be a waste of money and time if this concept is attempted and the robot is stillnot capable of assembly.

Economic Question 2



Does this product appear to have viability in the future economy?

Score: 2Answer: This concept assumes nor requires no fundamental shift in the economy. What happensin the national or global economy will have little or no impact on the success of this productconcept.

Our product does not rely on the economy. The process will be used for academic andeducational purposes. The product that our cell will create is no more than an example or trinket.

Market Question 1

What price will the market bear for a product based on this concept? Can we afford to makeand distribute the product at that price?

Score: NA

Again we will not be selling a product or even developing a production process to be usedoutside of this institute. Our work will be for non-profit and therefore the market will have noaffect on our decision to continue.

Market Question 2

How does this product fit with our current and future areas of strength?

Score: NA

As we are not doing work for an existing company there are no current products or processes tobenchmark against.

Schedule Question 1

How much time will it take to bring this concept to the customer? Or Does our firm have thetime to bring this product to the market?

Score: 2Answer: We may overrun the schedule initially planned for the project, but discussions with thecustomer suggest that the benefits outweigh the increased time required.

If following this concept it may not be possible to complete by the deadline given. We believethat it will take longer to successfully program the robots to assemble with setscrews than thetime we are given.

Schedule Question 2

How long is the window of opportunity in the market?



Score: 3Answer: This product will have a market available whenever it gets introduced. The need is notgoing away, and we see no other solutions on the horizon.

This process will be used for demonstrational purposes. Therefore whenever the process iscompleted there will a need for it. Also the product that we are creating is simple and relativelytimeless.


How does this concept meet the top three needs of our immediate customer for this product?

Score: 3Answer: This product exceeds all of the customer expectations. Better than the baseline concept.

The setscrew pen holder exceeds all of the customer expectations for their top 3 needs. Asrequested it can be a trinket, uses the robots appropriately, and uses the CNC appropriately. Toexceed the customer needs, the cell requires no manual workstation and can be disassembled.


How does this concept meet the requests for “bells and whistles” that are not central to thecustomer’s demands?

Score: 2Answer: This product will make our customer a “raving fan” of the product. Same as thebaseline concept.

The setscrew pen holder will make our customer a “raving fan” of the product because isadequately meets the requests for “bells and whistles” that are not central to the customers’demand. It will demonstrate qualities such as complete use of cell, cleanliness of final product,and ability to be used as a trinket.


Is this concept capable of meeting all regulatory requirements?

Score: 3Answer: The proposed solution is an improvement over the current situation. Any difficulties areovershadowed by other benefits. Better than the baseline concept.



The proposed solution of the set screw pen holder is an improvement over the current situation.Any difficulties such as programming are overshadowed by the benefits of the final product.This meets all regulatory requirements as well as being better than the baseline concept.


Can this concept satisfy the needs of an additional user beyond those of our baseline customerthat it is being designed for?

Score: 3Answer: This product not only meets the needs of our current paying customer, but also couldform the basis for a whole new product line and customer base. Great launching point for a fullproduct line. Better than the baseline concept.

The set screw pen holder not only meets the needs of our current paying customer, but also couldform the basis for a whole new product line and customer base. This concept satisfies the needsof an addition user because it is a great launching point for a full product line.



3.3 Radar Chart


Feasibility Assessment of Pen Holders

0

1

2

3T1

T2

E1

E2

M1

M2

S1

S2

P1

P2

P3

P4Adhesive BaseSet Screw Base


4 Design Objectives and Performance Specifications

The purpose of this facet is to clearly define the project’s design objectives and

performance specifications. The design objectives are based on the customer’s requirements for

the project. Some of the design objectives were clearly stated by the customer where others were

determined by the team based on the project definition. The performance specifications refer to

any specs that are related to the functionality of the manufacturing cell as well as the product.

These are discussed in detail in the following sections.

4.1 Design Objectives

There are multiple objectives that are important for the team to meet during the project.

These objectives include using all equipment located in the cell and interfacing (integrating) all

parts of the manufacturing cell. The cell consists of two mechanical robot arms, a CNC mill, a

conveyor belt, and a manual station. More objectives include manufacturing a product with an

adequate number of steps, making a product that can be given away as a souvenir, and making a

product that can be recycled. The project team must also maximize throughput, optimize flow,

and minimize cycle time.

The first two objectives listed above are the main objectives for the project. These are

requirements that must be met in order for the project to be considered successful. The team has

decided to try and avoid using a manual station during the manufacturing process. There will be

some manual steps during set-up, but once the cell starts production there will be no human

interaction until the raw materials need replenishment. In order for this to be possible, it is

imperative that all the equipment is properly integrated. Each station will use sensors to allow

the cell to know where product and materials are at all times.

The next few objectives are related to the actual product that is to be manufactured and

assembled in the cell. These requirements were given to the team by the customers. Since they

would most likely be the individuals running the cell for demonstration purposes, the customers

wanted a product that they could possibly give away, disassemble and reuse if not given away.

By disassembling and reusing some of the product’s components, the quantity of material needed

for production would be reduced, thus reducing cost. The last few objectives are optimization

based requirements. The team decided that once it figured out how to make the cell function it

was important to engineer the system to be as efficient as possible.



4.2 Performance Specifications

The performance specifications of the cell focus mainly on the requirement to use the

equipment already in the existing cell. The manufacturing and assembly cell consists of a

friction-powered conveyor, an EMCO CNC mill, two Adept Robots, and an optional pallet stop

for a manual station. Additional specifications require anything that would assist the team in the

integrating of the machines in the cell. This includes but is not limited to sensors, air hoses,

pneumatic vises, robotic grippers, and part presentation fixtures. The team was given freedom in

determining the product to manufacture and assemble in the cell, the process flow, as well as the

grippers and fixtures that needed to be fabricated and built to successfully complete the project.



5 Analysis of Problems and Synthesis of the Design

This facet contains an in-depth analysis of the project from the industrial perspective, the

mechanical perspective, and the electrical perspective. This consists of examining the design as

well as the mathematical performance of the system. The synthesis includes the results from the

analysis and how changes can be incorporated. These are discussed in the following sections.

5.1 Industrial Analysis

One of the main components of the industrial analysis was determining the process flow

and allocation of tasks for each station. These process steps not only were influenced by the

product that was chosen, but also on the equipment constraints of the cell. These are discussed

in more detail.

5.1.1 Process Flow & Task Allocation

The manufacturing cell to assemble the pen holder is initiated by the user. After the

“start” function is begun, an aluminum block is loaded to the pick-and-place robot via the

aluminum block loader. The pick-and-place robot then loads the raw aluminum to the CNC

machine clamp in the correct orientation. The robot clears itself from the CNC machine and

machine cycle is initiated. The CNC cycle encompasses the carving of letters, border, and inset

squares for the pen holders. Once the cycle has been completed, the robot arm returns to the

CNC machine. The robot then clears the engraved aluminum block from the CNC machine

clamp and places it on the movable pallet. The pallet moves along the conveyor towards the

assembly robot. The pallet with the engraved piece on it stops at the assembly robot station. The

assembly robot then picks up one pen holder from the pen holder fixture and attaches them to the

appropriate locations on the aluminum block. The finished product is rotated along the conveyor

to the first station. The pick-and-place robot completes its cycle by placing the engraved desktop

pen holder into the finished goods bin. The flow diagram in Figure 2 helps to illustrate the

process.



Figure 2: Process Flow Diagram


User Initiates Cell Startup

Pick & Place Robot Places Part in CNC

A Part is Detected in the Part Feeder

A Part is Detected in the

CNC

The CNC Operation is

Complete

The Cell Cycle is Complete

The CNC Operation

Takes PlaceA Part is Detected in the Part Fixture

(Gate 1)

Pick & Place Robot Places Part

in Part Fixture

Assembly Robot Grabs and Attaches

Pen Holders

Pick & Place Robot Places Part in

Finished Goods Bin

A Part is Detected in the Part Fixture

(Gate 2)

Are there Pen Holders

Remaining?


5.1.2 Limitations of the Cell

There are many potential solutions when looking at the goal of the assembly cell. These

goals can only be reached and exceeded by taking into account the existing limitations. A large

portion of the flexibility of the cell lies in the funding of the project. While the budget of $1,500

allows for the goal to be attained, the $1,500 can also be seen as a constraint.

Primarily the budget does not allow the team to purchase any vital cell machines such as

robots or a newer CNC machine. The team must use the provided equipment. These semi-

primitive devices do not allow for much flexibility because programming and hardware fixtures

become difficult. The budget also limits the use of facilities planning to re-work the cell layout.

This is the case because to move devices like the CNC machine or the power source, the team

would need to purchase cables of substantial value.

Another limitation of the cell is dimensionality. On one hand, the part to be produced in

the cell cannot be more than one square foot by four inches height. The width and length are

limited because the conveyor pallets will not move something over the one square foot, and the

height is limited by the CNC mill. On the other hand, the cell is limited in every way by the

weight of the part to be assembled. Although the exact maximum weight the cell can handle is

unknown, the cell cannot handle anything of substantial weight.

Limitations are also device specific. The robots are unable to perform tasks that invert

the forearm past the elbow, perform operations like turning a screw, or rotate 360 degrees. The

CNC mill is only able to engrave simple patterns. The computers and programs have limitations

due to the age of their hardware and software. The languages to program cannot be changed so

the users must become skilled at the original programs. Also, the amount of code the machines

can store is limited.



5.1.3 Quality Function Deployment

This QFD or House of Quality as it is often called, was used to assess the two potential pen

holder components against a base concept. This was a visual tool to illustrate the

relationship between our customer requirements and the technical requirements.


