Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Thermoforming & Die Cutting
of
Recycled/Virgin PET Sheet
by Larry Koester, Sheila Nemeth, & Mark Koester of Lavergne Group
Contents
Section Page(s)
Introduction 2-3
What is PET sheet? 3-6
Intro: PET in relation to other resins 3-4
PET vs. PVC 4-5
PET Sheet Properties 5-6
Extruding PET Sheet 6
Thermoforming PET Sheet 7-9
Heating PET Sheet 7-8
Forming PET sheet 8
General Do s and Don ts of Thermoforming PET Sheet 9
Die Cutting PET Sheet 10-14
Kiss Cut Dies (Steel Rule and Forged Dies) 10-11
Scissor-type Dies (Matched Metal Dies) 12-13
General Do s and Don ts of Die Cutting PET Sheet 14
Conclusions 14-16
Summary Checklist 15-16
Appendixes 17-27
I. Glossary 17-20
II. Transition Temperatures of Thermoformable Polymers 20
IIIA. 2000 Gross Recycling Rate 20
IIIB. RPET End Use Products 2000 21
IV. Plastic Bottles by Resin Type 21
V. Comparison of Thermal Conductivity and Thermal Diffusivity for Several Polymer 22
and Mold Materials
VI. Shrinkage Values 22
VII. Inflation Pressure Ranges 22
VIII. Drying Conditions 23
IX. Coefficients of Thermal Expansion for Thermoformable Polymers 23
X. Make-Ready Procedure for  Kiss Cut Dies 24
XI. Physical Properties of Film Extruded of PETG and APET 25
XII. Technical Data and Property Comparison: RPET vs. PVC 26
XIII. Rockwell Hardness Scale of Abbreviations 26
XIV. Application Pictures 27
Sources, Thanks and Contact Information 28
Lavergne Group Inc. 8800, 1er Croissant, Ville d Anjou, Quebec, Canada H1J 1C8
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
~ Introduction ~
Over the years, a steady increase in the use of PET has triggered a decrease in the use
of aluminum, glass, and other conventional packaging materials. Convenience stores are now
stocked with chilled rows of PET bottles of soda, water, milk, and juice, and finding a glass
bottle has become a rarity. Even beer bottles have seen a recent shift to plastic at sporting
events. The upward trend and usage of PET bottles has trickled down to increased use of PET
in other applications including thermoformed PET sheet. Local groceries and hardware stores
are a gallery to the multiple uses of PET sheet from fruit containers to plastic trays to nut and
bolt packages. With this perspective in mind, it is crucial to evaluate the current uses,
techniques, properties, and characteristics in thermoforming and die cutting recycled and virgin
PET sheet.
When a polymer is heated from a low temperature, it transforms from a glassy state to a
rubbery state. The temperature in which this transition occurs is generally termed  glass
transition temperature (abbreviated Tg), and the temperature range over which the polymer is
sufficiently pliable for stretching and shaping to a desirable shape is called  thermoforming
window. Thermoforming is the general category of processes heating a polymer sheet to this
rubbery state and then using one of several methods to shape the heated sheet into the desired
form. After cooling and hardening, the edges are cut away through a procedure called die
cutting leaving the completed product. While the process may seem simple, numerous factors
dictate and manipulate the slim degree of perfection needed to create a perfect product. Not
only must the physical properties of the cooled substance be considered, but the properties of
the polymer when it is heated must also be calculated.
Polyethylene terephthalate or more commonly PET is a polymer made by combining
either terephthalic acid or dimethyl terephthalate acid with ethylene glycol. From this
chemical combination, a vast range of thermoplastic applications and uses arise for PET and its
additive offshoots. PET is an extremely versatile substance, because its properties and
characteristics provide relatively easy usability and versatility. Virgin PET sheet s compliance
with Food and Drug Administration (FDA) regulations has allowed a diversity of food
applications including such packaging staples as clamshells, trays, containers, and fruit and
vegetable baskets. And recycled PET (RPET) through regrind and addition with virgin has
allowed companies to create their needed product along with allaying many environmental
concerns of tomorrow.
The industry has coined several acronyms to specify PET s specific end use
capabilities. For example, when used in the crystalline state for ovenable trays, PET is referred
to as CPET; when used as oriented film to utilize its toughness, high-temperature and chemical
resistance properties, it is termed OPET; when used for the extrusion blow-molding of
containers, it is called EPET; and when glycol modifiers are added to minimize brittleness and
premature aging, it is called PETG. The acronym APET describes PET when it is in the form
of clear, amorphous sheet for thermoformed packaging and related products. And RPET
signifies recycled PET sheet, which displays similar properties as virgin PET or APET. PETE
is utilized on the bottoms of bottles because of copyright infringement of  PET Carnation
Milk products. For all intense and purposes, APET, PET, RPET, Polyester and PETE are the
same thing, polyethylene terephthalate.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Thermoforming is heating the sheet, to a temperature below its melting point, to a
glassy or soft state, and then stretching it to contours of a mold. The characteristics of PET
sheet are similar to other amorphous sheet, and thus the thermoforming methods are
comparable as well, especially with PVC. The key considerations to remember with PET sheet
are to keep it very dry and to not overheat; otherwise significant changes occur in the PET
weakening its properties. PET is a tough substance, which leads to the biggest challenge
facing thermoformers: die cutting. Although other substances break after only cutting part way
through, PET sheet has to be cut completely through for it to fracture. This puts a tremendous
strain on equipment and laborers. The two techniques for die cutting are clamp cut or kiss cut,
which includes steel rule and forged die, and scissor type, which includes matched-metal
cutting. This will provide the basics to cutting, but if a few guidelines are followed, then your
efforts will improve and benefit as well.
~ What is PET sheet? ~
As previously mentioned in the introduction, PET (also known as APET, RPET, PETE
or polyester) is a plastic resin chemically constructed by combining terephthalic acid with
ethylene glycol. Plastics consist of hydrocarbons, basic building blocks typically derived from
natural gas or petroleum. These hydrocarbon monomers are bonded into long chains called
polymers or plastic resins. Different combinations of monomers will result in resins with
specialized characteristics and properties. Much like different metals like copper, silver, and
aluminum displaying unique properties, which result in varying uses, plastics, are very
versatile and display varying properties and characteristics resulting in a wide range of
applications. No single polymer is perfect for every application. Cost as well as an individual
polymer s benefits must be considered.
The resins that constitute nearly all the plastics used in thermoforming (See Appendix
IV for percentage breakdown of top 6 resins used in plastic bottles):
" Polyesters or PET (polyethylene terephthalate) is a clear, tough, stable polymer with
exceptional gas and moisture barrier properties. It is often used to contain carbon
dioxide (alias carbonation) in soft drinks bottles. Its applications also include film,
sheet, fiber, trays, displays, clothing, and wire insulation.
" Acrylic or PMMA (polymethyl methacrylate) is a tough polymer with good optical
clarity, weatherability, and resistance to sunlight, which make it great for outdoor
items like sky domes, signs, light fixtures, and bathtubs.
" PC (polycarbonate) is a tough, high temperature transparent plastic but is difficult to
thermoform and is very susceptible to moisture. It is used in windows, helmets, cases,
and glasses.
" PE (polyethylene) is the most used polymer in thermoforming with an array of
applications. It is a durable, tough, inexpensive plastic with excellent impact, moisture
and chemical resistance.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
" PP (polypropylene) has great high-temperature chemical resistance and is used in
manufacturing industrial parts, automotive and electrical hardware, stadium seats, and
battery cases.
