FINAL REPORT

EMAIL

309-6350 Stores Road, Vancouver, BC V6T 1Z4

UBC Materials Engineering MTRL 466/467 Final Design Project Report

Thermoforming of Thermoplastic: Proposed Improvements to Design Variability and Socioeconomic

Effects (Stage 1) Joey Pateman 77342095

Harith Fauzi 18204115 Narain Khera 44992105

Tyler Lightfoot 25103110 Brandon Lingard 20846119 Kennan McGrew 55398101

Jan Vreys 23043128

Professor Chad Sinclair

Due: November 24th 2014

Thermoforming of Thermoplastic: Proposed Improvements to Design Variability and Socioeconomic Effects (Stage 1) 2

Design Report

Executive Summary (In one page summarize the salient points of your work)


Design Report

Problem Definition (general background to the project which must identify customers or users, the need for

the design and any applicable constraints. This section should not exceed 2 pages.)

Introduction

This report details the benefits and constraints of a new thermoforming design process project, where heated air is used to form a

pattern into a thermoplastic sheet. An architect, Blair Satterfield, along with colleges have determined a way to improve the

functionality of a thermoplastic sheet by creating specific patterns within the sheet itself. Blair seeks outside consultation to

improve upon his teams’ initial design processes (See: Background for further details) in terms of variability and precision of design,

portability, and costs. The process must uphold certain specifications.

The goal of this project is to compare Blair’s previous design process to this proposed Heated-Air-Compressor method. This section

provides a background to the project, process specifications and project goals. The report continues on to summarized research of

the advantages and disadvantages of using a thermoforming process to form a thermoplastic to form a better understanding of the

material being worked with as well as provide a wider array of ideas for a design. The next step involved brainstorming design

options and singling out the best option for this specific project. Next, rough parameters are given through thermal and mechanical

modelling to prove the chosen design is feasible. A comparison is then measured through environmental impact and economic

(costs of process, materials and equipment) means.

Background

Blair Satterfield is an architect and assistant professor of architecture at the University of British Columbia. Blair’s professional

practice (along with Marc Swackhammer), named HouMinn Practice[11], focuses on research-based design seeking collaboration with

experts outside the field of architecture. HouMinn strives to utilise digital production and fabrication techniques in housing and

urban landscapes.

Blair’s idea began with expanding the function of walls. Can we give walls extra functions that are difficult to obtain with traditional

building materials? A program was created to place patterns within these wall patterns to provide a specified function. The theory

behind the pattern formation relies on the basic drawing techniques: stippling and cross-hatching (See Appendix A – Figure 1),

where stippling relies on points for image formation, and cross-hatching relies on lines. Hence sheet designs would revolve around

these basic techniques. Lines and/or points (or bubbles) developed varying in geometries and positions within a thermoplastic

sheet. Note, this report will refer to the formation of a line/bubble within a sheet as a deformation.

Blair and his team began experiments to test the viability of the concept. The VarVac (Variable Vacuum forming) project (See Figure

1 below) involved forming wall panels with the ability to sound dampen a busy office. This design relied on the deformations of both

bubbles and lines in a polystyrene sheet (See Figure 1 below). The program specified the geometries and positions of the shapes for

multiple wall panels to create the noise-dampening wall. In the Core77 2014 Design Awards Program, VarVac won The Professional

Runner-Up Award – gaining attention from all around the world [10].


Design Report

Figure 1 – The finished VarVac project: this wall is composed of many wall panels (left); One wall panel: the original flat polystyrene sheet has been molded to form

deformations of lines and bubbles [Note: after drying the bubbles have been cut] (right).

Descriptions of the processes Blair and his team used to create these wall panels can be found in the Technical Review Section of the

report. The advantages and disadvantages to each process form a better idea of the aspects of the process that will need

optimizing, described in Proposal Specifications and Project Scope.

Proposal Specifications and Project Scope

In first understanding the goal at hand, it was important to define the scope of the project in terms of (1) the responsibilities of the

team, (2) the project constraints and specifications, and (3) a reasonable scope of accomplishment for the three month duration of

the project.

(1) The process proposed in this report focus’ on the ability to create a wall panel, allowing variability in design as specified by

the customer, Blair Satterfield. However, this project will not cover the functions of the designs in the wall panel, and will

focus solely on the designs of a specified thermoforming process. The team makes the assumption that Blair is able to

create functions in the wall panels via specified deformation geometry and positions of the pattern using this

thermoforming process.

