Author Question: A thermoformed part has a total surface area of 1000 cm2 and a required thickness of 1 mm. It is ... (Read 33 times)

oliviahorn72 · **on:** Aug 19, 2018

A thermoformed part has a total surface area of 1000 cm2 and a required thickness of 1 mm. It is formed from a blank sheet with a total usable surface are of 500 cm2 (not counting the part of the sheet used for clamping) and a thickness of 2 mm. When forming the part, the walls often tear. What might be the problem? Explain

What will be an ideal response?

Question 2

What is the major advantage of a flash type mold closure system in compression molding? What are the disadvantages?

What will be an ideal response?

Question 3

Describe defects that will occur if the press used for molding does not have sufficient clamping pressure.

What will be an ideal response?

rekilledagain · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

The material has a 1:2 ratio, but the material is still stretched too far.

Answer to Question 2

The flash type mold closure is the simplest of the three mold types and the least expensive to build. The flash type closure works best for shallow parts and parts where dimensional control and property are not critical. The disadvantages:

There will always be flash requiring post processing and increasing cost. There is always some excess that is used; therefore there is always some waste and it cannot be reground and used again.

Answer to Question 3

Some examples of defects from insufficient pressure include: external blisters, internal blisters, poor gloss, oversized vertical dimensions, and warpage.