" PS (polystyrene) was the dominating thermoforming material 20 years ago. It has
excellent processability and good dimensional stability but limited solvent resistance.
Its uses today include food and medical packaging, housewares, toys, furniture,
advertising displays, and refrigerator liners.
- HIPS (high impact polystyrene)
" Vinyl or PVC (polyvinyl chloride) has very similar properties as PET displaying
excellent clarity, puncture resistance, and cling. As a film, vinyl breathes the right
amount making it ideal for packaging fresh meats.
PET vs. PVC
As Table 1 shows, PET displays physical similarities as PVC. The comparable nature
of their density, thermal conductivity, thermal expansion, rigidity, and shrinkage allows for
machines designed and used for thermoforming PVC to be slightly altered in order to
thermoform PET. As Table 1 points out key similarities, Table 2 (on the top of the next page)
shows several key differences. The advantages of PET over PVC is its faster cycle times and
lower oven temperatures, which leads to less energy used and economic savings. PET s
toughness of cutting and wearing out of dies gives PVC a slight advantage. But with their
similar price, PET displays it s environmental edge over PVC with its ease of recycling and
regrinding. PET regrind can easily be used to return to sheet while PVC regrind is much more
difficult and expensive to reuse.
Table 1: Physical Properties of Thermoformable Polymers
Polymer Density Density Thermal Thermal Heat Thermal Thermal
Conductivity Conductivity Capacity Expansion Expansion
[lb/ft3] [kg/m3] [Btu/] Coefficient
[x 10-3 [Btu/lb. [°F or [x10-6 [x10-6
ft.hr.°F kW/ m. °C] cal/g°C] °F-1] °C-1]
Polystyrene 65.5 1050 0.105 0.18 0.54 40 70
ABS 65.5 1050 0.07 0.12 0.4 50 90
Polycarbonate 74.9 1200 0.121 0.207 0.49 40 70
LDPE 57.4 920 0.23 0.39 0.95 140 250
HDPE 59.9 960 0.29 0.50 1.05 110 200
PP Homo. 56.2 900 0.11 0.19 0.83 85 150
Low-density
4.0 64 0.016 0.027 0.5 110 200
PS foam
Rigid PVC 84.2 1350 0.100 0.171 0.365 45 80
PET 85.5 1370 0.138 0.236 0.44 40 70
from Understanding Thermoforming by Throne, pg. 13 Table 2.2
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Table 2: Technical Comparison of PET and PVC
PET Comparison PVC
Faster Cycle Times Slower
Lower (450°F, 230°C) Oven Temps. Higher (600°F, 315°C)
Lower Energy Higher
= Rigidity =
= Shrinkage =
= Molds =
Stronger Steel for Cutting Not needed to be as strong
Wears out faster Wear of Die Better wear
More pressure needed Pressure for Cutting Less
= Price =
+ Environmental -
Recyclable Regrind Reuse Difficult to Reuse
PET Sheet Properties
While PET packaging is predominately familiar in its application in carbonated
beverage bottles, under proper conditions, PET slowly crystallizes to give a high-temperature,
semi-crystalline plastic. With certain extrusion machines and equipment, extruded PET can be
cooled quickly enough to prevent substantial crystallization, and the result is clear sheet used in
thermoforming.
The PET properties that make it desirable include:
" Clarity and Sparkle
" Toughness
" Light Weight
" Good Gas Barrier
" Solvent/Corrosion Resistance
" Good Cost/Performance Ratio
" Durable, difficult to break
Roll of PET Sheet
Courtesy of the Lavergne Group
" Durable hinge properties
" Recyclable and Regrindable
While these advantageous qualities do stand out, there are disadvantages and difficulties that
must also be considered.
PET is very moisture-sensitive. In other polymers the moisture emerges as bubbles, but
moisture in PET directly attacks its chemical backbone, breaking it down. This is called
hydrolytic degradation (or intrinsic viscosity breakdown) and tends to result in excessive sag
while heating and hard-to-detect loss in properties. PET flake or resin must be dried to a
 moisture level of 0.005% or less (TRS-106B) before extrusion of sheet or injection molding
of bottles, otherwise there will be a reduction in physical properties including impact strength.
Impact strength is the sheet s ability to withstand puncture. While PET can be properly dried
in several ways, it is worth repeating that PET flake must not be moist before processes
including extrusion and injection molding. PET sheet does not need any special drying prior to
thermoforming, but should not be exposed to rain or water. See Appendix VIII for Dry
Conditions of other polymers.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
PET is tougher than other plastic polymers. This toughness is one of the positive
reasons for the growth of PET sheet applications. In particular PET sheet exhibits outstanding
durable hinge properties making longer life packages like PET egg cartons and nut and bolt
packages possible. Polystyrene (OPS or HIPS) packages are suitable for short life packages
like bakery packages, but do not have the toughness or durable hinge properties for longer life
packages. Even PVC sheet do not have the durable hinge properties of PET sheet. This
toughness of PET sheet allows for very durable, longer-life packages, but also creates more
difficulty for cutting and trimming.
The toughness of PET requires very sharp and often heated dies, yet improper trimming
can occur resulting in fuzz, angel hair, and trim dust. Trim dust sometimes dirties the
remaining trim or scrap and consequently ruins PET sheet reclaim or regrind. In order for
reclaim and regrind to function appropriately, the regrind must be kept clean, free from
contamination, and dry.
This paper focuses on amorphous PET sheet or simply APET, but it is worth noting this
distinction between CPET (crystallized PET) and APET. CPET is allowed during processing
to form very quick crystals. These crystals allow it to withstand higher heats that normal
APET cannot. While this makes thermoforming more difficult, CPET s heat resistance enables
usage in microwaves and ovens.
A special characteristic of APET is ease in recycling. Recycled PET or RPET, which
comes from reground trim or scrap of APET as well as recycling of PET beverage bottles,
enables prolonged use without sapping resources or increasing waste. Recycled material is
often combined with virgin PET when it is re-extruded creating a stable, usable blend. RPET s
only real restriction is usage in food packaging, but it is still highly usable in other industrial
packaging applications displaying very similar properties as virgin APET sheet.
Extruding PET Sheet
In extrusion as opposed to thermoforming, raw PET must
be heated past its glass transition temperature of 70 °C (158°F) to
above its melting temperature of 255°C (490°F). At this
temperature this PET is in a liquid state where extrusion
continues. (For a basic comparison of transition temperatures of
thermoformable polymers, see Appendix II.)
PET Sheet Extruder
The extrusion basic process is as follows:
Courtesy of the Lavergne Group
1. PET pellets or flake are dried in a desiccant dryer, fed
into a hopper, and placed on top of the barrel.
2. The barrel of the extruder contains a rotating screw,
which conveys, melts, and pumps the melted resin into a
flat sheet.
3. Calender rolls adjust the sheet thickness.
4. The extruded PET sheet is wound into a clear roll or
stock and cut to the appropriate width.
PET Sheet Extruder
This finish sheet can be used in various thermoform operations to
Courtesy of the Lavergne Group
create the desired product.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
~ Thermoforming PET sheet ~
After examining and comparing PET s various properties and characteristics against
other plastics, it is apparent that, for all practical purposes, PET sheet s viscoelastic properties
are similar to other amorphous polymers such as PVC (polyvinyl chloride) and HIPS (high
impact polystyrene). And consequently, most thermoforming equipment can be adapted to
properly handle PET sheet. There are only slight changes needed in the thermoforming
conditions of PET as opposed to PVC or HIPS.