(2) In this project, the customer requires an optimized and simplified manufacturing process to mold a thermoplastic sheet

through thermoforming. Optimizations of the process will be measured through time it takes to form the pattern in the

sheet as well as economic and environmental comparisons to Blair’s vacuum forming process. The vacuum forming

process is used as a comparison because Blair emphasized it as his main process. The process should be simplified to the

extent it is portable and easy to operate (minimal training necessary). Molding geometries of the sheet should be able to

deform the thermoplastic to the shape of a line. A line is the simplest form of deformation to model to prove the viability

of the process. This line is to have as much variability in geometry and position on the sheet as possible. (picture)

(3) Provided a short time-line with such a large task, this project focuses on proving the viability of the proposed process and

whether this process is an improvement to the vacuum forming process Blair’s team used (Stage 1). Take note,

reasonable assumptions have been made in order to thermally and mechanically model the process in this short time

frame. Recommendations are provided at the end of the report to detail the next Stages the project requires given

further time and resources.


Design Report

Technical Review (Review the prior art relevant to the design task, provide relevant scientific background

information, and critical assessment of the literature. This section should not exceed 5 pages.)

The customer, Blair Satterfield, has requested a thermoforming process using thermoplastics. To fulfill Blair’s request (See Problem

Definition), technical understanding of the properties of thermoplastics and thermoforming process is necessary. Technical

understanding of the properties describes the limitations of the forming process or materials.

This section is split into the main categories of Processes and Materials. First, researching an array of thermoforming processes will

aid in brainstorming ideas that can optimize Blair and his team’s initial experiments. Next, researching thermoplastics properties will

provide an understanding to the benefits and restrictions of the material being deformed.

Processes: Various Plastic Forming Methods

A wide variety of heating and molding methods are used to form different shapes and patterns for polymers.[6] A few are described

below:

Vacuum Forming (See Appendix A – Figure 2) – A sheet of thermoplastic is clamped over a mold, softened by heating, and a vacuum

removes the air between the sheet and the mold. This causes the heated sheet to be sucked down onto the mold, taking up the

shape of the mold. Molds are generally expensive, allow for poor variability and aren’t portable.

Blow molding (See Appendix A – Figure 2) – Polymer blanks are heated and expanded with compressed air, like a balloon, inside a

mold to create the finished product. This process is generally used to create hollow shapes such as soda bottles, milk cartons, and

gasoline containers.

Press forming (See Appendix A – Figure 2) – Involves the use of a large, 2-sided die to press the material into the desired shape. This

process is generally used to make storage containers, small packaging containers, etc.

Extrusion molding (See Appendix A – Figure 2) – Polymer (in the form of pellets) is heated to a viscous state, and pushed with

pressure through a small die. This process is continuous and is used to make things like piping (See Appendix A – Figure 2).

Narrowing the forming processes using basic constraints given by the Customer, all large-scale and fixed-mold processes are

eliminated (a portable, variable process is required). Only vacuum forming is left on this list (Note: although vacuum forming has a

fixed mold shape, it can be pre-manufactured in any design at a relatively low cost).

Processes: Initial Experimentation

After reviewing the various forming techniques, the next step involves further understanding the thermoforming processes that Blair

and his team undertook. Thermoforming is a manufacturing process where a thermoplastic is heated above a specific temperature

and molded to a desired shape (See Materials: Why thermoplastic?). Understanding the advantages and disadvantages for the

processes that already achieved the project goal will make it easier to understand what can be optimized in order to create a new

and improved thermoforming process. To create designs in the panels, Blair’s team used various methods to heat and deform the

polystyrene thermoplastic. Note that most of this section references Blair himself through presentation, discussion and email.


Design Report

Vacuum Forming

Vacuum forming (See Appendix A – Figure 2) was one of the initial forming techniques used. This method involves heating the

sheet, placing it over a pre-manufactured mold, and removing the air from between the sheet and mold.[6] By removing the air, the

heated sheet is forced to form to the details of the mold. Some disadvantages included vacuum leaks (leading to imprecise forming),

bulky equipment (decreasing mobility at job sites), and pre-manufacturing molds (decreasing variability of shape and increasing

costs).