OBJECTIVEQuality function deployment

(QFD) of Pen Holders

C

usto

mer

Rat

ing

(1 lo

w, 5

hig

h)

In th

e B

rinkm

an L

ab

With

in B

udge

t

Use

s al

l par

ts in

cel

l

Can

be

used

as

a te

achi

ng to

ol

Thou

roug

h tra

ckin

g of

gro

up a

ctiv

ityAbility to be used in Demos 5Base for future use 3Can be used as a "trinkite" 3No manual station 1An exhibit for tours 4Technical Marks Y $1,500 4 Y YBENCHMARK (-2, -1, 0, 1, 2)

ScoreOriginal Pen Holder 0 2 2 -2 1 -2 1Set Screw Pen Holder 0 2 1 2 1 2 8

Adhesive Pen Holder 2 2 1 2 1 2 10

-

++

+

Key to interrelationship:

- Strong interrelationship

- Medium interrelationship

- Weak interrelationship

Technical Requirements

CustomerRequirements


5.2 Mechanical Analysis

The mechanical analysis of the project focused mainly on the design of grippers for the

robots, various fixtures and part presentation devices, as well as an unclamping method for the

part in the CNC mill. The analyses and methods for each are described in the following

sections.

5.2.1 The CNC Vise

Figure 3: Pneumatic Vise

Currently, the existing vise in the cell at the CNC mill is a manual one. Therefore, in

concordance with the project’s objective to design a fully automated manufacturing cell, the vise

will either need to be replaced with one that can be controlled by a computer or somehow

eliminate the need to use the manual vise and use no vise at all.

The technical specifications of the cell are the following:

• 70 psi air pressure supply

• 10 lbf for clamping

• The vise must stay closed even if there is a failure in the air pressure

• Self-centering



Based on these technical specifications and the desired functionality, the team has considered

several possibilities: using a pneumatic vise, using a hydraulic vise, designing a vise similar to a

clamping device, or adapting a rotational system including a chuck on the actual vise, that would

do the tightening for the operator. The evaluation of both the advantages and disadvantages for

each solution are presented in Table 1.

Table 1: Vise Analysis

Advantages DisadvantagesPneumatic vise existing air pressure line

easy to implement good accuracy

The size, the weightThe price (~$1200)

Hydraulic vise Smaller than the pneumaticonePowerfulExcellent accuracy

The size the weightNeed to add a hydraulic powerunit The price (>$1000 W/o thepower unit)

Custom clamping device(using an air cylinder)

CheapAdjustable for otherapplications

Low powerLow accuracyLot of work for the team to buildit.

Rotational device Quite cheap Difficult to controllow accuracy

After careful consideration, the decision was made to design and build a clamping device

unique to the cell. The reasoning for this decision was based on the following criteria: both the

hydraulic and the pneumatic vise are almost what was needed in terms of capability, but

considering the size of the CNC milling machine it might be out of range and above all the

budget would not allow for the purchase of any of the options researched. The rotational device

could be a good solution since the current vise could still be used, but the position control would

be very difficult.

The custom clamping device is the most affordable solution. One of its main

disadvantages was the lack of power and accuracy depending on its design. However, since the

use of the milling machine will be limited to an engraving process there will not be huge cutting

efforts and the tolerances on the dimensions are fairly large. Based on the information gathered

and the obvious rewards of a custom clamping device, this concept was investigated further.



This custom pneumatic vise will be made of three major parts: an aluminum base, an

aluminum jaw plate, and a single acting (pulling) air cylinder with the spring extended. The base

part will be mounted on the CNC machine with the jaw plate and the air cylinder mounted onto

it, facing each other. (See the CAD drawing in the tech. data package for more detail).

The team plans to build the two aluminum parts, but will have to purchase the air

cylinder because it is a very specific type needed. There is the potential that this exact air

cylinder may be difficult to locate. If this is the case, a regular single acting (pulling) air cylinder

can be purchased, but a separate spring will have to be added. This is obviously not the preferred

option, but will still enable the team to reach the end goal of designing a pneumatic vise for the

CNC mill. The characteristics of the cylinder should be approximately ¼ inch, 1 inch, and 1

inch for the rod diameter with a male threaded end, the bore diameter, and the stroke

respectively.

5.2.2 Robotic Grippers

As mentioned before, one robot will be dedicated for the assembly and one for moving

the base part. Therefore, a different kind of gripper is needed for each robot. The design of the

cell is limited by the capability of the robots. These are four axis robots, three rotations and one

translation, but all on the same z-axis. An advantage is that air pressure can be supplied to the

grippers through the arm of the robot. Taking these constraints into consideration, the team

researched what robotic grippers were available in the market. The following solutions were

generated based on this research.



5.2.2.1 Aluminum Base Part Gripper Design


Figure 4: Aluminum Base Part Gripper


The robot located next to the CNC mill will have to grab the aluminum base part from the

feeder, place it in the pneumatic vise, and then release it once in the pneumatic vise. Once again,

an air-powered gripper has been chosen to compliment the configuration of the cell. Although

there are existing grippers in the manufacturing cell, they do not measure up to the defined

specifications. The problems with the current grippers are that the jaws’ maximum opening is

too small for the base part and the fasteners do not match the positions of the threads on the robot

arm.

Therefore, the team generated some solutions for adapting the grippers. For the jaws,

only a few eighths of an inch need to gained on the opening of the jaw so that the inside face of

each jaw can be milled. This will be by far the cheapest and the quickest method of modifying

the jaw opening. This approach will have to be verified through experimentation. If this method

fails, the team will have to build some new jaws. However, this would still be a feasible task

because it is not a huge undertaking. A small aluminum plate that will be mounted on the robot

will be built to accommodate for the fastening problems that currently exist. The gripper will

then be mounted onto the plate (See the CAD drawing in the technical data package). The team

researched grippers and found that there are three major kinds of pneumatic grippers on the

marketplace that are described in Table 2.

Table 2: Gripper Analysis

Cost Particularity Positioning Accuracy

Suction pad Low Need a flat surface on the top face ofthe part to grab it.

Low

Angular gripper Medium Can be easily modified to fit otherapplications by changing the fingers

Less clamping force than the parallelone because of the lever

Good

Parallel gripper Medium Best for a simple shaped part

Good clamping force

Excellent



The suction pad would not be a good solution because the engraving on the product’s base

would prevent the suction from effectively reaching the block. Furthermore, its accuracy might

not be enough for the positioning the vise requires. Although angular grippers and the

translational grippers would both match the project’s need, the parallel type seems better since

the aluminum base part is quite wide. Furthermore, there is an existing parallel gripper in the

Brinkman Lab. The dimensions of the existing parallel gripper are not perfect, but with simple

modifications it can be made to work for this application.

5.2.2.2 Pen Holder Gripper Design

Figure 5: Pen Holder Gripper Finger (Left), Pen Holder (Right)

One Adept Robot is required to assemble two pen holder swivel pieces to the aluminum

base. The pen holder swivels, shown above on the right, have an adhesive pad at the bottom to

adhere to the aluminum base. The team has decided to utilize a pneumatic angular gripper

already in the Brinkman Lab, but will need to design fingers for it.

A custom design finger, shown above on the left, was made for the angular gripper to

match the profile of the pen holder swivel. Two fingers are used to grab the swivel from the

sides. When the two fingers come together to pick up a single swivel the profile at the swivel

joint is picked up. The swivel joint causes design difficulties in that the pen holder swivel moves

around on a ball and socket joint. With this happening, the base of the swivel and the top part

will never be in the same position in two different pen holder swivels. This is why the fingers

were designed to grab at the swivel joint, so both the base and the top are grabbed causing them

to line up when clamped by the fingers. A rubber lining on the gripper fingers, not shown in the

drawing will be used to grab the profile of the swivel better.



5.2.3 Fixture Design

Various fixtures needed to be designed in order for our completed project to work as

efficiently as possible with very little human intervention. These fixtures will serve a variety of

purposes including parts presentation, a holding device for transport, and a location for finished

goods inventory to be stored.

Each fixture needs to be designed for compatibility with the machinery in the cell. The

robots have certain limitations in movement. Therefore, the fixture designs must take that into

consideration. The designs also try to keep the complexity down to a minimum because of the

limited budget, timeframe, and resources for the project. Gravity will be a large factor in the

fixture designs. As far as material considerations, the team will be selecting materials based on

cost, availability, and ease of machining.

5.2.3.1 Aluminum Base Feeder

Figure 6: Aluminum Base Feeder

The first process involved in the cell is the CNC-robot needs to pick up a blank aluminum

block (5”x3x”0.5”) to be put in the CNC machine. A gravity feeder, shown above, was designed

for the purpose of having the robot come back to the same position each time it needs a blank

block in the process. The design is based upon commercially available skate wheel gravity

conveyors available in the market. The cost of a conveyor with the specifications needed for our

project would run over $300. The group decided on building a simple design shown above,

which uses 608 bearings along 5/16” coarse threaded rods to provide a reduction in friction, so

the blank aluminum block can slide down the 30-degree slope easily. When a block is picked up



at the bottom by the robot, the next block will take its position. The support bars are all made

from 2”x4” wood, allowing for easy construction. The threaded rods and the bearings are

secured with 5/16” nuts. The feeder allows for approximately 10 aluminum blanks to be stored

at one time.

5.2.3.2 Pen Holder Swivel Feeder

Figure 7: Pen Holder Swivel Feeder

The pen holder swivel pieces are light in weight and tough to handle by a robot because

of the ball joint. Instead of using a gravity or spring feeder, a board with a pattern for 16

swivels, shown above, was designed. The magazine type feeders would not work in this case

because of the unusual profile and lightweight of the swivel pieces.

The board is designed with enough room for the robotic grippers to move to each piece

without touching the next piece. Another factor that is considered is that the swivels need to

have the adhesive pad on the bottom ready when placed on the board.



5.2.3.3 Pallet Cradle

Figure 8: Pallet Cradle

There are four pallets that travel around the cell on the conveyor belt. A pallet cradle,

shown above, was designed to hold one aluminum base at a time. This design has a plywood

piece for the bottom with two pieces attached to the plywood base to hold two corners of the

5”x3” piece of aluminum. The two corner pieces allow plenty of freedom for the robotic gripper

to pick-up or put down the aluminum base. The plywood base is attached to the conveyor

squares with four nuts and bolts since four holes are already provided in the conveyor squares.



5.3 Electrical Analysis

The challenge of the electrical system that needed to be designed for this manufacturing

cell was to provide a system that could interface with each of the four primary components of the

cell, provide flexibility as modifications are made, and monitor the activity that is taking place at

each location and provide feedback. It was decided that a central control system was needed to

control the communication between each of the sub-systems and to provide feedback.