Basically, thermoforming uses heat, vacuum, pressure, and/or mechanical means to
force the plastic sheet against contours of a mold (or molds). The PET sheet is heated to a
temperature above the glass transition but far below the melting temperature where it softens. It
is stretched over the shape of its mold. Once cooled and removed from the mold, secondary
actions occur on the plastic like trimming, labeling, printing, and cutting.
Heating PET Sheet
When thermoforming PET sheet and most thermoformed polymers, one of the most
important considerations is heating. Heating contributes a significant percentage to the final
cost of a formed product. Under-heating will result in failing to forming to the contours of the
mold. Overheating leads to numerous problems including poor quality and weak end products.
Overheating will crystallize the PET sheet and result in excessive sag and visible haze. This
increases brittleness and hinders thermoformability. With thicker sheet and its longer heating
cycles, crystallinity and haze become greater concerns. Once crystalline haze appears, it can
only be eliminated by re-extrusion of that material. Simply, it is crucial to maintain the PET s
proper forming temperatures (300°F or 149°C).
Table 4: Normal Forming Temperatures
Temperature
Polymer
°F °C
Polystyrene [GPPS] 300 149
ABS 330 166
Rigid PVC 280 138
PMMA [Acrylic] 350 177
Polycarbonate [PC] 375 191
HDPE 295 146
Polypropylene 310 154
40% GR PP 400 204
APET 300 149
from Understanding Thermoforming by Throne, pg. 73 Table 5.8
There are three basic methods of heating sheet: conduction, conventions, and radiation.
Conduction is heat transfer via direct contact between the sheet and the heated area. No matter
what method of actual heating is used, conduction is the primary way energy moves through
the plastic sheet. The speed and heat needed to transfer heat from the surface to the entire
sheet is a controlling factor especially in thicker sheet. Convection is heat transfer by contact
between a fluid medium and a solid. For example, the cooler sheet will meet warmer air, and
an energy and heat exchange will warm the sheet. Faster and more efficient transfer also
occurs in moving air compared to still or stagnant air. Radiation is heat transfer via an
interchange of electromagnetic energy between cold and hot surfaces.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Conduction is much more energy effective than convection heating, but PET s
tendency to adhere to hot metal requires Teflon-coated heating plates. Often, hybrid methods
with combination of each are employed. No matter which heating method used, it is critical to
maintain a uniform temperature across the sheet. Air currents and sudden shifts in surrounding
temperatures should be kept to a minimum. A temperature sensing device will also vastly
improve results when thermoforming.
Along with temperature, time should also be considered when heating.  To prevent
excessive sag and possible crystallization of the sheet, the heating cycle should be as short as
possible, provided the proper sheet temperature is reached. (TRS-111). Time to heat the sheet
will control the machine-cycle and also dictate overall time needed to thermoform. One benefit
of PET over PVC is its faster cycle time, but it should still be noted the importance of
consistency with thermoforming. Each and every cycle should have the same time and
temperatures.
Forming PET Sheet
One of the main advantages of thermoforming PET sheet is its versatility along with its
toughness, durable hinge properties, and reasonable cost. There are numerous options for
thermoforming; one could use plug assist or drape forming; one could use vacuum or pressure
forming; one could use matched mold; the options and adaptations are numerous. This paper
will not go into specific procedures and techniques for thermoforming, but provide only some
general considerations when working with PET sheet.
If one wants information on specifics of thermoforming procedures, see Eastman s
TRS-194A (available by request from Eastman) or  Thermoforming in a Nutshell by Empire
West Inc. s Thermoforming Tech Academy (available at www.empirewest.com/academy/)
The following chart will provide a good starting point for forming sheet, particularly if the
sheet thickness is 1,250 microns (50 mils) or less:
Eastar PETG 6763 APET
Mold Temperature, °C (°F) 40-60 (100-140) 25-50 (80-120)
Sheet Temperature, °C (°F) 140-150 (280-300) 140-165 (280-330)
Plug Temperature, °C (°F) 120-135 (250-275) 125-155 (260-310)
Cycle, seconds 3-10 2.5-6
Forming Pressure, MPa (psi) 0.21-0.28 (30-40) 0.10-0.28 (15-40)
Vacuum, mm (in.) of Mercury 508-660 (20-26) 508-660 (20-26)
The following criteria should also be noted (from Eastman s TRS-111, pg. 15):
1. Mold temperatures below 27żC (80żF) may cause  freezing of the sheet, non-uniform
drawing, and stressed parts; however, mold temperature is the key to faster cycles.
Above 60żC (140żF), a longer production cycle could be required, and distortion of the
part may occur.
2. At temperatures slightly above the Tg of 80żC (176żF), PET can be oriented, but it takes
forming forces much greater than those available in vacuum forming to do so. As the
APET sheet temperature approaches 149żC (300żF), its viscosity is reduced to the point
where it is very formable by pressure and vacuum forces. It should be emphasized
again that stressed and brittle parts can result from sheet that is too cold.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
General Do s and Don ts of Thermoforming PET Sheet (from DDS-3C)
To achieve controlled, consistent, and reliable results when thermoforming PET sheet, a few
basic guidelines should be considered:
Do
1. Use moderate heat settings on thermoforming equipment to give a sheet temperature
between 140żC to 165żC (280żF to 325żF).
2. Use mold temperatures that range from 40żC to 60żC (100żF to 140żF).
3. Monitor temperatures
4. Use shorter forming cycles and lower temperatures than those used in thermoforming
other sheet such as PVC.
5. Use silicone-coated sheet for optimum denesting of blisters.
Don t
1. Overheat sheet. Crystallization will occur if sheet is overheated, resulting in whitening
and embrittlement of the sheet. Excessive sag with resultant webbing can also occur.
2. Use cold molds. Mold temperatures as low as 20żC to 25żC (70żF to 80żF) can cause
 freezing of the film and non-uniform drawing, especially with male molds.
3. Use sheet temperatures below 140żC (280żF). Due to freezing internal stresses in the
part, cold forming can cause embrittlement.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
~ Die Cutting ~
As a recent study by Moskla and
Barr so appropriate stated,  thermoplastic
sheet such as oriented polystyrene (OPS)
and polyvinyl chloride (PVC) are
generally easy to cut, producing minimal
wear on the die and few defects on the cut
edge of the plastic, but  amorphous
polyethylene terephthalate (APET)& is
notoriously difficult to cut. Although
PVC or HIPS break or facture after being
cut only  approximately 75 percent
through the thickness (TRS-1111B 16),
Cutting performance of PET (circles), PETG (squares) an OPS
PET sheet must be cut completely through in (triangles). Solid symbols are for the sheet. Open symbols for
the baseline. (from Moskla-Barr Study)
order to separate cleanly. This puts a
tremendous strain on cutting materials, time,
and laborers.
While there are several ways to cut thermoformed PET sheet, this paper will cover only
the three major ones: steel rule, matched-metal, and forged dies. The steel rule die and forged
die have the same principle of cutting which is a  clamp cut or  kiss cut , where as the
matched-metal die cutting principle is more of a  scissor type cutting action.
