Lecture 13: Detailed Design: Prototyping & Design for ...mech350/Lectures/MECH350-Lecture-13.pdf ·...

1

MECH 350Engineering Design I

University of VictoriaDept. of Mechanical Engineering

Lecture 13: Detailed Design:

Prototyping & Design for Manufacture

© N. Dechev, University of Victoria

2

PROTOTYPINGDESIGN FOR MANUFACTURING (DFM)DESIGN FOR ASSEMBLY/SERVICING

Outline:


Detailed Design-Detailed Analysis-Simulate & Optimize-Detail Specifications-Drawings, GD&T

3

Detailed Design within the “General” Design Process


Identify Need-Talk with Client-Project Goals-Information Gathering

Conceptualization-Brainstorming-Drawing/Visualization-Functional Decomp.-Morphologic Chart

Preliminary Design & Planning-Prelim. Specifications-Prelim. Analysis-Decision Making-Gantt Charts & CPM

Report/Deliver-Oral Presentation-Client Feedback-Formal Design Report

Prototyping-Prototype Fabrication-Concept Verification

Testing/Evaluation-Evaluate Performance-Are Objectives Met?-Iterate Process Steps 2 - 7 as needed

Problem Definition-Problem Statement-Information Gathering-Design Objectives(quantifiable/measurable)

4

A Prototype is an early stage/version of the design, intended to prove/validate/test the design idea, and communicate the design idea to both the design team and clients.

Prototyping is a highly important activity in the design process.

At some point, the design team must construct a prototype to:Prove the design functions as intendedMeets the main/key objectivesCommunicates the initial design concept to the client/customers

Prototyping


5

There are many different types of prototypes, with different purposes:

Alpha, Beta, ... Prototypes- May involve cardboard cutouts, wooden shapes to illustrate form and shape.- May or may not function.__________________________________

Proof of Concept Prototypes- prove the idea/concept itself, but have the wrong shape or do not embody the appearance.__________________________________

Prototyping


6

Visual/Scale Prototypes: - will often involve “Industrial Design”, or “Artistic Design”- Do not function

Prototyping


Audi RSQ Concept Car 2004 [http://robson.m3rlin.org]

7

Functional Prototypes:To the best practical extent, attempt to simulate the final performance, function, aesthetics and materials of the intended design. The word practical refers to: cost, time and resources.

In MECH350 it is expected that you achieve a Functional Prototype for the Major Design Project.

Functional Prototype Construction


8

The following slides will give you practical tips for the construction and fabrication of a Functional Prototype.



Example Prototype Device, by Rodney Katz et. al. [1]

9

1) Communicate with and visit the machine shop/facility where the prototype will be constructed. Learn:

- capability & availability of staff- capability & availability of machines- establish a schedule of activities- establish the costs for use

2) Create a list of prototype materials and determine:- availability locally or special order- lead time to acquire after ordering- costs- machinability at machine shop



10

3) Use standard material sizes within your prototype where possible:- This minimizes costs, time and effort- Example: Use standard wood sizes like a 2x4, instead of 1.6”x3.75” (unless it is functionally necessary/critical)- Example: a standard 3 mm or 6 mm Aluminum plate, instead of 2.75 mm (unless it is functionally necessary/critical)

4) Use standard tool sizes for machining where possible:- Example: use 1/8” drill bit, instead of 1.15”

5) Use standard fasteners to assemble the prototype.- Avoid exotic fasteners, and use easily obtainable types- Example: use 8-32 bolts, 10-32 bolts, 1/4-20 bolts, etc... for ease of availability, low cost, etc...



11

6) Use the same fastener type as much as possible (to minimize different types):

- Example: use only 10-32 bolts throughout for ease of interchangeability.

7) Consider using Plastics or Wood instead of metal where possible:- Easy and quick to machine.- Low cost and plentiful- Easy to repair/modify without re-machining entire part.



12

8) Build an Aesthetic Prototype and design/plan for it accordingly.- NEVER underestimate aesthetics!- Acknowledge human nature of “First Impressions”.- A good/smart looking, polished prototype makes a huge impression/impact on:

- clients- investors / financiers- public and other stakeholders



13

Examples of Aesthetic Prototypes



POOR: Image of “Final Prototype” as Presented and provided in Final Report

GOOD: Image of “Final Prototype” as Presented and provided in Final Report

14

9) Create a ‘Prototype Cost’ budget:- This is not a market-value based budget.- Create a spreadsheet of:

- Item with #, and description- Estimated shipping time (days).- Quantity in units, length, area, or other.- Cost per unit, sub-total per item, and Total cost.- Shipping, Taxes and Duty (if applicable)

10) Sourcing Prototype Parts:- The MECH 350 website has a number of useful suggestions and links to various “mechanical and electrical” parts suppliers.http://www.engr.uvic.ca/~mech350/Core-Files/Supplier-Info.html

- Where possible, consider the use of “surplus parts”, which are often new/unused parts, that are simply discontinued.



