I was sick as could be last week so I did not make any posts. I will resume the normal schedule today.
*Updated with additional information on 8/30/2016
Acetal, also known as poyoxymethylene (POM), is a very commonly used thermoplastic material that we are all familiar with. Everyone in the industry has a story of the time when someone ran some acetal at too high a temperature and had it degrade filling the plant with formaldehyde. However, not everyone is aware that there are actually two different versions of acetal on the market, copolymers and homopolymers.
I see a lot more copolymer being used than homopolymer at injection molders which puzzles me. This might be because the homopolymers tend to come at a premium price. Sometimes, however, you get what you pay for. A brief history of acetal might explain why homopolymer is more expensive and also why you should consider using it
In specifying materials for certain applications, we might need to know what kind of heat resistance that the material has. This is a vague concept at best. What do we mean by heat resistance? Can the heat resistance of a material be altered with additives or fillers?
Let’s delve into a few of these issues and I will show you where to find the best indication of heat resistance of plastic materials as well as give you some guidelines that you can use for picking materials.
When we speak of memory in plastic materials, we are talking about a plastic parts ability to return to its original shape after it is deformed in some way. More specifically, we are talking about a part being able to return to its original shape after being held in a flexed position for an extended period of time.
The question is, what makes a material have good memory and what materials are best used for applications that require this property?
If you want to know why you should not use hydrolysis resistant nylon, read here
Nylon is one of the oldest and most commonly used thermoplastics but there still seems to be a lot of confusion about properly drying nylon and in general about how nylon is affected by moisture. Moisture in the raw material causes many processing issues and part failures and the affects that moisture has on molded parts seems to confound people as well. I hope in this article to clear some of this up.