I.  Kiss Cut Dies (Steel Rule and Forged Dies)
Most of the concepts and principles in steel rule dies apply
to forged dies.
Steel rule dies offer the least expensive option for limited
volume cutting. This method of cutting is simply a sharpened,
metal cutting edge or knife mounted on a laminated birch or maple
Steel Rule Die
die board. Steel rule dies can function as cut-in-place, and cut-in-
line trimming, but often is best used cut-in-place because that way the PET sheet is still warm
and easing wear on the cutting surface. (For Stanley Rosen s make-ready procedure for
accurately and effectively setting up steel rule dies, see Appendix X.) For cutting simple
designs with a steel rule die, use a long central bevel or a double bevel die with a hardness of
50-55 Rockwell C, especially if the sheet is thicker than 0.25 mm (0.010 in.). Although harder
dies wear better, softer dies of 45-50 Rockwell C may have to be used to prevent breakage
during die fabrication when complex shapes and sharp bends are used. (For information on
meanings of Rockwell Hardness scale, see Appendix XIII.)
Forged die can be used instead of a steel rule die in a cut-in-place trimming procedure,
or also known as a  contact heat pressure forming and cutting procedure. The forged die
method is excellent for middle of the road volume applications, and has an advantage in cutting
PET sheet, because the forged die is cutting hot PET sheet. In a forged die, the PET sheet is
heated and thermoformed by vacuum or pressure forming to the contours of the mold. While
the thermoformed part is still in the mold, the heated forged die is pressed down further
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
through the PET sheet. The die edge makes  kiss cut contact on the base plate cutting the hot
PET sheet.
Kiss Cut Die Diagram
An important factor to consider is the
material s shrinkage from forming to the time
it gets to cutting. Although it would be best to
measure shrinkage from an actual cavity,
 0.005 mm per mm (.005 in per in.) (TRS-
111) or 0.3-0.6 percent is a good rule of
thumb to use with PET sheet. (For
comparison of shrinkage values of other
thermoformable polymers, see Appendix VI.)
Dies should be installed in a press that
has enough force so that it can close smoothly
as and cut completely through the sheet. As
the cut progresses, the press should be capable
of consistently bringing the die to the same
line on the backing plate. Eastman s rule of
thumb for clamp requirements is 70 kg. per
lineal cm (400 lbs. per lineal in.) of rule die.
Pressing too hard will bend the cutting edge
removing its edge and only pressing with its
bent side. Pressing too softly will fail to cut
the part at all.
The preferred material for the backing
plate is stainless steel. Aluminum is not
recommended for backing plates because it
tends to have a short life and often splinters
contaminating parts. No matter what material
is used, the backing plate should have a
hardness less than that of the die. That way
the backing plate will take the wear and the
die will dull less. (There is disagreement on
this point.)
Cutting hot PET sheet is easier than
cutting cold PET sheet. Heating the PET
sheet by applying heat to the die and/or the
backing plate will improve cutting, but
temperatures should not exceed the Tg of the PET sheet or 71°C (160°F). One method of
heating the PET sheet only at the cutting area can be termed  Heat Assisted Die Cutting. The
first step of this die cutting method involves the die touching the PET sheet with low pressure,
so that the sheet contacts the base plate and heat transfers from the base plate to the PET sheet
cutting area via conduction.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
The base plate temperature should be controlled just below the point where the PET
sheet sticks to the base plate (PET sheet at 71żC (160żF)). The base plate should be insulated
in order to maintain temperature and to prevent heat loss. Only the spot where the die touches
the sheet is heated. The rest of the PET part is not distorted. After a short time delay and heat
transfer, the PET sheet in contact with the die becomes softer. The hot PET sheet has reduced
shear strength, which requires less cutting force. The final step is high pressure cutting, which
finishes with  kiss cut contact.
Since the dies must evenly contact the backing plate during cutting to insure the PET is
cutting, one must accurately  make-ready the die to the backing plate to avoid damaging the
die as well as properly cutting the PET. This  make-ready procedure is critical to correctly
cutting PET sheet and not damaging the dies. See Appendix X. for Stanley Rosen s Make-
Ready Procedure for  Kiss Cut Dies.
It may seem obvious, but it is worth reiterating: Cut in the same place every time and
keep dies as sharp as possible to insure the best and most reliable cutting.
II. Scissor-type Dies (Matched Metal Dies)
Matched Metal Die
diagrams from
Thermoforming:
Improving Process
Performance by
Stanley R. Rosen,
copyright 2002
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
II. Scissor-type Dies (Matched Metal Dies)
Matched Metal Die Diagram
A Matched Metal Die, also called a
punch and die, is recommended for large
volume applications. This in-line trimming
method is mounted in a separate cutting press
through which the continuously formed sheet
passes.
The basic concept and functionality of
the matched metal die works with hardness or
more specifically the contrasting hardness. A
harder punch is used with a softer die (typical
hardness is 43 Rockwell C for the die and 55
for the punch). Minimum die clearance must
be maintained, and as it wears, the die can be
peened (A process used on a die to recover
minimum clearance by spreading the edge of
the die back to its original size. Peening is
done with an air-operated hammer. Any
excessive spreading is sheared off by the
punch on the first cycle.) to recover the proper
#1
clearance.
An alternative to contrasting hardness
is equal hardness for both the die and punch
(at roughly 62 Rockwell C). Minimum
clearance is maintained by resurfacing the die
and punch, which takes more time due to
resurfacing of both. There is less downtime
with only one tool, the die, to fix.
Coining may be used in order to #2
extend die life. Coining is a process that
occurs during thermoforming whereby the
areas to be cut are thinned by as much as 50%
by ridges located on the pressure box.
Coining occurs as the pressure box is clamped
to the mold. Coining seals the cavity, locks
the sheet in place, reduces cutting tonnage,
and extends cutter life. Shrinkage of the
formed part must be considered when locating
the area to be coined so that it will properly
#3
match the cutting die.
With matched metal dies, the key concept to remember is maintaining minimum
clearance; otherwise, a clean and efficient cut will not occur.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
General Do s and Don ts of Die Cutting (from DDS-3C)
To achieve controlled, consistent, and reliable results when die cutting PET sheet, a few basic
guidelines should be considered:
Do
1. Use properly guarded roller-die, matched-die, slitters, or guillotine cutters for
maximum tool life.
2. Use sharp and well-maintained cutters.
3.  Make Ready Procedure is critical
4. Make sure that proper clearance is maintained between punch and die when matched-
die cutters are used.
5. Cut completely through the sheet to cleanly separate the parts.
6. Use a stainless surface with a hardness less than that of the die for the backing plate
when using steel-rule dies. (There is disagreement on this point.)
Don t
1. Trim formed blisters if the temperature of the sheet is above 71żC (160żF).
2. Attempt to trim formed blisters unless the equipment and die perimeter are such that
the available cutting force is at least 400 pounds per linear inch.
~ Conclusions ~
While this paper presents numerous aspects, considerations, and suggestions for
thermoforming and die cutting PET sheet, the true functionality of any idea or thought is
results. This paper is intended as merely a stepping-stone into greater consideration of PET as
an option when thermoforming. PET has definite advantages including toughness, hinge-
ability, ease of recycling, and environmentally. PET also has challenges including difficulty
cutting and increased wear of dies resulting from its generally advantageous toughness. Its
clarity and sparkle make it great for applications in packaging from clamshells to nut and bolt
containers. The possibility for applications is vast. See Appendix XV  Application Pictures
to explore the current offerings in PET.