As Blair explained, in an attempt to improve on the last process, the mold was redesigned. Hexagonal shaped bars stacked side to

side, in a vertical orientation each able to vary in height allowed for more variation in shapes (See Figure 2). This method provided

higher resolution of shapes and less material waste. Unfortunately it was slow, could only be efficiently controlled with one sheet

thickness, and required specialized equipment available only in their machine shop.

Wire and Gravity Forming Process

To simplify the process, Blair and his team tried to eliminate the mold altogether. A wooden support was constructed upon which

wires were laid out in the desired pattern (See Figure 2). The polystyrene was heated and allowed to droop through the holes

formed by the wires –imposed forces were due to gravity only.

Blair and his team found a few difficulties with this process:

Understanding how long to apply heat with the sheet underneath the heater took much trial and error. There was a very small

margin of error between no deformation at all and a ripped sheet. Many parameters needed to be controlled for heating (i.e. the

distance the heater is from the sheet, the relative intensity of the radiation, forming environment, etc.).

During forming, the edges of the sheet deformed and further separated from the plywood mold. It appeared that as the sheet

stretched after heating, the sides pulled in and away from the edge of the mold. This created a non-uniform border. Without the

ability of an adequate clamping system, the customer mitigated the issue by using larger sheets and trimming the formed sheet back

to square however, this isn’t as cost effective as it could be.

The mold itself also caused issues during forming as it was made of plywood. The mold starts to smolder if left in the radiant heat for

too long, and during heating, the screws holding up the metal wires began to come loose.

Figure 2 – VarVac thermoforming processes: Hexagonal mold (left); Wire and gravity (right).[9]


Design Report

Materials: Why Thermoplastics?

The materials initial literature review’s aim is to determine what properties of thermoplastics would make them more desirable for

this forming process (See Problem Definition). First, a comparison between different polymer types is made. Polymers can be

grouped into three main categories; elastomers, thermosets, and thermoplastics (See Figure 3). [6]

An elastomer is a general term given to polymers that display viscoelastic properties, usually modeled by a spring and dash-pot

combination.[6] At room temperature an elastomer is able to return rapidly to its original form upon facing a substantial

deformation imposed by a weak stress.[12[ On the microstructural level, it is composed of long molecular chains, with many cross-

links to form a 3D network.

Thermosets is a material that, generally after heating, cures/sets into a given shape.[6] This reaction/molding is irreversible. This can

be explained on the microstructural level: during curing the network of small polymer chains tangled and cross-linked to each other.

These cross-links are strong bonds, hold the chains to each other, and are not broken easily. This feature provides them with

thermal stability and durability. However, since they cannot be softened and reformed, they cannot be recycled or reused.

Thermoplastics are similar to thermosets in that they are made of polymer chains, however they can be softened and reformed via a

glass transition temperature.[6] Molecular chains are intertwined and tangled, and held in position by secondary bonds known as

Van der Waals forces. Van der Waals forces are weak enough that, when reaching a specific temperature (varies among different

thermoplastics), enough energy is provided for the bonds to break. This temperature is named the glass transition temperature.

The chains can now slide past each other, providing the polymer viscoelastic properties and allowing molding abilities. Note, the

energy at glass temperature is not strong enough to break the strong covalent bonds within the individual molecular chains. When

the material cools to crystallization, the polymer chains again become intertwined and tangled by Van der Waals forces. The effect

of temperature on thermoplastic can be further demonstrated on graphs in Appendix A – Figures 3 and 4.

Figure 3 – Microstructures of polymers: Thermoplastic (left); Elastomer (middle); Thermoset (right).

The project process requires reformation of polymer sheets into varying line-shape designs. To allow the operator more freedom in

variability, thermoplastics can be molded and remolded on-site while heated at glass transition temperature.

Materials: Thermoplastic Characteristics

Understanding thermoplastics is critical to being able to predict how the sheets will deform. Below is a review of important concepts

involved with accurately predicting deformation.[6]

Glass Transition Temperature – A glassy state is reached when, in the polymer specimen, long chains are entwined and tangled in a

liquid-like manner without rapid molecular motions (typical of a liquid).[6] The molecular backbones are crumpled and immobile.

Note, at temperatures between glass transition and melting (see melting below), the polymer consists of rigid crystals and a low

modulus amorphous fraction. The polymer is flexible and tough.


