Thermoforming

Question 1

Thermoforming involves heating a plastic sheet and then using a _____________to form it over or into a mold

Answer 1

pressure difference

Question 2

Thermoforming is a relatively new process (since ______) and is often used for__________, but also be used to make durable products.

Answer 2

WWII, packaging

Question 3

Thermoforming offers relatively ______ product-specific investments with a large range of texturing and finishing options and production volumes (from _______to ______________)

Answer 3

low, one-offs hundreds of millions

Question 4

In this Thermoforming method, material is formed over the mold

Answer 4

Positive Forming

Question 5

In this thermoforming method the material is formed into the mold.

Answer 5

Negative Forming

Question 6

In this Thermoforming method, a partial vacuum draws the material to the mold

Answer 6

Vacuum Forming

Question 7

In this Thermoforming method, a higher pressure forces the material to the mold

Answer 7

Pressure Forming

Question 8

In this Thermoforming method, sheets below 2.5 mm thick are exclusively used

Answer 8

Thin-gauge forming

Question 9

In this Thermoforming method, sheets above 2.5 mm thick are used

Answer 9

Heavy-gauge forming

Question 10

Steps of Thermoforming:
1.
2.
3.
4.
5.

Answer 10

Heating the material, Forming, Cooling, De-Molding, Edge trimming

Question 11

In Thermoforming, heating the material and Cooling take up ________% of cycle time

Answer 11

80-90

Question 12

While being heated, the material in Thermoforming is typically
stretched _____________

Answer 12

Biaxially

Question 13

Heating can be done with _____________, ceramic, electric or gas heaters

Answer 13

infrared

Question 14

In Thermoforming, ________ heating is sometimes
applied to heat certain areas of the sheet
more than others

Answer 14

Differential

Question 15

In thermoforming, the hot sheet is _______ on all sides into an airtight box and material is forced around (or into) the mold with a pressure differential. ____________ are then placed in the mold to vent the air beneath the product

Answer 15

clamped, small holes

Question 16

How long does the forming step take?

Answer 16

Fractions of a second

Question 17

Thinner products can be formed _______ than thicker products

Answer 17

Faster

Question 18

When plastics get stretched too fast it is called _________. This restricts how fast the forming process can be done.

Answer 18

Yielding

Question 19

_________ Formed products are thinnest at their edges

Answer 19

Positive

Question 20

_________ Formed products are thickest at their edges

Answer 20

Negative

Question 21

________________can only be done on the side of the
product that makes contact with the mold

Answer 21

Texture/Embossing

Question 22

Multi-cavity molds can only be used with ___________ forming

Answer 22

Negative

Question 23

Cooling time depends on ___________, ___________, ______________

Answer 23

Material type, thickness and initial temperature

Question 24

______________ molds cool products more slowly while _______________ molds can have water cooling to cool products much faster

Answer 24

Wooden, aluminum

Question 25

To ease removal of part, negative ______________ are often added to forces the part out of contact with _______ of the mold by applying force in only one direction

Answer 25

draft angles, all sides

Question 26

____________ is the removal of the material that does not end up in the final product

Answer 26

Edge Trimming

Question 27

For thin-gauge products edge trimming is done by simple ______________ but for heavy-gauge products, edge trimming is often done with a saw or _____________

Answer 27

cutting, CNC router

Question 28

Heating is typically done with electrically powered ________ heaters for thin-gauge sheets and more robust ________ heaters for heavy-gauge sheets

Answer 28

Infrared, ceramic

Question 29

In high volume production, heating is typically done from ______________

Answer 29

Both sides

Question 30

Heating time is roughly proportional to __________________

Answer 30

Sheet thickness squared

Question 31

Cooling time increases with ____________ and can be reduced somewhat by using ____________ pressures and spraying water mist onto the part

Answer 31

thickness, higher

Question 32

In ______________, a sheet of plastic is clamped, heated and blown up into the desired shape (usually a dome) and then cooled in air

Answer 32

Free Blowing

Question 33

In Free blowing, __________ mold is used, so cycle times are ___________ (usually a few minutes) and form-freedom is very limited

Answer 33

No, longer

Question 34

In Standard Thermoforming, a heated plastic sheet is forced _____ or _____ a mold

Answer 34

over, into

Question 35

Standard Thermoforming offers large form freedom, but part wall thickness and its distribution is difficult to control, so molds cannot be too _____ or ______

Answer 35

deep, complex

Question 36

Standard Thermoforming part sizes can span a wide range. Production volumes can range from ________ to _______ and cycle times range from a few _______ to a few _________

Answer 36

one off, millions, second, minutes

Question 37

_________________ is like standard thermoforming except the sheet is first stretched by blowing it ______ from the mold

Answer 37

Pre-Stretch Thermoforming, Away

Question 38

Pre-stretch Thermoforming generates a more ______________ thickness distribution which allows for more complex and ____________ molds, but adds complexity and time to the process

Answer 38

Homogeneous, deeper

Question 39

_______________ Thermoforming is similar to pre-stretch thermoforming, except sheet is blown against a cold plug.

Answer 39

Plug-Assisted

Question 40

In Plug-Assisted forming, the portion of the sheet that contacts the plug stays relatively ____________, while the hotter portions thin out. This gives better control over part thicknesses and is good for products that require _________ thickness tolerances

Answer 40

Thick, tight

Question 41

______________________ Thermoforming is a relatively ______ method where two sheets are heated and formed in their respective molds

Answer 41

Twin-Sheet

Question 42

In Twin-sheet thermoforming, the two parts are pressed together before the material is fully ___________ which allows for the manufacturing of __________ parts

Answer 42

cooled, hollow