No guide, paper, book, or suggestion provides the exact solution to any problem. As
any engineer knows, a perfect plan may not create a functional solution. Trial-and-error is a
must when thermoforming and die cutting any polymer especially PET and recycled PET, but
if the few suggestion is this paper are followed then experimentation will quickly provide the
desired results.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
The following should provide a general overview when thermoforming PET sheet:
Summary Checklist for Thermoforming and Die Cutting PET Sheet
" Keep PET sheet dry.
" Don t assume that APET sheet will process that same as PETG sheet.
" Use suggested sheet-forming temperatures of 140żC to 165żC (280żF to 325żF).
" Do not overheat the PET sheet, which will cause crystallinity and brittleness in the PET
sheet. (If the PET sheet turns white and crystallizes, then it is overheated.)
" Maintain uniform and consistent sheet temperature
" Choice of PET sheet dies:
o Steel rule dies are the least expensive, and are for small volume applications
o Forged dies are best for middle of the road volume applications
o  Kiss cut contact for steel rule and forged dies is required for PET sheet
o Match-mold dies are the most expensive, are the surest with regard to cutting,
and are preferred for fast, high volume applications
" The recommended cutting force for PET sheet is at least 400 pounds per linear inch of
 kiss cut die. The force required on the corners of the part are probably 2X the linear
sections. These cutting force requirements can be reduced if the PET sheet is hot.
" Hot PET sheet is easier for cutting than cold PET sheet.
o Control the base plate temperature just below the point where the PET sheet
sticks to the base plate (PET sheet at 71żC (160żF)). Insulate the base plate in
order to maintain temperature and to prevent heat loss.
o Steel rule dies are the most difficult to maintain heat, and forged dies are the
easiest to maintain heat. (Some people feel that die temperature are not that
important.)
" Heat Assisted Die Cutting: Low Pressure / Time Delay / Heat Transfer / High Pressure
o The first step of die cutting involves the die touching the PET sheet with low
pressure, so that the sheet contacts the base plate and heat transfers from the
base plate to the PET sheet via conduction.
o The base plate temperature is just below the PET sticking point, and only the
spot where the die touches the sheet is heated. The rest of the PET part is not
distorted.
o After a short time delay and heat transfer, the PET sheet in contact with the die
becomes softer. The hot PET sheet has reduced shear strength, which requires
less cutting force.
o The final step is high pressure cutting, which finishes with  kiss cut contact.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Summary Checklist for Thermoforming and Die Cutting PET Sheet (cont.)
" Precision of the cutting tools and dies is critical for proper cutting of PET sheet
o HIPS, OPS, and PVC sheet will fracture or break when the die is 50-70%
through the sheet; (Some of the PVC sheet is hard and the sheet will fracture.
Some of the PVC sheet is soft and the sheet will distort, which will cause the
thermoformed part to break easily from the sheet.)
o The  kiss cut die must be 90-100% of the way through the PET sheet before
the thermoformed part is separated from the PET sheet;
o With matched metal dies, the key concept to remember is maintaining tolerance;
otherwise, a clean and efficient cut will not occur.
" No matter what material is used, the backing plate should have hardness less than that
of the die. That way the backing plate will take the wear and the die will dull less.
(There is disagreement on this point.)
"  Make Ready Procedure is critical for proper  kiss cutting of PET sheet
o A flat base plate, which is parallel to the die is critical. If the base plate is worn
out and cannot be repaired, then the base plate must be replaced.
o Doing the proper  make ready procedure takes time and patience. (This job
should be assigned to the person with the most patience in the work force.)
o If the die cutting edge contacts the base metal too much, then the die edge will
mushroom. The die edge will not be able to cut the PET sheet cleanly, and will
create angel hair and fines.
o See Appendix X. for Stanley Rosen s Make-Ready Procedure for  Kiss Cut
Dies.
This paper is part of a research and marketing project by the Lavergne Group. For more
information about PET Sheet, its PET sheet extruding line, thermoforming and die cutting PET
sheet or about the company and its writers, please contact us:
Lavergne Group
PETCO Division
8800, 1er Croissant
Ville d Anjou
(Quebec) Canada H1J 1C8
www.lavergne.ca
To contact any of the presenters or writers of this paper:
Larry Koester, VP Marketing & Sales, tel. [phone],
fax [phone], [e-mail]
Sheila Nemeth, Marketing & Sales, tel. [phone] ext. 116,
fax [phone], [e-mail]
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix I. Glossary of Terms
Acrylic Polymethyl methacrylate. It is a tough polymer with good optical clarity, weatherability, and
resistance to sunlight, which make it great for outdoor items like sky domes, signs, light fixtures,
and bathtubs. Also known as PMMA.
Amorphous Refers to the physical arrangement of PET molecules. In amorphous PET, the molecules have
had no interaction with each other, and remain independent and randomly oriented. The term
 amorphous implies that no crystalline structures have developed and that end uses will be
limited to temperatures reasonably below the Tg. All polymers are essentially amorphous when
molten. Clarity is a characteristic of amorphous polymers.
Angel Hair Fine fibers caused by improper trimming technique
APET Acronym that refers to an end use of PET that utilizes its amorphous state. Thermoforming is a
prime example. Also known as PET, PETE, or Polyester.
Backing Plate The mild or stainless plate against which steel rule dies cut out the APET sheet.
Bearers Spacers placed outside the sheet area to ensure that press platens do not over-close on steel rule
dies during cutting. Two to four long bears are used, usually 12 mm (½ in.) wide by the height
of the die.
CPET Acronym that refers to an end use of PET that utilizes its unoriented crystalline state. Dual
ovenable trays are an example of this end use.
Coining A process that occurs during thermoforming whereby the areas to be cut are thinned by as much
as 50% by ridges located on the pressure box. Coining occurs as the pressure box is clamped to
the mold. Coining seals the cavity, locks the sheet in place, reduces cutting tonnage, and extends
cutter life. Shrinkage of the formed part must be considered when locating the area to be coined
so that it will properly match the cutting die.
Conduction Heat transfer via direct contact between the sheet and the heated area. It is also the primary way
energy moves through the plastic sheet
Convention Heat transfer by contact between a fluid medium and a solid. For example, the cooler sheet will
meet warmer air, and an energy and heat exchange will warm the sheet.
Co-polyester Polyester modified with additional component(s) to achieve specific properties.
Copolymer A polymer modified with additional component(s) to achieve specific properties.
Crystalline Refers to the physical arrangement of molecules in a crystallizable polymer. Molecules align
themselves into dense, highly ordered crystals when subjected to either a thermal treatment
above their Tg or to an orientation process. The percent crystallinity can range from 0% up to
approximately 50%, depending on the thermal and mechanical history of that sample. A
polymer that is 50% crystalline, for example, will be made up of 50% crystals by weight, all
uniformity dispersed throughout the remaining 50%, which is still amorphous.
Crystallizable Refers to any polymer capable of being crystallized with a thermal or mechanical treatment.
Crystallization Half- The time required for a sample of PET to crystallize to 50% of the maximum crystallinity that
Time could occur at a given temperature.
Denest Lugs Shapes thermoformed into a part that controls the depth to which parts will nest
Drape Forming Thermoforming in which a male mold is pushed into a hot plastic sheet or the plastic sheet is
pulled over the male mold. It is similar to straight forming except that after the PET sheet is
framed and heated, it is mechanically stretched, and a pressure differential is then applied to
form the sheet over the male mold.
