39-245
Rapid Design through Virtual and Physical Prototyping
Carnegie Mellon University
Spring 2003

What Are The Size And Shape Limitations On The Parts?

Limitations of making a part with injection molding comes from any limitations of making a mold. Also, one must consider the nature of melted and reharded plastics. Like many other materials, heating causes expansion, and the following cooling process can cause shrinkage and warping. These can affect the strength and integrity of the final product. There is virtual molding software on the market that helps predict what sorts of warping may occur to a product, these are used in the prevention of such effects.

Some thin parts may break during the removal process. Parts shouldn't have undercuts, eliminating the need to slide the product out of the mold in several directions.

For the most part, the general size of a part is unlimited. Above is an example of a really large metal mold for a plastic injection molding process.

These diagrams can show what sorts of warping may occur and how the warping can be prevented using structural elements.

Lars Hanson - Juliana Lim - Tuan Ly - Mark Rau