A couple options were considered before deciding on how the cell was going to be

controlled. The first idea was to create a central computer that would monitor the operation of

the whole cell using the software package Labview. Labview provides an excellent system to

monitor the operations within a manufacturing cell and can be used to control the interfacing of

the different systems. However, after evaluating what hardware already existed in the cell,

Labview appeared to give only one added benefit. It would allow the operation of the cell to be

graphically displayed and data for analysis to be collected. The team concluded that this benefit

would not out weigh the added complexity of interfacing another system within the cell. The

second option was to use the existing hardware in the cell and setup a means of connecting all

the systems using Programmable Logic Controller (PLC) and Robot controller communication

ports.

It was determined that all of the electrical interfacing could be established running on a

24VDC system. The conveyer belt that is used to transport parts around the cell was setup to be

controlled by a PLC. The Omron SYSMAC CQM1 PLC in the cell is a 24VDC controller that

provides 32 inputs and 16 outputs that run on a 24VDC system. PLC'sare designed to interface

with numerous pieces of hardware and provide the needed power to each, making this a logical

choice to be the central electrical control system for the cell. The PLC directly controls the

pneumatic solenoids that will be used to control the flow of air to the robot grippers and

pneumatic vise that will be mounted on the CNC milling machine. Also the sensors and gates

that are used to control the movement of the conveyor pallet in the cell are directly controlled by

the PLC. The PLC will also interface with the robots in the cell through the digital I/O ports.



The signal assignments and controller pin-out can be seen in Figure 9 below.



PinSignal

Gate 1A Pos0

0.00

Gate 1B Pos1

0.01

Gate 2A Pos2

0.02

Gate 2B Pos3

0.03

Gate 3A Pos4

0.04

Gate 3B Pos5

0.05

Lift 1 Pos6

0.06

Lift 1 Down7

0.07

Lift 2 Pos8

0.08

Lift 2 Down9

0.09

Lift 3 Pos10

0.10

Lift 3 Down11

0.11

Lift 1 Dwn Permissive12

0.12

Lift 2 Dwn Permissive13

0.13

Lift 3 Dwn Permissive

PinSignal

Lift 2 Dwn CMD0

1.00

Lift 3 Dwn CMD1

1.01

Vice Open2

1.02

Move pallet to Assm.3

1.03

P'NP Gripper open4

1.04

P'NP Gripper close5

1.05

Assm. Finished6

1.06

Assm. Gripper Open7

1.07

Assm. Gripper Close8

1.08

91.09

101.10

111.11

121.12

131.13


140.14

Lift 1 Dwn CMD15

0.15

16GND

17GND

24V Input Slot 1

141.14

151.15

16GND

17GND

24V Input Slot 2


Pin SignalGate 1A Down 0 100.00Gate 1B Down 1 100.01Gate 2A Down 2 100.02Gate 2B Down 3 100.03Gate 3A Down 4 100.04Gate 3B Down 5 100.05

Lift 1 Up 6 100.06Lift 2 Up 7 100.07Lift 3 Up 8 100.08

Pallet in Load Pos. 9 100.09Pallet in Assm. Pos. 10 100.10

P'NP Gripper Air 11 100.11Assm. Gripper Air 12 100.12

13 100.1314 100.1415 100.1516GND17GND

24V Output Slot 3

Figure 9: PLC Signal and Pin Assignments



5.3.1 Robots

Each Adept robot is designed to interface and communicate with other external devices

through a 50-pin D-Sub port. Providing access to 12 inputs and 8 outputs that can be

individually addressed through the robot software that uses the control language V+. The input

circuit specifications provide for an operational voltage range of 0-24 VDC. Input signals will

register as “off” state for 0-3 VDC and “on” state for 10-24 VDC making it possible to interface

directly with the PLC. Since the robotic controller has the capability to control multiple I/Os, it

was decided that each robot would control the operations of the individual devices in their sub

cells. This was done for two reasons. First, the PLC has a limited number of I/Os available that

need to be reserved for controlling the overall flow and operation of the cell. Secondly, it adds

another level of complexity to the system when the team is developing and debugging the

software and hardware in the cell. With this setup, the operations in each sub cell can be

developed with very little interaction with the PLC needed, thus reducing the number of

variables to go wrong.

The digital I/O port connected to the pick-and-place robot mounted next to the CNC

milling machine will receive inputs from the PLC for when to start a new cycle and the robot

will signal the PLC when it has completed the cycle. Three proximity sensors will be wired

directly to this robot to monitor the base blanks in the part feeder, if a part is loaded in the CNC

vise, and the position of the milling head. The start of the Milling machine machining operation

will also be controlled by an output from this robot. For details on the signal assignments on the

pick-and-place robot refer to Figure 10.



Pin Signal Signal PinBlank Feeder Prox. 1Input 10011001 return 2Blank Feeder return

Vise Open Prox. 3Input 10021002 return 4Vise Open returnCNC Pos. Prox. 5Input 10031003 return 6CNC Pos. return

Pallet Pos. 7Input 10041004 return 8Pallet Pos. return9Input 10051005 return 10

11Input 10061006 return 1213Input 10071007 return 1415Input 10081008 return 1617Input 10091009 return 1819Input 10101010 return 2021Input 10111011 return 2223Input 10121012 return 24

Vise Open 25Out 0001+Out 0001- 26Vise Open returnCNC On 27Out 0002+Out 0002- 28CNC return

Pallet Move 29Out 0003+Out 0003- 30Pallet returnGripper Open 31Out 0004+Out 0004- 32Gripper Close 33Out 0005+Out 0005- 34

35Out 0006+Out 0006- 3637Out 0007+Out 0007- 3839Out 0008+Out 0008- 40

Bypass 41E-Stop E-Stop 42Bypass43E-Stop E-Stop 44 45 4647 4849 50

Figure 10: Digital I/O Pin-out for Pick-and-place Robot



The digital I/O port connected to the assembly robot will also have inputs wired to the

PLC to signal cycle start and end. Two outputs will signal the PLC to open and close the robot

grippers. Two input signals will be connected to this port, the PLC will signal when a machined

base has arrived at the assembly station, and a proximity sensor will monitor the pen funnels in

the dispenser. For details on the signal assignments on the assembly robot refer to Figure 11.

Pin Signal Signal PinPallet/w blank pos. 1Input 10011001 return 2Pallet/w blank return

Funnels in mag. 3Input 10021002 return 4Funnel return5Input 10031003 return 67Input 10041004 return 89Input 10051005 return 10

11Input 10061006 return 1213Input 10071007 return 1415Input 10081008 return 1617Input 10091009 return 1819Input 10101010 return 2021Input 10111011 return 2223Input 10121012 return 24

Assembly finished 25Out 0001+Out 0001- 26Assembly returnGripper Open 27Out 0002+Out 0002- 28Gripper Open ReturnGripper Close 29Out 0003+Out 0003- 30Gripper Close Return

31Out 0004+Out 0004- 3233Out 0005+Out 0005- 3435Out 0006+Out 0006- 3637Out 0007+Out 0007- 3839Out 0008+Out 0008- 40

Bypass 41E-Stop E-Stop 42Bypass 43E-Stop E-Stop 44

45 4647 4849 50

Figure 11: Digital I/O Pin-out for Assembly Robot



5.3.2 Milling Machine

The Emco Milling machine was not designed to support digital I/O interfacing with

external devices. To bypass this limitation, a work around has been developed. The program

that will be written to engrave the pen holder base will start and end with the milling head

position in a part load and unload position that is clear of the robot motion. It has been

determined that a milling machine program can be started by the pressing of a single button on

the control panel and a relay will be wired into the panel so that this switch can be controlled by

an output from the robot. A proximity sensor will be mounted on the milling head to signal the

robot that the machining operation has ended and the part can be unloaded.

5.3.3 System Feedback

A major challenge of automated systems is to provide feedback to the control system

when there is a malfunction. To this end, proximity sensors will be mounted in each location

that parts are being fed into the cell, and to monitor the movement of a part within the cell. Also,

sensors will be placed on each of the mechanical systems such as the vise jaw and the milling

head to verify that they are in the correct position before an operation takes place. Proximity

sensors that detect a ferrous metal passing in front of the sensor will be used in most locations.

The sensors used in the cell will be based on a 3-wire control, making it possible for the sensor to

be wired normally open or closed depending on the application.

5.3.4 Software

The machines in the manufacturing cell will be programmed using the control software

that has been developed by the manufacturer of each machine. The controller for the Adept

robots uses the language V+ to control the movement of the robotic arm along three axis of

motion. Programs can be written for the robot that controls the movement of the arm to specified

locations and it can support conditional logic. Within the program the status of the digital I/Os

can be monitored and outputs can be turned on and off. Making it fairly simple for the robots to

communicate with external devices.

The Emco CNC milling machine has three axis of motion and is programmed using

Numerical Control code. Unfortunately the NC code used for this machine is non-standard and

has limitations such as when defining an arc, the angle must be less than or equal to 90 degrees.

This prevents the use of standard Computer Aided Manufacturing (CAM) packages from being



used to generate the NC code. In addition to this, the controller can store up to only 300 lines of

code, severally limiting the complexity of the machining that can be performed on this machine.

This is why the machining that will be done on this machine within the cell will be limited to a

basic engraving. The idea of buying an after market PC controller for the milling machine was

considered and the team looked into the cost of converting the existing controller. It was

determined that this would be fairly expensive and it would really be outside the scope of the

current project.

The software that will be used to program the PLC controller is SYSWIN 34. The

software will be installed on a computer and the controller logic is programmed on a standard

ladder diagram designed for PLCs. The program then can be downloaded to the PLC via an RS-

232 connection. The software also allows the user to monitor the operation of the PLC when a

program is being executed to verify that everything is working properly.

The program code that is going to be developed to run this cell is going to be broken into

several modules. Each module will only execute after an input condition assuring each system is

in the correct position and orientation has been met. This will reduce the chances of

malfunctions propagating through the whole manufacturing cell. For a detailed explanation of

the program flow refer to the flow chart included in the appendix.