EPET Acronym that refers to the use of PET in the extrusion blow-molding process.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Glass Transition The temperature at which APET sheet transitions from a glassy state to a rubbery state. As the
Temperature (Tg) temperature of APET sheet rises from room temperature, an abrupt softening occurs as the
temperature passes through the Tg. During cooling, the formed APET part will return to its
glassy state as it cools below the Tg.
HDPE High density polyethylene. It is used in milk, juice, and water containers. Its chemical
resistance properties also suit it for use in containers for household chemicals and detergents.
Heat Setting A process wherein oriented PET is subjected to an additional heat treatment to increase percent
crystallinity.
Heavy-gauge Commonly, a sheet with thickness greater than 120 mils (03120 in. or 3 mm)
HIPS High impact polystyrene plastic.
I.V. Intrinsic viscosity is a number obtained from a solution viscosity test that represents the average
molecular weight of PET. The value is calculated by extrapolating the concentration of PET in
solution back to zero. The industry commonly uses I.V. as a specification.
In-line Trimming In thin gauge, roll-fed forming, trimming that takes place in a separate machine after the
thermoforming machine.
In-machine Trimming that takes place while the formed sheet is still within the thermoforming machine
Trimming
In-place Trimming Trimming that takes place while the formed sheet is still on the mold surface.
LDPE Low density polyethylene. It offers clarity and flexibility, and is used to make bottles that
require flexibility. To take advantage of its strength and toughness in film form, it is used to
produce grocery bags and garbage bags, shrink and stretch film, and coating for milk containers.
Make-Ready The process of setting up a steel rule die cutting operation. The prime objective of this process is
to obtain clean cutting without incurring damage to the rule dies.
Matched-Mold Thermoforming technique in which the heated sheet is trapped between the male and female
Forming dies, and the male form rams the sheet so that it forms appropriately.
OPET Acronym that refers to an end use of PET that utilizes its oriented state. PET fibers and biaxially
oriented film are examples.
Orientation The process of imparting a degree of molecular alignment by stretching at a temperature above
its Tg. If stretching is in the machine direction only, it is considered uniaxial, whereas biaxial
orientation implies stretching in the machine and transverse directions. Orientation of PET
creates internal stress and rapid crystallization that work together to enhance strength properties
and chemical resistance. Crystals generated by orientation (with or without heat setting) are too
small to refract light and will not influence optical properties.
PC Polycarbonate. A tough, high temperature transparent plastic, which is difficult to thermoform
and is very susceptible to moisture, used in windows, helmets, cases, glasses, and compact discs.
PE Polyethylene. The most used polymer in thermoforming with an array of applications. It is a
durable, tough, inexpensive plastic with excellent impact, moisture and chemical resistance. See
also HDPE and LDPE.
Peening A process used on a die to recover zero clearance by spreading the edge of the die back to its
original size. Peening is done with an air-operated hammer. Any excessive spreading is sheared
off by the punch on the first cycle.
PET Polyethylene terephthalate. A polyester homopolymer made by reacting either terephthalic acid
or dimethyl terephthalate with ethylene glycol. It is a clear, tough, stable polymer with
exceptional gas and moisture barrier properties, and often used to contain carbon dioxide (alias
carbonation) in soft drinks bottles. Its applications also include film, fiber, trays, displays,
clothing, and wire insulation. Also known as APET, PETE, or Polyester.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Polyester A polymer made by reacting dibasic acid with glycol. These monomers are polymerized to a
molecular weight suitable for a specific end use. See PET.
Polymer A generic term used to describe any plastic, usually a homopolymer.
PP Polypropylene. It has great high-temperature chemical resistance and is used in manufacturing
industrial parts, automotive and electrical hardware, stadium seats, and battery cases.
Pressure Box A chamber that is clamped to the mold(s) during thermoforming to supply air pressure to the
exposed surface of the forming sheet. This air pressure, added to that from the applied vacuum,
provides faster forming with improved cycles and better definition. Coining ridges can be added
to the pressure box.
PVC Polyvinyl chloride plastic. It has very similar properties as PET displaying excellent clarity,
puncture resistance, and cling. As a film, vinyl can breathe just the right amount, making it ideal
for packaging fresh meats. Also categorized by Vinyl.
PS Polystyrene. It was the dominating thermoforming material 20 years ago. It has excellent
processability and good dimensional stability but limited solvent resistance. Its uses today
include food and medical packaging, housewares, toys, furniture, advertising displays, and
refrigerator liners.
Radiation Heat transfer via an interchange of electromagnetic energy between cold and hot surfaces
Re-crystallization A process whereby the initial crystallization in a polymer is destroyed through melting and then
allowed to reform when the product is held at a temperature above its Tg.
Rockwell C Category on Rockwell Hardness Scale includes steel, hard cast irons, pearlitic malleable iron,
titanium, deep case hardened steel, and other materials. It is harder than B. See also  Rockwell
Hardness Test and Appendix XIII.
Rockwell Hardness A hardness measurement based on the net increase in depth of impression as a load is applied.
Test Hardness numbers have no units and are commonly given in the R, L, M, E and K scales. The
higher the number in each of the scales means the harder the material. Hardness has been
variously defined as resistance to local penetration, scratching, machining, wear or abrasion, and
yielding.
RPET Recycled PET.
Shear Point Cutting Refers to the crowning of a matched metal die so that the punch first contacts the centerline and
proceeds to cut with a shearing action as it enters the die.
Shrinkage Refers to the unit difference in dimension of a thermoformed APET part with respect to the mold
dimension. An APET part will always be smaller than the mold. A typical shrinkage value for
APET is 0.005 mm per mm (.005 in. per in.) of mold dimension.
Snap-Back Refers to the tendency of an APET sheet to try to shrink and remain horizontal, rather than sag,
when being heated during thermoforming. The degree of snap-back depends on the amount of
internal stress imparted to the sheet by nip polishing during extrusion.
Spherulites PET crystals whose major dimension is greater than one half the wavelength of visible light.
They form when an un-oriented, crystallizable polymer is held at a temperature above its Tg.
Spherulites will refract light to create haze from slight to complete opacity depending on
temperature and time of exposure.
Stability PET is very stable with respect to heat and oxygen at processing temperatures. However, it is
hydrolytically unstable and must be thoroughly dried before melting processing.
Thermoforming temperatures are not high enough to effect hydrolytic stability.
Stripping Rubber Foamed, compressible rubber placed adjacent to a steel rule cutting die that expands after cutting
to force the cut APET part off the die.
See Glass Transition Temperature
Tg
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Thermal Diffusivity Ratio of thermal conductivity to the product of density and specific heat. It is important in time-
dependent heat conduction
Thermoplastic Any plastic material that can be repeatedly subjected to a thermal cycling history without
incurring an increase in molecular weight. This is in contrast to a thermosetting material, which
polymerizes with heat and/or catalyst to achieve its final and permanent state.
Thin-gauge Commonly, sheet thickness less than 60 mils (0.060 in. or 1.5 mm)
Trim That portion of the formed sheet that is not part of the final product
Vinyl See PVC.