Design Report

The glass transition temperatures are extremely important in modelling the thermoplastic sheet deformations. Temperatures

between the glass transition temperatures and melting temperatures will need to be tested in order to determine the affects the

temperature of the sheet has on the deformation geometry.

Thermal Expansion: As the temperature of the polymer increases, the crumpled and immobile backbones move further

apart, increasing the thermal expansion coefficient.[6] The thermal expansion value is crucial in determining the conductive

temperature flow through the polymer sheet.

Softening Point: The amorphous fraction of a crystalline polymer drops in modulus.

Microstructure – Thermoplastics can be classified as either amorphous, crystalline or partly amorphous (See Figure 4). Amorphous

thermoplastics have no order to the way in which the polymer chains in its molecular structure are ordered.[6] The chains are often

intertwined and random, giving poor mechanical properties when heated above the glass transition temperature. Amorphous

thermoplastics have a tendency to fail due to stress cracks more easily and are often quite brittle. Due to the lack of light scattering

crystalline regions, amorphous thermoplastics are often translucent or transparent.

Crystalline thermoplastics have a molecular structure that appears extremely orderly and structured without the random

entanglement seen in amorphous polymers.[6] Crystalline thermoplastics exhibit higher toughness due to the presence of so many

intermolecular forces. At higher temperatures, crystalline thermoplastics maintain some mechanical properties due to their

structure. In reality, most thermoplastics have regions of both amorphous and crystalline structure and as a result exhibit more

moderate properties.

Figure 4 – Thermoplastic microstructures: Amorphous (left); Crystalline (right).

Melting Temperature – Variation of crystal sizes within a polymer provides a melting range rather than one particular temperature

value.[6] The melting temperature of a polymer is dependent on the length of the molecular segments within a crystal.

Crystallization Rate – When a polymer melt starts to cool, crystallization begins.[6] It is initiated at various nucleation sites

throughout the melt. Crystallization grows from nuclei to spherulites (comprised of many crystals), crystals growing along the

spherulite radius. Therefore, the rate of crystallization is dependent on the rate of nucleation and the rate of crystal growth. To

properly control deformation, understanding how the plastic will behave as it cools is critical.


Design Report

Design Options (Based on the technical review, identify possible design options, discuss benefits / downsides of

each option, provide a rationalized decision for the design option you will pursue? This section should not exceed 2 pages.)


Design Report

Detailed Design (Provide a detailed engineering design: identify appropriate analysis / experimental

techniques, perform analysis / experiments, evaluate/describe detailed design. This section should not exceed 10 pages.)

Modeling

To study and understand the effects of varying different manufacturing parameters a model has been created. Using a

model is much easier than buying materials and physically constructing the manufacturing aparatus to do testing, in

addition an unlimited amount of trials can be completed with no addition cost other than time. Taking the time

contraints of this project into account, the detail involved in the models used for this project have been kept to a

minimum. Instead of trying to perfectly predict the precise deformation of the part in question, the goal of the model is

to investigate the effect of changing parameters such as temperature of the air, distance from the sheet, air pressure,

sheet thickness, air flow profile etc. To get these so called first order results, many assumptions can be made that will

still yield a sufficiently accurate model.

Thermal Modeling

Before being able to mechanically model a deformation based on the prosposed manufacturing process, it is of

paramount importance that the heat transfer and resulting temperature distributions are understood. To achieve this

understanding, a heat transfer model was created using Microsoft Excel, this model was checked against analytical

methods to ensure that it had sufficient accuracy.

To streamline the process of mechanical modeling and to make it much simpler, one of the assumptions that has to be

made is that the process of heating is much faster than the process of deformation. With this assumption in place it can

be assumed that the heating happens completely before deformation and that the temperature is essentially at a steady

state for the entirety of the deformation. After completion of the thermal model it was discovered that this assumption

was a good approximation because the thermoplastic sheet able to be heated to the glass transition temperature within

a second or less and the deformation took about an order of magnitude longer. This approximation allows the

deformation model to work independently of varying temperatures and removes a large amount of coding which allows

the deformation modeling to complete timesteps much more quickly.

THERMAL MODEL SETUP DETAILS

Mechanical Modeling

Mechanical modeling for this project was done using ABAQUS software which is located on a UNIX blade server located

at UBC. The program itself is quite robust and allows for 3D modeling of both heat transfer and mechanical deformation.