6 DFX Analysis

Design for ‘X’, or DFX as it is referred to, is a very important aspect of the design phase

because it takes into consideration many factors such as usability, environment, remanufacturing,

assembly, disassembly, reliability, safety, cost, manufacturability, aesthetics, and material

handling. In some cases, the product being designed may not need to be examined from all the

DFX perspectives, however, several usually apply. This project required many designs including

the design of robotic grippers, a pneumatic vise, multiple part presentation fixtures, as well as the

product to be manufactured and assembled in the cell. An informal DFX Analysis was

performed for each item that was designed. The following sections define what was considered

for each ‘X’ and how DFX is incorporated into the items’ designs.

6.1 DFX Definitions

In order to fully understand each ‘X’ of DFX, it must be clarified what each one takes

into consideration and how it is an improvement to the product and the process. The following

sections define what the group considered under each DFX category when performing a DFX

analysis on the designs.

6.1.1 Design for Usability

Design for usability encompasses the concept of poka-yoke, which is the method of

mistake proofing designs. Taking into consideration during the design phase any possible errors

that could occur when operating the product can help the designer revise the design so that these

errors do not occur. Most times, these errors are considered human errors but it is generally not

the operator’s fault, but rather the designer’s fault. The placement or visual design of a device or

control may affect how the operator views its function. For instance, if two controls look very

similar but perform drastically different functions, it is quite possible that the operator could

mistake one for the other, resulting in dire consequences. In order to safeguard against errors

that may be attributed to forgetfulness, misunderstanding, identification, inexperience, and

inattentiveness, the designer should error proof the design. Some possible means of error

proofing would be to alert the operator in advance, provide training, standardize operations and

controls, provide skill building, and provide work instructions. These techniques may help to

reduce or even eliminate what is termed human errors.



6.1.2 Design for Assembly

Design for assembly involves the ease of which something can be assembled, either by a

robot or a human. Of course, depending on which is performing the assembly and the level of

sophistication of the robot, different assembly methods must be considered. According to

Boothroyd and Dewhurst, there should be a minimum number of parts that each mechanical

device can function with. In order to determine this minimum number, several characteristics

must be taken into consideration. For example, the designer can determine if snap fits can be

used instead of fasteners. Also, to reduce the difficulty in assembling a product, one should

consider the orientation of the product as well as the orientation of the part(s) as they are

assembled onto the product. The assembly time will be reduced if the part is inserted from the

top, the part is self-aligning, the part does not need to be aligned, it is a one hand assembly, no

tools are required, it can be assembled in a single linear motion, or the part is secured by

insertion. Again, a human and a robot will have different eases of assembly. A motion that is

simple for a human may be too complex for a robot or visa versa. Also, the complexitity of the

robot and its constraints need to be considered as all robots do not have the same capabilities.

6.1.3 Design for Remanufacturing and Design for the Environment

Design for remanufacturing and design for the environment are concepts that go hand in

hand. The effects that a product will have on the environment throughout its lifetime as well as

after the product’s life is over, must be taken into consideration. It is beneficial to consider how

the product will be disposed of once its life cycle is over. By considering this, it can also be

determined if parts can be designed for remanufacture or reusability. A prime example of design

for remanufacture is the Kodak one time use camera. The camera itself is recycled so that it can

be used many times before the quality begins to deteriorate. Even then, the plastic can be melted

down and reused. Not only is this design method beneficial to the environment, but it is cost

effective for Kodak. They are able to essentially sell the same camera over and over, thus

increasing their return on investment. Therefore, it is important to consider several

environmentally conscious design practices when designing a product. These consist of

designing for waste elimination, material conservation, energy conservation, disassembly, and

recovery and reuse. Some ways in which to design for waste elimination would be through

resource reduction, separability, avoiding material contaminants and designing for waste

incineration. By designing for material conservation, one can design multifunctional products,



specify recycled or renewable materials, use remanufactured components, design for longevity,

design for packaging recovery, and design reusable containers.

6.1.4 Design for Manufacturing

Design for manufacturability is concerned with the methods, materials, and equipment

involved with the manufacture of a product. In some cases, the equipment that shall be used in

the manufacture of a product already exists so the process must be designed around the

capabilities and limitations of the equipment. The materials that are used in conjunction with the

equipment must also be compatible. The manufacturability will vary depending on the product

or process that is being designed.

6.1.5 Design for Disassembly

Design for disassembly involves determining how the product can be taken apart for

service and maintainability as well as at the end of the product’s life cycle. Some ways in which

design for disassembly can be incorporated are by designing for easy removal of the

components, avoiding embedded parts, and optimizing the disassembly sequence. It is also

important to simplify the component interfaces by avoiding springs, pulleys, harnesses,

adhesives, welds, and threaded fasteners. Designing the product for simplicity can also speed up

the disassembly process. In order to design for simplicity, one must reduce the number of parts

that the product is comprised of, design multifunctional parts, and use common parts so that the

product can be serviced easier and its life cycle extended.

6.1.6 Design for Reliability



Design for reliability is an important consideration. In order for a process to function

effectively, it must be reliable. Otherwise, too many errors and disruptions would occur. These

could affect production time as well as quality. The reliability of each machine or process varies

as to the exact specifications. In some cases it is required that a part be presented in the exact

same location each time for a robot to pick it up. Most times, the orientation of the part needs to

be the same for a robot so that it is placed in a machine correctly. This is true for human

operators in that having a part presented to them in the same and proper orientation each time

would reduce the number of motions and as a result reduce the cycle time. The more reliable a

device or process is, the more efficient a process will be and the better the quality.

6.1.7 Design for Safety

Design for safety is something that should be considered when designing anything. Any

extra effort that can be taken to ensure that a device is safe for those operating it or around it

should be taken. Some examples of safety measures that can be taken are placing guards around

machines, using two handed activation switches for operator initiated machines, providing

emergency shutoff buttons within easy access of the operator, and any methods associated with

individual devices that will prevent injury.

6.1.8 Design for Cost

Design for cost is also important in most situations because a project is usually operating

on a predetermined budget. Therefore, it is important to make every aspect of the design and

production phases as cost efficient and effective as possible. Design for cost should be

considered in even the earliest stages of the design process so that the product or process is

designed to be cost efficient. Often times, designers do not consider cost in the design phase as

much as they should and then when they reach the production stage, find that the final design

will be quite costly to manufacture and build.

6.1.9 Design for Material Handling

Designing for material handling can reduce the amount of time the assembly line or cell

is disrupted for replenishing material or even the handling of the material during the assembly

process. Some attributes that can affect the handling, feeding and storage of materials and



should be considered when designing any type of part presentation devices are symmetry,

thickness, nesting, fragility, slipperiness, sharpness, stickiness, use of mechanical assistance,

weight, size, tangling, flexibility, and if it requires a two hand operation. It is also important to

make the design and process contamination resistant if that is a requirement of the product.

When feeding devices are being designed, it is beneficial to take advantage of properties such as

gravity that do not require any mechanical assistance. This reduces costs as well as the chance of

mechanical failure. The proper orientation of the part must be considered as well so that it is in

the appropriate presentation for the operator or robot.

6.1.10 Design for Aesthetics

Design for aesthetics is a concept that increases customer satisfaction of a product or

process as well as the perceived quality. If a product provides a wonderful function but is not

visually appealing to a consumer, it will not be successful in the market. It seems like a vain

aspect to consider, but can actually influence a consumer’s perceived quality of the product. It is

also important to design the process so that it is aesthetically pleasing so that if tours of it are

provided, people will be impressed. This does not mean that the process needs to look like a

piece of artwork, but simply that it is visually appealing.

6.2 Product Design

It was important that the design of the product to manufactured and assembled in the cell

take several of the DFX aspects into account in order to meet the customer’s objectives. The

analysis included design for manufacturability, assembly, disassembly, usability, and aesthetics.

The reasons why these aspects needed to be considered are explained in the following sections.

6.2.1 Design for Manufacturability

The product was designed for manufacturability by taking into account the various tools

and machines available in the manufacturing cell. The product had to be designed so that it

could be machined and assembled in the cell with the given equipment. The product had to be of

a small enough size to fit on the given pallets, which then are transported to each machine via a

conveyor belt. The base is made out of aluminum, which is a metal that is fairly easy to machine

using the CNC mill. The pen holder funnels can be gripped and placed on the base using the

robotic arms and grippers.



6.2.2 Design for Assembly

The product was designed for assembly by its simplicity. It was designed to be as simple

as possible, yet complex enough to involve all equipment in the cell. The product only consists

of two pieces, an aluminum base and one pen holder funnel. The funnel has an adhesive base

which makes it much easier for the robot arm and gripper to attach it to the aluminum base. This

is in contrast to a set screw or other form of attachment which is much more difficult for a robot

arm to perform.

6.2.3 Design for Disassembly

An important facet in the world today is creating products that minimize their impact on

the environment. Many designers, including the members of the Automated Cell team, are

recognizing this element and are taking into consideration the process, tools, and people involved

in introducing a product into the market. The team therefore has made it a personal goal, as well

as a requirement, to produce a cell and a product that are user and environmentally friendly.

One technique that can be used to accomplish this goal is Design for Disassembly. In

particular the cell itself is involved with design for disassembly. A primary situation is the ease

of disassembly of the track the conveyor flows on. Another example is the ability to test the cell

without physical waste. These “dry-runs” are important to make it clear the condition of the cell

as well as to see if any changes need to occur. Another way the cell classifies itself into the

design for disassembly category is that it is being created with the idea of future, or different

uses. This idea of re-assembly after disassembly will help the team’s customers for years to

come. This will reduce or eliminate the need to replace the existing equipment.

Another aspect that the team worked into design for disassembly is the part that is being

manufactured. One problem that arose with the selection of the adhesive pen holder was how to

disassemble that particular pen holder without the entire product going to waste. Several ideas

are in process, including pealing one half of the adhesive for a few test pieces, using a secondary

adhesive that is made for stick and unstuck tasks, and running the test runs without the adhesive

exposed. The pen can be disassembled for cleaning, or refilling because it is composed of screw

connections.




Another technique that lends itself to user and environmental friendliness is Design for

Usability. Usability has influenced the design of the cell. The team believes strongly in the user

controlling the machines and events in the cell, not the machines controlling the user. To do this

there needed to be a step towards interface simplification. To start out, lines of code will literally

do everything in the cell. This limits the ability for maximum control of the cell, and little to no

monitoring ability. To help alleviate this problem, the team will use simulation software to make

debugging easier. The product of the pen holder was also scrutinized for usability. The team

determined if the customers would find the product and process easy to use.