Appendix II. Transition Temperatures of Thermoformable Polymers
Polymer Glass Transition Melting Heat Distortion Temperature
Temperature Temperature 66 lb/in2 or 0.46 N/mm2
°F °C °F °C °F °C
Polystyrene 200 94 - - 155-204 68-96
PMMA 212 100 - - 165-235 74-113
PMMA/PVC 221 105 - - 177 81
ABS 190 248 88-120 - - 170-235 77-113
Polycarbonate 300 150 - - 280 138
Rigid PVC 170 77 - - 135-180 57-82
LDPE -13 -25 239 115 104-112 40-44
HDPE -166 -100 273 134 175-196 79-91
Cellulose acetate 158,212 70,100 445 230 125-200 52-93
Homopolymer Polypropylene 41 5 334 168 225-250 107-121
Copolymer Polypropylene -4 -20 302-347 150-175 185-220 85-104
PETG 180 82 - - 158 70
PET 158 70 490 255 120 49
from Understanding Thermoforming by Throne, pg. 11 Table 2.1
Appendix IIIA. 2000 Gross Recycling Rate (NAPCOR 2000 Final Report)
Total U.S. Bottles Collected and Sold for Recycling 769 million lbs
÷ = 22.3%
Total U.S. Bottles Available for Recycling 3,445 million
lbs
Total U.S. Bottles
Year Bottles on U.S. Shelves Gross Recycling Rate
Collected (MM lbs.)
1995 775 1,950 39.7%
1996 697 2,198 31.7%
1997 691 2,551 27.1%
1998 745 3,006 24.8%
1999 771 3,250 23.7%
2000 769 3,445 22.3%
http://www.napcor.com/rate00.html
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix IIIB. RPET End Use Products 2000 (NAPCOR 2000 Final Report)
http://www.napcor.com/rate00.html
Appendix IV. Plastic Bottles by Resin Type
from http://www.plasticsresource.com/resource_conservation/plastics_in_perspective/plastics.html
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix V. Comparison of Thermal Conductivity and Thermal Diffusivity
for Several Polymer and Mold Materials
Material Thermal Thermal Thermal Thermal Thermal
Conductivity Conductivity Diffusivity Diffusivity Conductivity
{Btu/ft.hr.°F] [x10-3 kW/m°C] [x10-4 ft2/hr] [x10-4 cm2/s] Relative to
PS
Polystyrene 0.105 0.180 29.7 7.66 1
ABS 0.07 0.12 25 6.45 0.67
Polycarbonate 0.121 0.207 33.0 8.51 1.15
Rigid PVC 0.100 0.171 32.5 8.39 0.95
LDPE 0.23 0.39 46 11.9 2.2
HDPE 0.29 0.50 55 14.2 2.75
PP homopolymer 0.11 0.19 25 6.45 0.67
PET 0.138 0.236 36.8 9.49 1.3
Low density PS foam 0.016 0.027 80 20.6 0.15
Aluminum 72.5 124 18,850 4860 690
Steel 21.3 36.4 3,930 1010 200
Maple 0.073 0.125 104 26.8 0.7
Plaster 0.174 0.298 120 31.0 1.66
Syntactic foam 0.07 0.12 40 10.3 0.67
from Understanding Thermoforming by Throne, pg. 60 Table 5.1
Appendix VI. Shrinkage Values
Polymer Shrinkage Recommended
Range (%) Value (%)
ABS 0.5-0.9 0.7
EVA 0.3-0.8 0.6
FEP fluoropolymer 1.5-4.5 3.0
Polycarbonate 0.5-0.7 0.6
LDPE 1.5-4.5 3.0
HDPE 2.0-4.5 2.5
PMMA 0.2-0.8 0.6
PP 1.0-2.5 2.0
PS 0.5-0.8 0.6
Rigid PVC 0.1-0.5 0.3
K-Resin 0.4-0.8 0.6
APET 0.3-0.6 0.5
CPET 10-18 12
from Understanding Thermoforming by Throne, pg. 116 Table 9.1
Appendix VII. Inflation Pressure Ranges
Polymer Inflation Pressure Inflation Pressure Inflation Temperature Inflation Temperature
Range [lb/in2] Range [kPa] Range [°F] Range [°C]
PS 2-4 14-28 275-300 135-150
ABS 1.5-4 10-28 285-300 140-150
PMMA 7-10 48-70 320-355 160-180
Rigid PVC 1.5-3 10-21 240-285 110-140
Flexible PVC 1-3 7-21 240-285 110-140
PC 6-10 41-70 350-375 170-190
PET 2-4 14-28 275-320 135-160
LDPE 1-3 7-21 255-290 125-145
HDPE 1-3 7-21 265-300 130-150
PP 1-2 7-14 300-330 150-165
from Understanding Thermoforming by Throne, pg. 84 Table 6.1
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix VIII. Drying Conditions
Polymer Typical Drying Temperature Typical Drying Time [hr]
[°F] [°C]
APET 150 65 3-4
CPET 320 160 4
ABS 175 80 2
PBT 320 160 4
PMMA 175 80 3
PC 300 150 4
from Understanding Thermoforming by Throne, pg. 125 Table 10.1
Appendix IX. Coefficients of Thermal Expansion for Thermoformable Polymers
Polymer Range (10-6/żF) Range (10-6/żC)
ABS 60-130 35-70
EVA 80-200 45-110
FEP fluoropolymer 35-70 20-40
Polycarbonate 70 40
LDPE 100-220 55-120
HDPE 60-110 35-60
PMMA 50-90 30-50
PP 80-100 45-55
PS 50-80 30-45
Rigid PVC 70 40
K-Resin 65-70 35-40
APET 65 35
from Understanding Thermoforming by Throne, pg. 73 Table 5.8
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix X. Stanley Rosen, Author: Make-Ready Procedure for  Kiss Cut Dies
Since the dies must contact the backing plate to get complete cut-through, great care must be
taken during make-ready to ensure that the dies are not damaged. The following is an example
of a make-ready procedure for a  kiss cut die in an on-line trim press:
1. Reduce hydraulic press cutting pressure to the minimum level that will allow actuation
of the lower platen.
2. Prepare a heavy Kraft paper sheet to the exact size of the platen and mark the outgoing
edge as  front . Tape the paper facing the front to the face of the base plate, allow the
press and die to close, and strike the paper, leaving a cut impression on what is now the
 master sheet . Usually 75% of the die will either cut or mark the paper. Remove the
master sheet and base plate; use a pencil to complete the cut impression of cavities that
are incomplete.
3. Obtain 0.002-in. thick x 0.250-in. wide (0.05-mm x 6.35-mm) stainless make-ready
shim tapes with adhesive backing from a die-maker supply house. Study the die
impression on the master and apply one layer of shim tape only on the very light or
penciled-in die impressions. Trim the shim tape so it never extends closer than 0.250
in. (6.35 mm) to a neighboring heavy die impression. The objective is to build up the
shim pack so it never disturbs an existing cut section. Avoid installing loose shims.
They may shift and disrupt the process.
4. Place the master sheet on the lower buildup in the same orientation marked  front as
the die. Install the base plate on top of the master sheet and replace the mounting
screws.
5. Tape a clean Kraft paper cut to the exact size of the striker plate on top. Mark it  No. 1
front on the appropriate edge. Die cut the No. 1 sheet and compare the results to the
master sheet under the base plate. If the die impression still is not uniform, add one
thickness of shim to the master sheet on any faint cuts, including those on the top of
earlier shims. When building upon an earlier shim, cut the length shorter by 0.250 in.
