Delrin: Are You Getting the Real Thing?

Originally Published MDDI April 2002

MEDICAL PLASTICS

In the late 1950s, DuPont developed acetal and trademarked it as Delrin. Acetal's solid performance characteristics make it the most popular machining plastic.

Delrin is a homopolymer. Because of centerline porosity problems, however, a copolymer also called acetal was developed and marketed under other trade names. This copolymer is considered an equivalent of Delrin, though it varies slightly in its mechanical properties.

Delrin was developed first and promoted with a good marketing campaign by DuPont, and the company has been successful in keeping the Delrin trademark alive. According to one estimate by Connecticut Plastics (Wallingford, CT), 80% of component prints specify Delrin over acetal. A copolymer, however, is often a better choice—especially in sheet form.

Interestingly, distributors and manufacturers have teamed up to fix this discrepancy without the engineering world's knowledge. While Delrin is frequently specified, distributors estimate that 80% of the acetals sold today are actually copolymers. Distributors tend to substitute a copolymer without the end-user's knowledge. In fact, the manufacturers now charge more for true Delrin material. If Delrin is needed, it is wise to get certification; otherwise, acetal should be specified on the print.

Copyright ©2002 Medical Device & Diagnostic Industry