For the purposes of this project however, the capabilities of ABAQUS needed are rather minimal and as a result the

usage of the software remaing quite simple. Nevertheless, the process of creating the 2D model in ABAQUS will be

explained briefly as it isn't as ubiquitous as Excel.


Design Report

Model Setup

The first step in building a model is to create the shape of the part over which a mesh can be laid which will contain the

nodes and elements needed for the software to complete finite element analysis. The nodes are the points at which the

values of temperature, elastic modulus, creep coefficient etc. are known and the elements are all the points between

which can have interpolated values. The mesh size for the model was selected as millimeters and the mesh size was

matched in Excel. All nodes at the left and right edges of the mesh were fixed to simulate the frame which might hold a

thermoplastic sheet during heating and deformation. This was achieved using a simple ENCASTRE command in the

software.

To provide ABAQUS with the heat transfer model results, a simple txt file was outputted that matched each node to a

temperature. In addition to the force of gravity, a file was included that represented the gaussian force distribution

resulting from air pressure. This main.f file models the air pressure according to the equation:

P = Patm + Pcompressor * exp(-A*X)

Where Pcompressor can be varied to change the peak value at the center of the nozzle exit and A is the coefficient that

changes the profile concerning decline rate. Along with density, poisson's ratio , elastic modulus and creep coefficient

data provided by Dr. Chad Sinclair, ABAQUS has all it needs to complete the modelling process. Elastic deformation in

the model is simple to implement, only requiring that an elastic designation is given. Power Law Creep deformation

which is the type of deformation which best serves to model the glass transition temperature process of thermoforming

is slightly more difficult to implement. Power Law Creep follows the equation:

E = Aσn * tm

Where A is the creep coefficient which varies with temperature, n is always equal to 1,and m is always equal to m.

Sheet Size

There are no hard constraints on the sheet size given by the customer. There are however some constraints on order of

magnitude arising from the challenges of manufacturing, transport, ease of use etc. For this reason a maximum size of

sheet has been set at approximately 1m. The sheets used in the modeling can however be any size at or below 1m as the

model can be used to represent smaller, local areas which are being heated on a larger sheet.

Thermal Model

Using the Excel thermal model, it is extremely easy to vary the sheet size. The reason for doing so is mainly to investigate

the extent of heating properly. For a sheet which has a size too large, the heating may be limited to only a small local

area. This would lead to poor resolution of the affected area and wouldn't provide the clearest understanding possible.

For a sheet which has a size too small, the heating may occupy the entire sheet. If the entire sheet becomes heated to

the glass transition temperature it means that it will not clearly show the gradient of heating at the edges which is


Design Report

important to know. The best case scenario is that the sheet size is selected such that the entire sheet is heated to some

degree but a transitional area below glass transition temperature is located near the edges of the sheet. This will give

enough resolution to show the heating gradient in its entirety without having wasted space in the model.

Mechanical Model

The process of varying sheet size in the ABAQUS deformation model is quite a bit more involved than in Excel. Each time

a new sheet size is needed, a completely new part has to be created and meshed and the coding for it has to be

modified to fit with the rest of our model. Fortunately, the size of the sheet can more or less be determined by studying

the results of the thermal model. Again much of the issue arises when the size does not match the area that receives

sufficient heating. When the sheet is too large, only a small portion in the middle is plastically deformed and due to

creep while the edges become elastically deformed to a large degree. This is a rather dissappointing result of making a

simple 2D model. In the model, when the center portion of the sheet becomes heated to the glass transition

temperature, each fixed side of the sheet no longer has a mechanical link to the other side. This turns each into a 2D

cantilever of sorts with gravity and air pressure acting as stresses, causing large amount of elatic deformation. In reality

and in 3D, the fixed ends of the sheet would have sub glass transition plastic adjacent to in on both sides which would

act to deter this cantilever behaviour. If the sheet size is too small, the entire sheet is heated to glass transition

temperature and the deformation has less than ideal properties due to lack of a gradient between fixed edges and the

center. Taking these things into account and using the heating data provided by the thermal model, it was decided that

the sheet size to be used would be 100 mm x 100 mm.

Thickness This section seems redundant if we want to remove something

The thickness, like the sheet size was not expressly defined by the customer. In this case however it is quite clear why

the thickness would be above and below certain levels. If the thickness is too low, perhaps below 1mm, the sheet would

have insufficient mechanical properties. It would be easily damaged and would not likely last long. If the thickness was

higher, perhaps above 10mm, the thickness would afford sufficient mechanical properties but the weight and cost

associated with manufacturing and transporting the sheets would likely be prohibitive.