15

11) Making Use of Purchased Parts in Prototypes:- Always ensure you have a data sheet, specification sheet or drawing for any parts you use in a prototype, specifically:

- Physical Dimensions (length, weight, etc...)- Performance (strength, electrical, etc...)

- Without such information, using parts (new or surplus) can be frustrating, like trying to extract dimensions or performance parameters, from actual parts which you know little about.

12) Testing and Re-work:- Give yourself ample time for testing of the prototype.- It never works the first time, so develop a ‘test plan’ into your design work and plan for testing accordingly.



16

An excellent document prepared by our research machinist, Rodney Katz [1] , is available on the MECH350 website: http://www.engr.uvic.ca/~mech350/MECH350-Prototype-Design-and-Manufacturing-Manual.pdf

This document was written with the machine shop’s perspective, and offers excellent ideas/recommendations to students on preparing prototypes.

Functional Prototype Construction:Machining Suggestions


17

DESIGN FOR MANUFACTURING (DFM)DESIGN FOR ASSEMBLY/SERVICING

Outline:


18

Design for Manufacturing, is a method to design products/components/parts in such a way as to make them easy (i.e. inexpensive and quick) to manufacture.

Many “mass produced” products incorporate the DFM method, such as:

automobiles__________________________________computer chips__________________________________soft drink bottles/cans__________________________________

Design for Manufacturing (DFM)


19

Consider again the “structured design process” of this MECH350 course. We are learning to apply the following design process:

Needs/Goal StatementsMission StatementInformation GatheringObjectives/ConstraintsConcept Generation ProcessSelection Method for ConceptsDetailed DesignPrototype ConstructionTesting and Evaluation (and Re-Design as required)Documentation & Communication of Final Design



20

Given our “structured design process”, it becomes relatively simple to incorporate “Design for Manufacturing” into engineering designs.

This is simply done by adding/including the desired “Manufacturing Concepts” into the design process. Specifically, including them at the following stages:

Goal StatementsObjectives/ConstraintsSelection Method for Concepts



21

Consideration of manufacturing concepts at an early stage in the design process is key.

By placing DFM ideals your “goal statement”, its importance will trickle down throughout various aspects of your design.

By listing key DFM Objectives, to design will be “altered/skewed” towards ease of manufacture.

Also, buy using DFM ideals during concept selection activities.

NOTE: DFM will alter your otherwise “ideal design”. However, ideal designs can be difficult, or even impossible to manufacture. Hence you must find a balance between the ideal design and an easily manufacturable design.



22

DFM in the “goal statement”:______________________________________________________________________________________________________

DFM Objectives:______________________________________________________________________________________________________

DFM in the concept selection process:______________________________________________________________________________________________________

Example: DFM for a Portable Drill


23

Some typical DFM Objectives to consider for designs include:Material__________________________________Geometrical features/shape__________________________________Speed/time to manufacture__________________________________Equipment for manufacture__________________________________Minimum # of parts__________________________________Assembly complexity/process__________________________________Other:__________________________________

Typical DFM Objectives


24

Design for Assembly (DFA), can be considered as a corollary to DFM.

DFA is method to design products/components/parts in such a way as to make them easy (i.e. inexpensive and quick) to assemble.

Statement for discussion: “The costs/time associated with the assembly stage of manufacturing result in zero (or less) monetary gain for manufacturers.”

Consider the business strategy/model of:__________________________________

Design for Assembly/Servicing


25

Similarly, you can implement DFA by including Assembly ideals into your design process at the following stages:

Goal StatementsObjectives/ConstraintsSelection Method for Concepts

Similarly, DFA will alter your otherwise “ideal design”. Hence you must find a balance between the ideal design and an easily assembleable design.

Design for Assembly/Servicing


26

The following examples are taken from a DFA course by Ken Youssefi [1]. Note, more examples are available in reference link.

Examples of DFM and DFA


Ken Youssefi, Reference [1]

Example 2: Modularize multiple parts into sub-assemblies

________________________

Example 1: Minimize # of Parts________________________________________________


27




Example 4: Design for easy assembly & access for service

________________________

Example 3: Standardize parts to reduce variety

________________________


28




Example 6: Design for easy assembly & access for service

________________________

Example 5: Implement “self alignment features” and snap-joints, to minimize # of fasteners

________________________


29

[1] R. Katz, M. Lewis, “Prototype Design and Manufacturing Manual”, Machine Shop, Dept. of Mechanical Engineering, University of Victoria, 2010.

[2] K. Youssefi, “Design for Manufacturing and Assembly”, UC Berkeley, online PDF at: http://www.me.berkeley.edu/ME110/presentations/DesignForManufacturingAndAssembly.pdf, referenced online on Mar 1, 2011.

References for DFM and DFA


Date post:	12-Sep-2019
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

Lecture 13: Detailed Design: Prototyping & Design for ...mech350/Lectures/MECH350-Lecture-13.pdf ·...

Documents