6.2.5 Design for Aesthetics

The product was designed for aesthetics by using a base and pen holder funnels that are

similar in color. The aluminum base will be polished and black anodized, and the funnels have a

shiny silver appearance. The pen holder was designed to look professional, but also to serve the

function of holding a usable pen. The base is engraved with the R.I.T. logo using the CNC mill

to add further to its professional appearance. One of the benefits of the black anodizing of the

base is that when the product is engraved, the silver will show through and stand out. The edges

of the aluminum base are smooth and chamfered to avoid injury to the user as well as provide a

subtle and tasteful border to the product.

6.3 CNC Vise Design

The pneumatic vise for the CNC mill also considered several DFX factors, however the

factors important to this design focused on the functionality of the vise. Therefore, the aspects

considered were design for safety, usability, reliability, and adaptability. Each of these aspects is

described in detail in the following sections.

6.3.1 Design for Safety

Safety is an important factor to consider in the design of any device, but especially important

when pneumatics are involved. The main issue that may occur while using this vise, and that is

potentially dangerous, is the concern that the aluminum piece could fly out if the vise happens to

release its clamping while the piece is being milled. The cause of this would be if the vise is a

basic air powered device and the air pressure happens to fail.



To avoid this hazard, a strong spring has been added onto the air cylinder, which by itself can

bring enough force to keep the piece tightened. Then the cylinder will be used to release the

clamping. As a safety precaution, the normal position of the vise is closed, spring loaded.


Because the cell is fully automated, there are no operators controlling the vise.

Therefore, the pneumatic vise needed to be designed for the CNC machine to use without error.

With that in mind, the main issue to override was the rough positioning caused by the poor

repeatability of the robot arm added to the uncertainty of the gripper when it releases the piece.

Then the vise has to clamp the piece in the same position wherever it is released by the gripper.

Hence the vise has been designed with a special shape to the jaw plate which automatically

allows the piece to self-center itself while it is being clamped.

An alternate solution would have been to provide clamping on two sides of the part.

However, the engraving process for this product does not require such precision and the

increased cost of such a solution would not be justified.

Lastly, the vise can be easily removed from the CNC and easily remounted on it with out

any kind of adjustments or settings to make since only the base part of the vise is mounted onto

the CNC and the bolts can be accessed without removing either the jaw plate or the cylinder.

6.3.3 Design for Reliability

Reliability of course has been taken into consideration since the device is designed to last the

cell life. Minimal wear should occur on the cell because the cell will not be running all day,

everyday. It has been taken into consideration that the vise will not have to do a lot of opening

and closing since the cell will only be used as a teaching tool and not in intense production line.

However the device still needs to work without failing. In this case, failure would be

everything that would lead to modify the positioning of the piece during the machining.

Therefore, all the fasteners must be secure and the clamping capability should be increased

toward the theoretical force required by the process. In this way, every critical part of the vise

has been slightly oversized. Unfortunately, the overall cost is ridiculous.

6.3.4 Design for Adaptability



This device has a long potential life and represents an important cost in the project. In order

to design the cell to be flexible so that in the future it can manufacture and assemble a different

product, this vise must be adaptable to fit a product that may require a different milling process,

or just be a different size.

Therefore the vise was designed so that only by changing the jaw plate it will fit a different

size part, and only by changing the spring it will fit another milling operation, if this one requires

more clamping force. Furthermore, the cylinder is double acting so that a clamping force with

air pressure can be added in addition to the spring.

6.4 Fixture Design

Three main fixtures had to be designed to aid in the manufacturing and assembly of the

product. Because the cell is fully automated, the team was faced with the task of designing

fixtures that were very reliable and also presented the part to the robots in a manner that they

would accept it. For instance, the pick-and-place robot had to receive the aluminum blank in the

same location every time. This put some limitations on the type of fixtures that could be

designed. A DFX analysis was performed and is discussed with respect to each fixture in the

following sections.

6.4.1 Aluminum Blank Part Feeder

The aluminum blank part feeder was designed to present the blank aluminum blocks to

the pick-and-place robot at the first station. The team was faced with some restrictions based on

the robot and available space. A detailed DFX analysis is provided in the following sections.

6.4.1.1 Design for Reliability



Design for reliability was a key component in the designing of the aluminum blank part

presentation device. Due to constraints of the existing robot in the cell, it was required that the

aluminum block be presented to the robot in the exact same orientation and location each time.

Therefore, it was necessary that the fixture be reliable in its accuracy of presentation to the robot.

This placed some constraints on the design team from the very beginning. Several different

methods of presenting one piece at a time in the correct and same location were considered.

Once reliability was considered for each and the ones that were deemed unreliable were

eliminated, the team was left with a couple choices such as using springs or gravity. The team

then had to consider the designs based on the other DFX aspects.

6.4.1.2 Design for Manufacture

The fixture to be used for the aluminum base of the pen holder needed to be designed

with manufacturability in mind. Due to a limited budget and time constraints imposed on the

group with the structure of the class, the team needed to develop a design that could be built both

quickly and cost effectively. Each blank aluminum part would have to be presented to the Pick-

and-Place robot in the exact location as the previous one in order for the robot to grab it. To

meet this requirement, the fixture design chosen utilizes gravity. Other designs including springs

and other mechanisms for parts presentation were considered, but based on simplicity, a gravity

driven feeder was chosen as the best alternative. When the robot takes a base component from

the fixture the other blanks stacked above it will fall into place along the rollers.

Another key decision for the manufacturability of the fixture revolved around the

structural components of the design. The material of choice for this particular fixture is wood.

Wood is much cheaper than any metal such as aluminum that may have been selected. Wood

also was chosen because the team would be able to assemble the fixture much easier than trying

to machine one. The team members can build the entire fixture themselves instead of having to

rely on outside help in the build process. Due to some natural variation in wood, the fixture

dimensions will not as precise as if it were built from another material, but for our purposes the

wooden design should be sufficiently accurate. Another bonus of the simplistic design is that all

of the materials required can be purchased off the shelf at any major hardware store. This simple

advantage of using only one local vendor has helped the team to build the fixture quite rapidly

without much delay. Since the vendor was local rather than an online supplier, any lead times

generally associated with ordering materials have been eliminated.



6.4.1.3 Design for Cost

Design for cost was also considered in the design phase of the aluminum base part

presentation device. The main area that cost would be a factor was in the materials that would be

chosen for the building of the fixture. Since it was not necessary that the fixture be constructed

out of metal, the team decided to build the fixture out of wood. The material cost of wood is

much cheaper than metal as well as the cost in terms of labor. Although the team would be able

to request outside help with the building of the fixture, it may not come freely or within the

desired timeframe. Therefore, to eliminate any hassle of enlisting outside assistance in the

building process, the team decided to build the fixture themselves, thus resulting in the choice of

wood over metal. Wood required many tools that the team is familiar with and has easy access

to whereas machining metal would take more instruction and availability of the necessary

equipment may be limited. Based on all these considerations, wood seemed to be the optimal

choice.

6.4.1.4 Design for Material Handling

Design for material handling was a not a major issue with the aluminum blank part

fixture because the aluminum blocks do not exhibit any attributes such as tangling or fragility.

The only considerations in terms of material handling that needed to be taken into account was

the orientation of the part and that the robot could easily remove the part from the fixture. For

this reason, a single part at the end of the fixture needed to be presented in a flat position for the

robot. This is illustrated in the AutoCAD drawing of the fixture located in the technical data

package.

6.4.2 Pen Holder Swivel Feeder

The purpose of the pen holder swivel feeder is to present the pen holder swivels to the

assembly robot in a manner that it will accept. The feeder designed is a magazine type feeder.

There were not a great deal of DFX aspects that needed to be considered, however, the few that

were appropriate are described in the following sections.




The pen holder swivel feeder was truly designed for cost. The design of the swivel

feeder machines the piece out of an inexpensive polyboard material which was already in the lab.

Therefore, no materials were actually purchased to fabricate the pen holder swivel feeder.

6.4.2.2 Design for Useability

The pen holder swivel feeder has been designed for usability for both the setup person

and the robot. The feeder is rectangular so that the robot can be programmed to go to specific

coordinates each time checking if there is a pen holder at that location until the entire board is

empty. When the feeder is empty, a setup person will refill the board with the pen holder swivels

and the robot will repeat its program.


In the design of the of the pen holder feeder, the assembly robot needs to pick up a swivel

pen holder and assemble the pieces in the same orientation from part to part and swivel to swivel.

The two parallel rows of square holes to fit the swivels provide reliability and consistent

orientation of the pen holder swivel bases. The setup person will need to make sure that the

funnel portion of the pen holder is somewhat vertical. If the funnel is slightly slanted, the fingers

on the gripper can adjust it.

6.4.3 Pallet Cradle

The main concern with the designing of the pallet cradle was to provide reliability so that

the robots would have no trouble accessing the part. As with any design, it is also important to

consider cost. Therefore, the two aspects of DFX that the pallet cradle design found important

were reliability and cost.


The challenge surrounding the pallet cradle was keeping the pallet cradles in the same

location from pallet to pallet to reduce error when assembling the swivel pen holder to the

engraved aluminum in the pallet cradle. Two holes on the top of the polyboard were used to

attach the cradle to the plywood. Once one piece of plywood had the correct two holes in it, that

piece could be used to align the next polyboard pieces to their respective plywood.




The design of the pallet cradle utilized an inexpensive polyboard material to machine the

piece out of, which was already in the lab and a small amount of plywood from a hardware store.

Therefore, the pallet cradle was very inexpensive to fabricate.

6.5 Gripper Design

It was important that the each gripper be designed for cost, safety, and reliability. At

times, these three DFX aspects can contradict one another, however, the team was quite

successful in achieving all three without having to jeopardize anything.

6.5.1 Aluminum Base Part Gripper

The aluminum base part gripper was not a large undertaking. The part that the gripper

was required to grasp was the aluminum base which is a rectangular part. The robot’s existing

gripper met the necessary specifications with minimal adjustments.


With the gripper, most of the cost was associated with the pneumatic gripper part and not

the machined fingers. Reusing a parallel gripper found in the lab greatly reduced the cost of this

gripper.