Thermal Model

In terms of affecting the thermal model, the thickness should change the time required to heat the sheet to a sufficient

temperature. The time difference, may or may not however be enough to make a difference since the sheet is only

going to vary between 1-10mm. After consulting the results of the thermal model it was decided that varying the

thickness between 1mm and 10mm did not really cause a significant enough change in time to rule out any thicknesses.

Mechanical Model

In terms of mechanical modeling, varying the thickness would likely change the time required for deformation assuming

the heating reaches the same degree in different thicknesses. Unfortunately, for the scope of this project, testing the

effect of varying thicknesses in the mechanical model seems to be a less practical usage of time than testing other


Design Report

parameters involved with the process. The logical choice for a thickness between 1mm and 10mm would be 3mm as it is

the thickness which was used by the client, Blair, this will produce a directly comparable deliverable at the end of the

project.

Pressure

Thermal Model

The pressure of the air stream will have an effect on the heating rate of the sheet. Increasing the pressure should

increase the rate of heating because in essence there is more air coming into contact with the sheet, bringing more

thermal energy to the heat transfer. The heat transfer model shows that varying the pressure of the air has very little

effect on the rate of heating. This is due to the fact that the heating to glass transition temperature is accomplished so

quickly, it occurs so quickly that any further increase in pressure produces diminishing returns.

Mechanical Model

Varying the pressure of the air stream will also have an effect on the deformation in the mechanical model. The main

loading on the thermoplastic sheet comes from the pressure of the air contacting the sheet, this is supplemented by the

force of gravity. ADD RESULTS

Temperature

Thermal Model

The temperature of the air as it leaves the nozzle of the air compressor can be varied anywhere between just above the

glass transition temperature of polystyrene , 100°C, and just above the melting temperature, 220°C. Changing the

temperature should have an effect on both the time to reach glass transition temperature and the width of the glass

transition zone in the sheet. As discussed previously, the time to reach steady state is quick enough for that to be of

little concern. The width of the glass transition zone however, is extremely important as it will effect the way in which

the sheet deforms.

Mechanical Model

The width of the glass transition zone will affect the width and depth of the produced deformation in the sheet as well

as the rate. ADD RESULTS

Distance from sheet

The distance from the air nozzle to the sheet will affect many properties simultaneously. Firstly, the temperature and

the pressure at the nozzle will decrease as they approach the sheet, increasing the distance will lead to a larger

difference between nozzle temperature and pressure and those at the sheet surface. Secondly, the profile or shape of

the air changes as it moves from the nozzle to the sheet. Infinitely close to the nozzle the air resembles a stream or point


Design Report

force, at an infinitely large distance from the nozzle the shape of the air becomes wide according to a gaussian

distribution. ADD PHOTO

Thermal Model

Varying the distance to the sheet can have similar effects to that of varying the temperature, since the temperature is

also tied to the distance. This time however, there will be a larger variance of the width of the glass transition zone due

to the changing profile of the air stream.

Mechanical Model

Varying the distance to the sheet also has similar effects to that of varying the pressure since the pressure is also tied to

the distance from the sheet. The further the nozzle is from the sheet, the wider and less concentrated the pressure

profile becomes. ADD RESULTS


Design Report

Socio-Economic Assessment of Design (Describe the cost of the design, the environmental

impact of the design or project, the safety considerations. This section should not exceed 3 pages.)

With the design of a new process to thermoform the thermoplastic sheets, more than just the physical problems of the

design will need to be considered and evaluated. If our process is to be marketable and therefor usable by Blair, the cost will need to

be competitive and need to have a clear breakdown of the environmental impact. The environmental impact will focus on the design

properties that would help decrease the impact of the process on the environment. However, given more time, further research into

the effect of using a material other than polystyrene for the sheets would be done. And lastly the safety of the worker needs to be

guaranteed. A process needs to guarantee a worker his safety as long as proper instructions are followed. In this section of the

report, these aspects will be discussed in further detail and a breakdown of each category will be provided.

