Homopolymer Acetal (or DuPont 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 DuPont Homopolymer Delrin® and Copolymer Acetal can be found in stock at any reputable plastics distributor.
DuPont Delrin® AF is an enhanced version of Acetal that can help DuPont 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 DuPont Delrin® AF and are all DuPont Delrin® AF stock shapes the same?
First of all, let's clarify that there are two types of DuPont Delrin® AF: DuPont Delrin® AF (full strength) and DuPont 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?). DuPont Delrin® AF Blend is a 13% PTFE fiber reinforced Homopolymer Acetal. The blend is made by taking full strength DuPont Delrin® AF and "blending" it down with DuPont 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 DuPont Delrin® AF or DuPont Delrin® AF Blend. In the stock shapes world, DuPont 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. DuPont Delrin® AF blend (13% DuPont Teflon®) will have a slightly higher tensile strength, modulus, and impact since there is less filler in the material. DuPont Delrin® 100AF (full strength) would have better wear since it has higher levels of DuPont Teflon®. DuPont Delrin® AF is also UL Listed where as DuPont 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 DuPont Delrin® AF and DuPont 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.