6.5.1.2 Design for Safety

In the instance of a pneumatic failure, the part would only drop vertically, since the

grippers grab from the top. Therefore, reducing the chance of injury to an operator.


In gripper design, reliability plays a major role. The aluminum base gripper needs to pick

up the base aluminum part without error. The gripper was designed to grab the sides of the

5”x3”x0.5” aluminum block on the 0.5” sides across the 3” span side. The gripper utilizes a very

simple design out of aluminum with rubber lining to insure a very secure grab of the aluminum

block.



6.5.2 Pen Holder Gripper

The majority of the complications of designing the pen holder gripper came in the

physical design of the fingers. Because the gripper would remain in the cell and be used every

time the cell was run, design for the environment was not an issue. Also, since the grippers

would be fabricated outside the cell, the focus of the design was on functionality and safety

rather than manufacturability and assembly. The DFX analysis is discussed in the following

sections.

6.5.2.1 Design for Safety

For safety purposes, in the instance of a pneumatic failure of the gripper, the swivel pen

holder would not drop because the design of the fingers grabs around the profile of the swivel.

Also, the swivels are too light to force the fingers to move.


With the gripper, the majority of the cost comes from the pneumatic gripper part and not

the machined fingers. Therefore, by reusing a parallel gripper found in the lab the overall cost of

the gripper was greatly reduced. Only a small amount of aluminum had to be purchased to

machine the fingers.


A major challenge of designing the pen holder gripper was to make sure each pen holder

is picked up in the same place and can be attached to the aluminum block . The swivel in the pen

holder provides a problem because the gripper can not grab just the top of the pen holder and

assemble the holder to the block. The pen holder would bend in the middle causing assembly

error. Therefore, to insure the pen holder is grabbed securely and in the same place every time,

the gripper grabs the whole profile of the pen holder, above and below the swivel. Below the

swivel, near the base of the pen holder, the profile of the gripper design grabs tighter. Under the

swivel, there isn'tenough surface on the swivel to provide a secure grip, so the profile of the

gripper extends above the swivel with a looser grip. In the case where the top of the swivel isn't

exactly aligned with the base of the swivel, the gripper will straighten the top to provide enough

gripping surface.

The gripper design also utilizes aluminum with a rubber lining in the profile. The rubber

lining is only where the gripper actually grabs the part. The material selection of aluminum



provides a fracture free gripper since the pen holders are very light in weight. The rubber lining

provides the gripper with a slip free grab of the pen holder.



7 Detailed Discussion of Cell

The design to be engraved was created to be simple yet tasteful and consists of block

letters of ‘RIT’ in italics and a small tiger paw in the lower left hand corner. The team made a

decision to have the aluminum bases black anodized so that when the CNC mill engraved the

base, the engraving would shine through in silver. The overall appearance of the pen holder was

improved with the black anodizing, however, it is entirely possible to manufacture and assemble

the engraved desktop pen holder without having the bases black anodized.

Figure 12: Finished Product – Engraved Desktop Pen Holder

7.1 First Station

The first station of the cell consists of the CNC mill and the Pick-and-Place robot. A

blank aluminum base is presented to the robot from the aluminum blank part feeder. The Pick-

and-Place robot removes the base from the feeder and places the part in the CNC mill. The part

is then engraved in the CNC mill. When the milling cycle is completed, the Pick-and-Place

robot removes the part from the pneumatic vise and places the part in the pallet cradle on the

conveyor. The part then travels to Station 2. Station 1 is also the final station in that when the

finished engraved desktop pen holder arrives back at Station 1, the Pick-and-Place robot is

responsible for removing the product from the pallet cradle and placing it in the Finished Goods

Bin. The following sections discuss the equipment and fixtures at Station 1 as well as any

changes that were made to the original design of each.



7.1.1 Pick-and-Place Robot

The pick-and-place robot grips blank aluminum bases from a nearby part feeder and

places them in the CNC mill’s pneumatic vise. Next, the robot sends a signal to the CNC mill to

start the engraving program. The pick-and-place robot then waits for the CNC to finish. If a

pallet arrives at the robot’s station, the robot will use a sensor located on it’s gripper to check for

a finished part located in the pallet cradle. If it detects a finished part then it will pick up the part

and place it in the finished goods bin. After the CNC is finished with the engraving process, the

robot will take the part from the vise and place it in the pallet cradle. The robot will then release

the pallet to the next station, which is the assembly station. The pick-and-place robot will

continue this process until it senses that there are no more blank bases in the part feeder. Then it

will unload the CNC, after it has finished engraving, for the final time and wait for the finished

part to arrive on the conveyor belt to its load/unload station. Then it will place the part in the

finished goods bin.

The pick-and-place robot has the ability to send and receive signals. The robot uses

output signals to: open and close the grippers, to open and close the pneumatic vise, to start the

CNC mill, and to release the pallet to the next station. The robot receives input signals from the

PLC to: tell it if any blank bases are in the feeder, to tell it when the CNC mill is in load/unload

position, to let it know when a pallet has arrived at its station, and to let it know if there is a

finished part in the pallet cradle.

The pick-and-place robot was originally located where the assembly robot is currently at.

It was moved to the opposite side because the conveyor belt only travels in one direction. It

made more sense to have the engraved part travel a short distance to the assembly station rather

than the long way around the conveyor. This allows for the finished goods to spend the most

time on the conveyor instead of the WIP (work in progress), which is better for throughput and

demonstration purposes. The pick-and-place robot was also placed on a steel mount to give the

robot arm and gripper clearance into the CNC mill.

There are a couple ways in which the pick-and-place robot could fail. The first would be

the grippers, which could fail by having an air pressure failure. They could also fail by not

properly gripping the aluminum base. This could occur if the base feeder, CNC vise, or pallet

cradle were out of position, even slightly. If any of these were out of position significantly the

robot gripper could actually crash into it and possibly cause damage and cause the robot arm to

stall. If one of the motors in the robot arm stalls, it will cause the program to abort. If the base is

gripped improperly, it will not be loaded into the CNC vise or on the pallet cradle properly. This



will cause a major failure at the CNC mill or at the assembly station because they do not have

sensors to let them know if the base is in the correct position. This failure could be avoided by

having sensors in the vise (which have been added) and cradle to sense when the base is in the

correct position and also making sure every fixture and machine can not be bumped out of

position.

Another failure mode for the pick-and-place robot is a power failure. This would cause

the robot to stop responding. When power was restored it would then need to be restarted and

recalibrated. Another failure mode could be a signal failure from the PLC to the robot or vice

versa. This will cause a missed signal, which could cause a variety of problems depending on

the signal missed. Problems could range from not starting the CNC to not opening/closing the

grippers. Any of these could cause the manufacturing cell to fail or produce an incomplete part.

The Pick-and-Place robot is shown in Figure 13.

Figure 13: Pick-and-Place Robot



7.1.2 Pick-and-place Robotic Gripper

The grippers are in fact the hand of the robot. In this case, for the Pick-and-Place robot,

the robot has to grab a block of aluminum which is the base part of the product. Therefore, the

gripper must have a wide enough grip to accommodate the part. As mentioned previously, it was

decided to reuse an existing gripper and make some modifications to adapt it to the process.

Figure 14 illustrates the final gripper and the modifications can easily be seen since the gripper is

aluminum. The modifications consisted of: adding a mounting plate to adapt the grippers to the

robot, machining the jaws to increase the opening width of the gripper, and adding a sensor (on

the left part of the gripper) to indicate to the robot whether or not there is a part available to grab.

Figure 14: Pick-and-Place Robotic Gripper


Air Pressur

e

motion


7.1.3 Aluminum Blank Parts Feeder

The blank parts feeder is a gravity feed machine based on a slope with bearings for the

piece to slide on. The blank parts are loaded into the feeder and gravity will settle them into

position. Once a blank is picked up by the pick-and-place robot, the blanks behind fall into place

by gravity.

The original design of the blank parts feeder had a 45 degree slope, this was found to be

far too steep. The parts would slide down at a very fast speed and jump over the piece in front of

it. Another modification needed to be done where the slope on the part feeder changed to a

horizontal surface parallel to the ground. Parts would not slip past the slope. The front of the

piece would just get stuck on the first bearings on the flat. This problem was partly solved by

lowering the slope, but it was also necessary to add three more rods with bearings between other

rods at the transition from the slope to the flat. This allowed the front of the piece not to catch on

the bearings. The last modification was to raise up the blank part feeder. The pick-and-place

robot needed to be raised six inches for clearance with the vise, so the robot arm could no longer

reach far enough down to pick up a blank. So, the feeder was raised 6 inches with a back support

bracket and two side ones.

There are problems that can occur with the blank part feeder. The feeder needs to be

loaded with at least two parts at all times. When only one part is left in the feeder, the slope is

not steep enough and one part is too light to slide all the way to the bottom of the feeder. The

blank parts feeder is shown in Figure 15.



Figure 15: Aluminum Blank Parts Feeder

7.1.4 CNC Mill

The CNC Mill is an EMCO product that was developed a long time ago. This CNC mill

is not as advanced as the majority of CNC mills on the market today. It has limitations in the

programming, the size of the piece that can be milled, and is a manual clamp/unclamp operation.

In terms of programming limitations, the CNC can only handle 300 lines of code for each

program and the program must be saved on a digital mini-cassette that is placed into a tape drive

on the control panel of the machine. The vise that accompanies the CNC mill could not hold a

part more than 3 inches wide and 4 inches high. The manual clamp/unclamp operation also

posed a problem for the project. Therefore, a custom vise was designed and fabricated for this

project. The pneumatic vise will be discussed in detail in another section.

Since a tool change would require too much time, it was determined to only use the CNC

mill to perform one operation. The operation that was chosen was engraving so that ‘RIT’ could

be engraved on the product. However, since a shallow layer of engraving would satisfy the

objectives of the project, a center end mill with a diameter of 3/16th inch was chosen. Therefore,

the program code was designed for a tool with a 3/16th inch diameter. The CNC mill is

responsible for engraving this design into the aluminum base. The CNC mill’s start is controlled



by the Pick-and-Place Robot. Work Instructions for operating the CNC mill are provided in a

User Manual in the Technical Data Package. The CNC mill is shown in Figure 16.