In this project, the economics of the old process will have to be compared to the economics of the new process. The first difference

in cost will be the difference in energy use during the process itself. The forming in the old process was done by heating the sheets

using heating lamps for set amounts of time. By varying the times, different depths of points and lines could be reached. Blair

provided us with the heating times used by him, and since we can estimate the power of the lamps used by Blair; we can find the

energy consumption to form a predetermined amount of sheets. This was the only energy consumed during the actual forming of

the sheet since the deformation was gravity assisted. In our new process, we have two main energy consumers, the heating nozzle

and the compressor. Using our estimated forming times obtained in the deformation model and the average wattages on these

consumers we can find the total energy consumed during the actual forming process. These results are given in the following table:

#sheets 100Labourprice $20.00 $/h

amountoflamps 2 voltage 120 V

lampwattage 250 W Current 15 Asetuptime 5 min watts 1800 Wformingtime 4 min nozzle wattage 200 Wchangetime 1.5 min formingtime 1.5 min

555 min changetime 1.5 min9.25 hours 300 min

energycomsumption 4.625 kWh 5.0 hoursEnergyrate $0.10 $/kWh energyconsumption 10.00 kWh

EnergyCost $0.47 Energyrate $0.10 $/kWhlaborcost $185.00 EnergyCost $1.01totalcost $185.47 LaborCost $100.00

totalcost $101.01

totalruntime

Compressor

totalruntime


Design Report

When looking at this table it can be concluded that the original process will be lower in energy cost. When comparing the

total cost of energy to the cost of labour, it can be concluded that the cost of energy usage is much smaller than that of labour and

that it has virtually no impact on the final cost of forming the sheets. The cost of labour was taken to be the average hourly wage of

a general construction labourer in the Vancouver area.[13]

Other cost factors are the initial setup cost of the process. Blair’s process was fairly inexpensive to set up since heating

lamps of 250 W can be purchased for approximately 10 dollars. The start up cost for our process lies higher since both the

compressor and heating nozzle need to be bought. The compressor can range anywhere from $250 to $2000 dollars depending on

the quality, pressure output and volume of the compressor. Our process will work with at 1800 W, 4-gallon compressor that can be

bought for $285. For the nozzle, a quote from the manufacturer regarding the exact model that we will need was required. The

manufacturer came back with a price of $400 dollars. As can be seen from these prices, the original process used by Blair would have

a cheaper initial setup cost when it comes to machine setup.

Another advantage of the process developed by us is that the rental of a workshop is not necessary. The process takes place

on site, eliminating the midpoint used by Blair to develop the sheets. The cost to rent a workspace in or around Vancouver seems to

vary between $1500/month to $2000/month. Extra costs for the workshop would include heating, electricity, water and general

labour for clean up and maintenance. Eliminating these costs would make a process much more economical for Blair.

The rental of a workspace ties in to the next important factor in our socio-economic report, the difference in transportation

cost and environmental impact. The transportation of unformed sheets is much easier and more efficient than that of formed

sheets. Our method would allow the process to happen on site, allowing the material to be transported to the worksite as flat sheets

directly from the store or manufacturer. The old process used by Blair required the transportation of flat sheets to a workshop

where the sheets were formed. These sheets would then be moulded to the desired shape and sent off to the work site. These

formed sheets have a depth of up to 10 cm compared to the 3 mm thickness of the flat sheets. In the table below we compare the

efficiency of transporting flat sheets versus formed sheets. It will give us the amount of sheets that can be transported per cubic

meter of space.

When studying the overall life cycle, it is important to note that for both processes, the energy used and CO2 associated

with the production of the flat sheets is the same. This is also the case with the disposal of the formed sheets, therefore the

calculations performed for this section do not account for those aspects of the life cycle process.

The environmental impact is important to take into account when choosing what process is most suitable for this project.

This environmental impact includes everything from energy consumed during forming, to the CO2 emissions created during the

transportation of the products. When looking at the transportation of the products we can see a clear difference in the two

processes. As seen in the previous figure, the energy used to form 100 sheets using the old method is 4.265 kWh, while the energy

consumed in our process is 8.33 kWh. From this comparison we can see that it is much more economically and environmentally

depth 0.003 m depth 0.1 m

width 1 m width 1 m

length 1 m length 1 m

volume 0.003 m^3 volume 0.1 m^3

#sheets/m^3 333 #sheets/m^3 10

flatsheets formedsheets


Design Report

friendly to transport flat sheets compared to pre-formed sheets. These m3 values can be used to determine the size of vehicle or

amount of trips needed to transport the sheets to the worksite.

