Author Question: List three considerations that must be taken into account in the placement, number and size of the ... (Read 54 times)

SGallaher96 · **on:** Aug 19, 2018

List three considerations that must be taken into account in the placement, number and size of the vent holes in a female mold used for fundamental (straight) vacuum forming.

What will be an ideal response?

Question 2

Discuss the pressure capabilities of vacuum forming relative to pressure forming.

What will be an ideal response?

ghepp · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

The holes should be as large as possible to allow fast application of the vacuum without showing through onto the surface of the plastic. Soft plastics or those that are heated to high temperatures will probably require smaller holes. The holes should be placed as far apart as is practical while assuring that all areas of the plastic sheet are drawn tightly against the cavity walls. Holes should be placed in any corner or other area where webbing or bridging might be a problem.

Answer to Question 2

With vacuum forming the maximum pressure available is the difference between the pressure in the evacuated chamber and atmospheric pressure. Hence, the pressure is limited to a max of one atmosphere. With pressure forming any pressure can be applied, although normally very high pressures are not needed. The pressures used in pressure forming, however, would always be higher than those used in vacuum forming.