Previous research has shown that thermoforming high density polyethylene (HDPE) is something that has been shied away from in the plastics industry. This paper will show the differences of thermoforming HDPE using temperature-controlled and non temperature-controlled tooling. In doing that, it will aim to prove that HDPE can be used with success in the thermoforming industry, as long as temperature controlled aluminum tooling is used.
Individual Performance Objectives
1. Show the importance of temperature-controlled molding in thermoforming.
2. Prove that HDPE can be a relevant material to use in thermoforming, instead of just amorphous materials.
High density polyethylene isn’t usually thought of as a usable material when thermoforming is talked about. It is not a material that seems like it would work with that type of process. Companies in industry have shied away from HDPE, because of its crystallinity and shrinkage rate. The thermoforming industry almost always uses amorphous materials, because they are a lot easier to control than crystalline materials.
Also, a lot of companies use wooden or urethane tooling to run their parts, because it is a lot cheaper to do that than to get aluminum or steel tooling. Instead of heating up their mold with water or oil, and keeping it at a constant temperature, they will just let the heat of the machine and material heat up the mold over time, but will run into problems at the start and end of their runs. The mold will either be too cold for the material and cool it too quickly, or be too hot, which will lengthen cycle time, and increase the chances of part defects.
Increased cycle times and part defects will cost the company a lot of money in the long run, when they could’ve just used a temperature-controlled aluminum mold. A temperature-controlled mold will stabilize mold temperature from the start, and will not have the variation a non temperature-controlled mold will. This will give the company much needed control of the tooling to help give them a chance at producing better quality parts for their customers.