Figure 16: CNC Mill

As with any piece of equipment, there are modes of failure that could occur with the

CNC mill. It is important to perform a FMEA (Failure Modes and Effects Analysis) on any

piece of equipment in order to identify any potential problems that could occur, what the effect

of the failure would be, and how to fix the problem should it occur. Due to the simplicity of the

machine, the CNC will not remember the zero point for a program unless the piece is placed in

that position at the beginning of the program. The CNC can remember in a program the distance

of the tool from the zero point at the start of the program, but the piece must be lined up in that

position or else the machine will run through the program from the position that the part is

placed at. If this failure occurs, categorized as the zero point not being lined up correctly, then

the CNC will begin machining in the wrong area. This could result in a damaged product,

cutting occurring on the vise or the air hose, if one is used, etc. The solution to this problem has

been identified and is the following: measure the starting distance in terms of the x- and y-axis

and cut blocks of wood that fit into the machine from the sides to the vise. This will allow the



operator to verify that the piece is lined up correctly for the start of the program. The correct z-

axis position can be determined by tripping the sensor placed on the top of the CNC machine.

Tripping the sensor will indicate that the tool is in the correct z position.

A second failure mode that could occur is that the digital mini-cassette could become full

and the current program cannot be saved. The best solution to this problem would be to flip the

tape over or insert a new tape and then save the program. However, if both sides of the tape are

full and there are no new tapes, the only solution is to erase the entire tape, input the program

again, and then save the program. This is one of the major negative aspects of working with

such an old CNC machine.



7.1.5 Pneumatic Vise

The role of the vise is to tighten the aluminum base part during the engraving process. It

opens and closes automatically using air pressure. It has been designed with a self-centering

feature that provides repeatability of the process. The vise was built as it had been designed and

only slight adjustments were made once it was tested in the CNC. After testing it in the CNC, it

appeared that vibrations were occurring during the engraving process. If was determined that the

cause of these vibrations were due to the spring and to the radial stroke of the cylinder rod.

Although the spring provides a clamping force, it is an oscillating system with very little

damping. Furthermore the rod of the cylinder was half extended when the vise was closed,

bringing additional flexibility to the overall system. So, in order to fix the problem, a smaller

spring was used on the vise, thus reducing the amount of vibration since now most of the rod is

inside the cylinder. Finally, by adding air pressure to close the vise it adds damping, and mostly

rigidity to the system.

So in fact, the vise was originally designed to be single acting and spring loaded.

However, the final design and actual vise is double acting, but the spring still provides part of the

clamping force and above all it still provides safety to the process in case of air failure. Indeed in

case of air failure, the spring would work on its own, and the result would be that the engraving

will not be perfect, but there would not be any safety issues. The pneumatic vise is illustrated in

Figure 17.

Figure 17: Pneumatic Vise


Air pressure

spring


7.1.6 Pallet Cradle

The blank aluminum piece sits inside the pallet cradle while the pallet travels around the

cell on the conveyor. At the first station, when the block is finished being engraved, it is picked

up and placed into the pallet cradle. The pallet cradle then moves along the conveyor to Station

2 where the swivel pen holder is assembled onto the engraved piece while it is still in the pallet

cradle.

The final design of the pallet cradle is quite different than the original design. The pick-

and place robot needed to be raised 6 inches because of clearance issues with the vise, so the

pallet cradle also needed to be raised 6 inches. This is a significant change from the corner

pieces used in the original design. The new design is a 4.8”x7.6”x2” machined block with a

cutout in the shape of the block, 0.5” deep. Two sides of the pallet cradle are machined 0.5”

deep, so the gripper on the pick-and-place robot has room to grab the aluminum blank.

7.1.7 Finished Goods Bin

The final location for a piece that has been created in the automated cell is the Finished

Goods Bin. The finished goods bin is a way for a completed part to be taken away from the cell

so the end user can easily access it. Considerations were given to space, financial, and material

property constraints.

For the particular task of building the pen holder, a design for a finished goods bin was

constructed to fit in between the conveyor and the main outer tabletop. The double two by four

frame stands approximately three feet tall, and supports a four foot by one foot tray that is angled

74 degrees off the stand. These were all chosen to be wood. On top of this rectangular four foot

by one foot tray sits a plastic track with plexi-glass and aluminum walls that reduces friction

enough for a finished pen holder to be swept away with gravity. A tapered 90 degree curve was

implemented at the end of this three and a half foot track to slow and stop the piece at a location

accessible to the end user.

The shape of the finished goods bin was chosen because of the limited space of the cell,

and the mobility of the robot arm. The only location that the robot could place a finished pen

holder was at such a place where a bridge would have to be built over the conveyor. This

requirement was address by the four foot by one foot tray that extends up and over the conveyor

and starts in a position close to the robot arm. The frame was also “thinned” down to fit in

between a tight space between the conveyor and an immovable front table.



The material of wood was chosen because of the very low financial burden it carried.

The feet, the stand, the tray, and the cross supports were all made by the design team from wood.

Screws and nails were used to fasten it all together.

The track was made from a pre-fabricated plastic mold. This was well suited for the

finished goods bin because the plastic created a very low coefficient of friction between it and

the aluminum when sliding at a 74 degree angle, and the pre-fabricated curve required no

additional modification at the end of the track.

From the design board to the finished product, the finished goods bin construction went

as planned. If modifications were to occur, they happened before anything was fastened. Case

and point, the angle of the four foot by one foot tray was tested at several angles to judge the

optimum speed the pen holder needed. The finished goods bin is illustrated in Figure 18.

Figure 18: Finished Goods Tray



7. 2 Second Station

The second station consists of the Assembly robot. The pallet stops on the conveyor in

front of the robot and the robot retrieves a pen holder swivel from the feeder. The robot

assembles the pen holder swivel onto the engraved aluminum block. The pallet then moves

along the conveyor back to Station 1 for the finished part to be unloaded.

7.2.1 Assembly Robot

The Assembly Robot utilizes a program to do its task of assembling the swivel pen holder

to the engraved aluminum base. The assembly has a parallel pneumatic gripper attached, which

grabs the next available swivel pen holder. The robot is only able to grab from above.

The program that runs the assembly robot checks to see if a pallet has arrived by

receiving an input signal. The robot then finds the next available pen holder by checking each

spot for a pen holder using a light sensor, then moving on to the next spot in the pen holder

magazine. Once an available pen holder is found, the robot uses its pneumatic gripper to grab

the pen holder. The robot'sarm then moves to the pallet to attach the pen holder to the engraved

aluminum base. An output signal is then sent to allow the pallet to move on the conveyor. The

robot is now available for the next pallet to arrive.

The original design of the assembly robot'smovements to the final design has not

changed much. The only alteration to the original design was for a sensor attached to the

pneumatic gripper finger to send a signal to the robot if a swivel pen holder is available in the

position the gripper is currently at in the pen holder magazine. This allows for the magazine

feeder to only have one swivel pen holder loaded and assemble it. With the original design, the

robot started at position 1 in the magazine and grabbed for a swivel pen holder whether one was

loaded or not.

Possible problems with the robot would be if anything is obstructing the path at which the

robotic arm swings. This is overcome by making sure the area around the robot is clear before

running it. Another problem can occur when in the previous run of the robot, the e-stop was

pressed. The program will not run if this happens. The operator needs to check if the e-stop

button is still pressed it and if it is, release it. Station 2 is illustrated in Figure 19.



Figure 19: Assembly Robot, Station 2

7.2.2 Pen Holder Robotic Gripper

The pen holder consists of three components, the angular pneumatic gripper and two

aluminum fingers. The angular gripper opens and closes two small 0.25”x1”x0.25” adapters in

an angular motion. The aluminum fingers attach to the adapters. Half of the profile of the

swivel pen holder is machined into each finger, so when the two fingers close, the fingers grab

around the swivel pen holder.

The original design called for a thin rubber coating on the profile in the fingers to grip the

swivel pen holder better. The rubber coating was found to be unnecessary.

For the fingers to grab the profile of the swivel, the swivel pen holder needs to

approximately vertical. If the swivel is not vertical enough, the gripper might not grab the swivel

right or even crush the swivel.



7.2.3 Pen Holder Fixture

The pen holder fixture is a 14”x5”X2” rectangle block consisting of 2 rows of 5 square

holes. The squares holes have a square 1/8” lip on them. Each lip hole holds one pen holder

with the adhesive cover peeled off the bottom of the pen holder.

The original finished pen holder utilized 2 swivel pen holders per blank part. Therefore,

the original pen holder fixture was a 12”x12”x2” square block with 4 rows of 4 square holes.

Sixteen swivel pen holders loaded into the fixture at one time, seemed too much so this was

decreased to ten in the final design.

A problem that can occur with the pen holder fixture is that if any swivel is not loaded

into the magazine as vertical as possible, then the gripper might not grab the swivel pen holder

right and crush a pen holder or even stop the program. It is necessary to load the swivels, with

the tops vertical and also to check that previously loaded swivels were not bumped before

running the cell. The pen holder swivel feeder is illustrated in Figure 20.

Figure 20: Pen Holder Swivel Feeder



7.3 Electrical Aspects of Cell

The primary challenge of the electrical system that needed to be designed for this

manufacturing and assembly cell was to provide a system that could interface with each of the

four major components of the cell and monitor the activity that is taking place at each location.

It was decided that a central control system was needed to control the communication between

each of the subsystems and to provide feedback. A final requirement of the control system was

that the system needed to be action based; meaning that no processes within the cell could take

place without the controller first receiving a signal from the previous process that it had been

completed.

7.3.1 Discussion of Programmable Logic Controller (PLC)

A PLC is a dedicated microprocessor that can be easily programmed to realize several

types of control. The PLC that is used in the cell is an OMRON CQM1H CPU21, and has two

16-Inputs modules and one 16-outputs modules that are on the main unit. The language used to

program the PLC is ladder programming. This language is not explained in this report but it is

very logical and straight forward.

Figure 21: Programmable Logic Controller

There are many uses for PLCs, but the way it is used for this cell is the simplest way:

basically it deals with a bunch of inputs and outputs, and depending on the inputs state, the

logical program loaded into it will dictate how to set the outputs. The inputs are a series of

sensors and the outputs are pneumatic actuators and signals to synchronize the different devices.