Safety is a very important factor in the design of any process. Safety to the worker needs to be guaranteed if the proper

instructions are followed. In this section we will set out some basic steps that need to be followed to avoid injury on the jobsite.

Always wear PPE (safety glasses, ear buds, gloves, steel toe boots, long sleeved shirts and pants)

Keep hand away from the front of the heating nozzle.

Never point the nozzle at anything you don’t want to melt.

Place compressor on stable and level surface.

Do not handle formed sheets with bare hands.


Design Report

Recommendations (in one page, summarize your findings and provide recommendations for future work)


Design Report

Project Planning (Describe the project planning process, task breakdown and specifically which student(s)

were responsible for each task. Discuss progress and provide details of challenges experienced in completing the project. Provide a Gantt chart for the project. This section should not exceed 2 pages.)


Design Report

References

[1] Callister, W. D. (2007). Materials Science and Engineering: Introduction (7th ed.). New York, NY: John Wiley & Sons Inc

[2] Cambridge University. CES Software. Cambridge, England.

[3] Creep Rate Equation. DoITPoMS - Cambridge Universty. Cambridge University, 1 Aug. 2006. Web. 13 Oct. 2014.

<http://www.doitpoms.ac.uk/tlplib/creep/rate_equation.php>.

[4] Gaskell, David. An introduction to transport phenomena in materials engineering. Momentum Press, 2012.

[5] Klein, P. W. (2009). Fundamentals of Plastic Thermoforming (7th ed.). Ohio, OH: Morgan and Claypool Publishers.

[6] McGrum, N. G., Buckley, C. P., & Bucknall, C. B. (1997). Principles of Polymer Engineering (2nd ed.). New York, NY: Oxford

Science Publications.

[7] Rosen, S. R. (2012). Thermoforming - Improving Process Performance. Dearborn, MI: Society of Manufacturing Engineers

(SME). Retrieved September 13, 2014, from http://app.knovel.com/ (978-1-61344-956-1).

[8] Throne, J. L. (2011). Understanding Thermoforming (2nd ed.). Munich, Germany: Hanser Publishers. Retrieved September

13, 2014, from http://app.knovel.com/ (978-1-61344-303-3).

[9] Satterfield, B. (2014). VarVac Breaking the Mold. Vancouver, Canada.

[10] "Core77 2014 Design Awards." Core77 2014 Design Awards. N.p., n.d. Web. 13 Oct. 2014.

<http://www.core77designawards.com/2014/recipients/breaking-mold-varvac-wall/>.

[11] "Houminn - Blair Satterfield." Houminn - Blair Satterfield. N.p., n.d. Web. 19 Nov. 2014. <http://www.houminn.com/blair-

satterfield/>.

[12] "Polymer Types." Polymer Types. N.p., n.d. Web. 19 Nov. 2014. <http://www.ami.ac.uk/courses/topics/0210_pt/>.

[13] "British Columbia - Vancouver Zone: Schedule of Wage Rates." Government of Canada, Human Resources and Skills

Development Canada, National Headquarters, Labour Program. Web. 19 Nov. 2014.

<http://www.labour.gc.ca/eng/standards_equity/contracts/schedules/british_columbia/vancouver_zone/schedule.shtml>.

[14] "Business Rates Prices." BC Hydro -. Web. 19 Nov. 2014. <https://www.bchydro.com/accounts-billing/customer-service-

business/business-rates-overview/business-rates-prices.html>.

http://app.knovel.com/

http://app.knovel.com/


Design Report

Appendix A - Figures

Figure 1 – Stippling involves the formation of shapes through points/dots (left); hatching involves the use of lines parallel to each

other (top right); cross-hatching involves the use of hatching in perpendicular directions (bottom right).

Figure 2 – Vacuum forming (top left); Blow molding (top right); Press forming (bottom left); Extrusion molding (bottom right).


Design Report

Figure 3 – Stiffness vs. Temperature for thermoplastics through glass transition temperature range.[6]

Figure 4 – (Temperature vs Relative Molar Mass (log) for thermoplastics.[6]


Design Report

Date post:	14-Aug-2015
Category:	Documents
Upload:	muhammad-harith-mohd-fauzi
View:	120 times
Download:	0 times

FINAL REPORT

Documents