(6.35 mm) from each end so the shimming is feathered and not abrupt at its edges.
6. Save sheet No. 1. Then cut sheet No. 2 and continue the process until the die
impression becomes uniform. Save all the trial-cutting Kraft sheets to keep a record of
progress and as a guide to avoid disturbing sections that were previously cutting. If
previously cutting segments stop cutting, remove the last shims placed on the adjoining
segments and start the process anew.
7. When satisfied that make-ready is complete, insert a flat sheet of the same plastic to be
thermoformed and attempt to trim it at low pressure. If it appears to be a uniform
impression, raise the hydraulic pressure until the die cuts through. Lock the hydraulic
pressure regulator at that point and shim-up area of the impression that may not have
cut through. Judgment and experience will indicate when the die impression is uniform
and when additional hydraulic pressure is needed to cut through a plastic sheet without
dulling the die.
Ref. Thermoforming: Improving Process Performance by Stanley R. Rosen, copyright 2002
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix XI: Physical Properties of Film Extruded of PETG and APET (Eastman's Laboratories)
Property Units Test Method PETG APET
(ASTM)
Inherent Viscosity D 3763 0.70 0.74
Thickness of Film Tested
Microns D374 250 250
Mils 10 10
Density, kg/m3 (g/cm3) D 1505 1,270 (1.27) (1.33)
Haze, % D 1003 0.8 0.8
Gloss @ 45° D 2457 108 108
Transparency, % D 1746 85 85
Transmittance, %
Regular (Specular) D 1003 89 89
Total 91 91
Water Vapor Transmission Rate
g/m2 ź 24h F 372 6 6
g/100 in.2 ź 24h 0.4 0.4
Gas Permeability
cm3źmm/m2ź24hźatm
(cm3źmil/100 in. 2ź24hźatm)
CO2 D 1434 49 (125) 28 (70)
O2 D 3985 10 (25) 5.1 (13)
Elmendorf Tear Strength, N (gf)
M.D. D 1922 13.7 (1,400) 9.8 (1,000)
T.D. 16.7 (1,700) 12.7 (1,300)
PPT Tear Strength, N (lb-ft)
M.D. D 2582 93 (21) 102 (23)
T.D. 93 (21) 120 (27)
Tear Propagation Resistance
Split-Tear Method @ 254 mm/min (10 in./min)
M.D., N (lb-ft)
N/mm (lb-ft/in.) D 1938 9.1 (2.1) 15 (3.3)
T.D., N (lb-ft/in.) 36 (205) 58 (330)
N/mm (lb-ft/in.) 9.1 (2.1) 16 (3.6)
36 (205) 63 (360)
Tear Resistance, Trouser @ 200 mm/min speed,
N/mm (lb-ft/in.)
D 882
M.D. 36 (205) 54 (310)
T.D. 36 (205) 59 (340)
Tensile Strength @ Yield, MPa (psi)
M.D. D 882 52 (7,500) 59 (8,500)
T.D. 52(7,500) 57 (8,300)
Tensile Strength@ Break. MPa (psi)
M.D. D 882 59 (8,600) 58 (8,400)
T.D. 55 (8,000) 39 (5,600)
Elongation @ Yield, %
M.D. D 882 4 4
T.D. 4 4
Elongation @ Break, %
M.D. D 882 400 300
T.D. 400 200
Tensile Modulus of Elasticity
Mpa (105 psi)
D 882
M.D. 1,900 (2.8) 2,200 (3.2)
T.D. 1,900 (2.8) 2,200 (3.2)
Dart Impact, 12.7-mm (½-in.) dia. head, 127-mm
(5-in.) dia.clamp, 660-mm (26-in.) drop, g
D 1709A
@ 23°C (73°F) 400 400
@ -18°C (0°F) 500 500
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix XII. Technical Data and Property Comparison: RPET vs. PVC
Material RPET PVC
Gauge, Mils 10 10
Density, g/cm3 1.33 1.35
Haze, % 0.5 1.2
Gloss at 45 deg. (Gardner) 110 93
Transparency, % 85 36
Tensile strength, psi 7,100 7,100
Tensile Modulus of Elasticity, psi 280,000 325,000
Oxygen Transmission Rate 109 174
cc/sq.meter/24 hr/mil
HVTR.g/100 sq.in. /24 hr 0.40 0.19
80 82
Vicat Softening Point (°C)
Blushing No Yes
Dart, Impact, ½ in.
Dart, g@ 26 in. drop
425 415
At 73 °F (23 °C)
300 345
At -20 °F (-29 °C)
145 167
Heat Deflection (°F at 264 psi)
275-400 315-360
Sealing Temperature (°F)
250-300 275-350
Sheet Temperature (°F)
Courtesy of the Lavergne Group
Appendix XIII. Rockwell Hardness Scale of Abbreviations
The ASTM (American Society for Testing & Materials) has standardized a set of scales (ranges) for Rockwell
hardness testing. Each scale is designated by a letter.
" A Cemented carbides, thin steel and shallow case hardened steel
" B Copper alloys, soft steels, aluminum alloys, malleable iron, etc.
" C Steel, hard cast irons, pearlitic malleable iron, titanium, deep case hardened steel and other materials
harder than B 100
" D Thin steel and medium case hardened steel and pearlitic malleable iron
" E Cast iron, aluminum and magnesium alloys, bearing metals
" F Annealed copper alloys, thin soft sheet metals
" G Phosphor bronze, beryllium copper, malleable irons
" H Aluminum, zinc, lead
" K, L, M, P, R, S, V Bearing metals and other very soft or thin materials, including plastics.
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Appendix XIV. Application Pictures
PET Clamshells PET Hinge
PET Packaging
PET Sheet
PET Snap
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Thermoforming & Die Cutting of Recycled/Virgin PET Sheet (PETCO of Lavergne Group)
Sources
" Eastman Publications: DDS-3C, TRS-65L, TRS-106B, TRS- 111B, and TRS-194A.
" Empire West Inc. s  Thermoforming in a Nutshell available at www.empirewest.com
" Thermoforming: A Practical Guide by Adolf Illig, copyright 2001
" Understanding Thermoforming by James L. Throne, copyright 1999
"  Evaluating the Cutting Behavior of Amorphous PET Sheet Using Steel Rule Dies by
Moskala-Barr from ANTEC 2000
" Thermoforming: Improving Process Performance by Stanley R. Rosen, copyright 2002
Special Thanks to:
" G.N. Plastics Ltd.
" Ontario Die Company
" American Tool & Engineering Inc.
" C.R. Clarke & Co.
" Future Mold Corp.
" Sherwood Technologies, Inc., James L. Throne
" Mold Systems Corporation, Stanley R. Rosen
" Selected PETCO customers, who have reviewed this paper.
This paper is part of a research and marketing project by the Lavergne Group. For more
information about PET Sheet, its PET sheet extruding line, thermoforming and die cutting PET
sheet or about the company and its writers, please contact us:
Lavergne Group
PETCO Division
8800, 1er Croissant
Ville d Anjou
(Quebec) Canada H1J 1C8
www.lavergne.ca
To contact any of the presenters or writers of this paper:
Larry Koester, VP Marketing & Sales, tel. [phone],
fax [phone], [e-mail]
Sheila Nemeth, Marketing & Sales, tel. [phone] ext. 116,
fax [phone], [e-mail]
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