Homopolymer Acetal (or Delrin) is one of the more versatile and popular plastics for job shops to machine. Acetal has great physical properties, is easy on tooling and both Homopolymer Delrin and Copolymer Acetal can be found in stock at any reputable plastics distributor.
Delrin AF is an enhanced version of Acetal that can help Delrin AF parts out perform and survive in very demanding applications that unfilled Acetal would not do well in. Despite having a relatively high cost when compared to unfilled Acetal, it is widely used and specified. What is Delrin AF and are all Delrin AF stock shapes the same?
First of all, let's clarify that there are two types of Delrin AF: Delrin AF (full strength) and Delrin AF Blend. Delrin AF is a UL listed product made by DuPont comprised of a 20% PTFE fiber reinforced Homopolymer Acetal (for more information see What are the ingredients in plastics?). Delrin AF Blend is a 13% PTFE fiber reinforced Homopolymer Acetal. The blend is made by taking full strength Delrin AF and "blending" it down with Homopolymer Delrin (150) material. This is done for a variety of reasons but a primary motivator is to reduce the cost by reducing the amount of PTFE in the product. In the molding world it is common to see a Delrin AF or Delrin AF Blend. In the stock shapes world, Delrin AF Blend is the more readily available standard. A great deal of confusion occurs when a print was originally designed to be molded and then gets converted to a machined part instead. Delrin AF blend (13% Teflon) will have a slightly higher tensile strength, modulus, and impact since there is less filler in the material. Delrin 100AF (full strength) would have better wear since it has higher levels of Teflon. Delrin AF is also UL Listed where as Delrin AF Blend is made of UL Listed components but not necessary listed on its own as a stock shape product.
Now there is another product that lives in this same category but is a hybrid of sorts. Tecaform AD HPV13 is manufactured exclusively by Ensinger Inc and is a proprietary blend of Homopolymer Acetal with a 13% PTFE powder reinforcement. This product can offer similar properties and performance but still falls short of Delrin AF and Delrin AF blend. HPV-13 uses a resin that is not UL Listed but it does carry FDA approval so the primary benefit is that it can be used in food grade applications.
So for applications that require FDA approval in an enhanced Acetal material, HPV-13 is the only product for the job. Be sure to check out the physical property comparison sheets on our website to see how they compare and make sure the HPV-13 is tough enough for your food grade application. We are also ready to help with any questions or concerns you may have.