Initially, the PLC was running the conveyor dealing with the gates, and all the

pneumatics devices like the lifts at the different stations. Now, since the process is different

from the previous utilization of the cell, the logic must be changed in accordance with the

process flow. The majority of the team’s time spent working on the PLC focused on the

software and the rest was hardwiring the network to get the required signal to the input ports.



The program in the PLC is very simple since it was decided to limit its control to the

conveyor. Indeed the robots have features that provide the ability to control several inputs and

outputs. Therefore, in order for each sub-process (assembly, engraving) could be run

independently to make it easier for testing purposes, each robot controls the sensors and the

actuators that are related to its process. It is important to note that once programmed, the PLC

runs on is own, and its use is completely transparent for someone whose operating the cell.

However, it is a very reliable device.

7.3.2 Interfacing Issues

Interfacing the manufacturing cell proved to be a challenging and time consuming task.

The whole electrical interface system was designed to operate on a 24VDC circuit and all

sensors used in the cell were of industrial quality that were specifically designed for the

manufacturing environment. Therefore, this prevented the possibility of flaky unreliable semi-

conductor components from becoming a factor in the debugging of the manufacturing cell and so

the root cause of most of the electrical problems within the cell was the result of faulty wiring.

The biggest challenge of interfacing the cell was wiring all of the signals to the correct

location. It was very important to verify that each sensor output was wired to the correct robot

and PLC inputs. Most electrical problems with the cell were the result of a wire being

improperly connected. It was discovered that if an electrical signal was suspected of not

properly working, to first check the signal connections in the white junction panel mounted

under the conveyor.

There are several failure modes that could occur with the cell. These failures have been

identified and solutions recommended. First of all, if a sensor is not working, check if power is

being provided to it. All sensors in the cell have LEDs that indicating that power is provided to

it. Next check if the sensor is sending an output signal when it is tripped. If the sensor is

directly connected to one of the Adept robots, enter the command “IO” at the command prompt.

This command scans the status of all of the digital I/Os to the robot. For details on this

command refer to the Adept Controller manual. If when the sensor is toggled none of the inputs

on the robot IO display are toggling between 1 and 0, then the third signal wire from the sensor is

not properly connected.

If none of the sensors in the cell are receiving power and the PLC is not powered, then

the 24VDC power supply is off. If the blacked handled switch on the gray junction box has been

verified that it is in the one position, the fuse 24V circuit fuse has been blown. This fuse is



located inside the gray panel in the lower right hand corner next to a large blue capacitor. When

replacing the fuse, be sure that power is off and the capacitor has been discharged.

If the PLC is not responding to inputs or sending outputs to the system, check that the

input and output modules are firmly mounted to the PLC controller. If the I/O ports are not

pushed all the way into the controller, proper contact will not be made.

7.3.3 Programming Issues

The challenge of programming machines that interact with an outside environment is

detecting changes in the environment that the machine is not directly controlling. To meet this

challenge, the manufacturing process was set up to be an action-based system, meaning that a

new process does not start without first receiving an input signal informing it that the previous

process has been completed successfully and is ready to start the next task.

The pick-and-place robot by far had the most interactions and possible errors to monitor.

To provide feedback to this robot, numerous proximity sensors were used to monitor the

movement of a part. A sensor mounted at the bottom of the aluminum base blank feeder

informed the robot when the part feeder was out of parts and prevented the robot from trying to

move a part that was not there. For the robot to properly place a part in the CNC milling

machine vise, the vise needed to be open. For this reason, the signal for the air solenoid

controlling the opening and closing of the vise was wired directly wired to an output of the robot.

Also for the part be properly placed in the CNC vise the slides and milling head needed to be in a

certain position as to prevent a collision from occurring if the robot moved in at the wrong time.

Therefore, two more proximity sensors were mounted on the milling head and cross-slide to

assure the machine was in the proper position. Another sensor was placed inside the vise to

insure the aluminum blank was properly clamped. If the part was not properly clamped, a

collision of the CNC tool and the aluminum blank would take place.

One more proximity sensor was mounted on the gripper of the pick-and-place robot to

check for finished parts on a pallet. At this station there is the possibly of empty pallets waiting

for a machined base and pallets with a finished part waiting to be placed in the finished goods

bin arriving at the same location. To determine if a finished part is in the pallet the proximity

sensor on the gripper will detect a part during a checking routine.

At the assembly robot location, the process is the same and repeats. However, due to the

difficult geometry of the pen swivel funnels a part feeder that indexes the next funnel to the same

location was not feasible. Therefore, the funnels are loaded into a tray and the robot indexes to a



new location after each assembly to obtain the next funnel. The problem with this setup is that if

one location does not have a funnel the robot will allow a base to be assembled without a funnel

mounted. To detect a missing funnel a photo-interceptor diode sensor was mounted on the side

of the gripper. This type of a sensor consists of two parts, an emitter and receiver. The emitter

mounted on one side of the gripper emits a continuous beam of light at 890 nm. On the opposite

side of the gripper, the receiver is mounted and it detects the beam of light. Whenever an object

passes between the emitter and receiver, the beam of light is interrupted. The receiver detects

this interrupt and sends a signal to the robot telling it that there is a funnel at that location in the

part feeder.



8 Simulation Model

The customers of this project would like to use the finished cell as a demonstrative tool

for classes as well as tours for prospective students. The cell not only displays how certain

machines work individually, but also how they can be interfaced to work together. The team has

decided that it would be in the customer’s best interests if an Arena simulation model were also

provided with the project. One of the main advantages of modeling the system is that the

simulation can be used in settings other than the Brinkman Lab, such as the classroom. This will

allow the customers or any other faculty member to demonstrate how the cell works without

actually having to run the machines in the cell. The model will provide a visual representation of

the process flow and how the various machines will interact with each other. A screenshot of the

animation for the model can be seen in Figure 22.

Figure 22: Simulation Animation

The simulation model can also be used to analyze the process flow of the cell. The model

can test various changes in the system to optimize the cell’s efficiency. The program could also

be quite powerful to test an assortment of potential “What If” scenarios for the future. The

model will be capable of showing what effects result from any change in the system without any

physical implementation. For example, if the customers of the project decide at a later date to

change the final product or add another machine to the cell, these changes can be made in the



simulation. The model can then be run with the new constraints and the results of the changes

can be analyzed.

The simulation logic begins by creating the number of pallet entities chosen by the value

of a NumPallets variable at the simulation time zero. These entities are each assigned a specific

picture to resemble the pallets and they then access the conveyor. These entities enter the system

at the CNC station. This Arena station represents the location of the first pallet station on the

actual cell’s conveyor across from the pick-and-place robot and the CNC machine. Nine part

entities are also created at time zero and assigned a different picture. These parts are sent to a

BlankParts queue that represents the fixture to release the aluminum base to the robot. The

capacity of the actual fixture is nine pallets so the simulation logic was created to represent this

actual capacity.

While all of this is going on, another part entity is created at time zero and sent to a scan

block. The entity is held there until only one part remains in the BlankParts queue, at which time

the entity is duplicated eight times. The eight duplicates will enter the BlankParts queue and the

original will loop back and wait for the same scan block again. This logic is based on the

assumption that if the cell is run continuously, the parts feeder will be replenished before it runs

empty.

When the pallets arrive at the first station, the pallet entity scans to make sure there are

parts available and then seizes the pick-and-place resource. The part is then delayed to simulate

the movement to the CNC, a part is picked up, and the CNC resource is also seized. When the

part has completed its processing, it is returned to the station, the resources are released, and the

pallet/part are conveyed to the assembly station. Similar to the first process, the entity seizes the

assembly robot resource and a delay occurs to represent the assembling of the pen holder to the

engraved aluminum block. After assembly, the part is conveyed around the backside of the cell

to the CNC station once again. Here the finished part is removed from the pallet and placed onto

a Finished Goods tray. The pallet, however, remains on the conveyor to pick up a new part and

the cycle continues. A screenshot of the model code itself can be seen in Figure 23.



Figure 23: Simulation Model Logic



9 Recommendations for Optimization

The mission and goal of this project and this team was to integrate a manufacturing and

assembly cell that would produce a desktop pen holder. With disciplines of mechanical

engineering, electrical engineering, and industrial engineering the design project team was able

to complete the main goal. Furthermore, the goal of creating a teaching tool for Industrial and

Systems Engineering courses as well as demonstrations on tours was met.

The ability of the team to organize and track the steps that went into the production of the

manufacturing and assembly cell is of great use for operation of the cell as well as evolution of

the cell. From the start, the project was known to be a base for future projects in the ISE

department, and steps were taken to assure this occurs.

The next step for this cell lies in the hands of its stakeholders. With the hope of future

progress there are a few recommendations the team would like to share. A prime concern is the

physical safety of the cell. Since the Brinkman Lab is the location of the cell, and the Brinkman

Lab is shared by many other faculty and students, there are cases of foreign objects from others

obstructing the user interface or the cell movements. A difficult but necessary task would be to

inform participants in the Brinkman Lab of the delicacies of the manufacturing and assembly cell

to assure cell safety as well as keep a professional appearance of the cell.

Yet another recommendation is to upgrade the technological side of the cell. From

processor speed of the robot computers, to storage capacity of the CNC machine, a higher

efficiency of work could be achieved with higher quality tools. This is a costly element, but the

funds put in would be clearly shown in future products.

Last but not least, the cell could be a daunting task to operate. The team recommends a

set of detailed work instructions, provided by the design team, be left at the cell at all times, as

well as electronic forms of the instructions available whenever necessary.



10 Conclusion

All of the customers’ requirements were successfully met with the completion of this

project. The cell is functioning properly so the customers can begin to use it for demonstrations

and ISE courses. The final engraved desktop pen holder is a product that could be given as a

souvenir to prospective students visiting the Industrial and Systems Engineering Department.

Now that the machines are integrated, the customers could at some point change the product to

be manufactured and assembled in the cell with minimal difficulty. The Arena Simulation model

was an order winner of the project and will prove to be very beneficial to the customers for

demonstrations of the cell in an environment other than the Brinkman Lab. The integration of

the manufacturing and assembly cell truly utilized the disciplines of industrial, electrical and

mechanical engineering.


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