Dupont Delrin Wages War Against Acetal for Ultimate Supremacy

(Newswire.net — June 24, 2015) Anaheim, CA —

One of the most common questions asked when someone calls in for Delrin®, do you want the Delrin® brand name, or the generic Acetal? While this question might seem silly, it is actually a very important step in the process of finding the right product for the customer. While Delrin® is a type of Acetal, Acetal is not a type of Delrin®. The Delrin® material is the Dupont brand name for Homopolymer Acetal, also called POM-H.

Dupont Delrin Compared To Acetal Copolymer

Both products are Acetal, but they are not twins. In reality, the DuPont Homopolymer Delrin® and the copolymer Acetal are more like brothers. While they are in the same family and may have some matching characteristics, they are not entirely the same. One may be better in certain situations than the other.

Similar but not the same

Here are some of the similar characteristics both versions of Acetal contain. Both Homopolymer Acetal and Acetal Copolymer are easily machinable. They are both thermoplastics, meaning you can apply heat to form them. A crystalline, rather than amorphous type resin is used to make Acetal. Because of the uniform molecular structure of Acetal, it can be molded or machined into a huge range of different shapes and sizes for use in thousands of applications.

Both types of Acetal are considered to be self-lubricating plastics. Acetal is a perfect choice for parts that would require a material to be rigid, have excellent mechanical strength and have a low coefficient of friction. Both Acetal materials are FDA approved for food contact, NSF approved for drinking water applications, and 3-A (Dairy) and USDA compliant.

The most widely recognized Acetal is the Homopolymer Acetal commonly known as Delrin®. The Delrin® Acetal is produced by Dupont. Dupont Delrin® is almost exclusively the choice for Acetal Homopolymer. A popular Homopolymer Acetal is Dupont Delrin 150SA, which has a higher flexural strength, flexural modulus, Rockwell hardness, on top of its improved mechanical strength.

The second version of Acetal is the Acetal Copolymer material, and is also known as POM-C. Perhaps the best known Acetal Copolymer is BASF’s H2320. Another well known manufacturer of the Acetal Copolymer resins is Ticona and their brand name is Celcon.

What are the differences between Delrin and Acetal

Now let’s look at what makes these two brothers so different. The first difference normally noticed between the Homopolymer and Copolymer, is that the Homopolymer has centerline porosity. What is centerline porosity you ask? Great question and glad you asked. Centerline porosity is what is sounds like, it is a thin layer porous area in the center of the material, or little air bubbles that have been trapped in the material. This happens because of out-gassing during the heating process of making Dupont Delrin® Homopolymer. These tiny air bubbles get trapped in the center of the sheet because they have nowhere to escape to. This is not a problem in most injection molded parts; as injection molded parts generally have only thin cross-sections.

Homopolymer Acetal, the Delrin version, is the top choice over its brother when it comes to; thermal, impact, and chemical and wear resistance. The Homopolymer Acetal also boasts a slightly lower water absorption rate.

Where does the Copolymer Acetal thrive then? The Copolymer Acetal has a lower coefficient of expansion and a slightly lower specific gravity. Also, the Acetal Copolymer is often slightly less expensive. They have very similar physical properties but Copolymer Acetal is less expensive.

Is Porosity A Problem?

Depending on your needs, centerline porosity may or may not be an issue. If you are milling or boring out the center of the rod, Delrin may be the best choice for you. If you are looking for a more homogenous material and you are using the center of the material, the copolymer Acetal may be the choice for you.