A few weeks ago we examined the most popular high-performance thermoplastic resins, UHMW and Acetal [link to Oct 25 blog]. Today we will study UHMW vs. Delrin to see how these thermoplastics stack up against each other. When it comes to a final product, minor differences can have a major impact.
UHMW is a low-cost plastic that can be found in everything from hip replacements to military vehicle armor. Its properties and benefits include:
UHMW has surface and chemical properties that are rare to find in high-performance polymers. It is very resistant to most chemicals, UV radiation, and micro-organisms, but doesn’t have the same creep resistance as Delrin.
This is a question we hear a lot, and the confusion is understandable. While all Delrin is acetal, not all acetal is Delrin. (All Chevys are cars, but not all cars are Chevys.) Acetal is the popular name for the PolyOxyMethylene (POM) family of thermoplastics. Acetal is available in two general types of resins: copolymers and homopolymers. Delrin is the common name for homopolymer acetal.
Delrin has slightly better mechanical properties than copolymer acetal, but often contains a low density center, especially in large cross-sections. It also has slightly less chemical resistance than the copolymer alternative, but is ideal for applications that benefit from Delrin’s additional strength and rigidity, such as small diameter, thin-walled bushings. Delrin is easy to machine, has very low moisture absorption, and provides a nice machined surface finish.
Other benefits of Delrin over copolymer acetal include:
The only downside to Delrin is centerline porosity. A visible centerline is caused by out gassing during manufacturing and can cause problems with machining or moisture permeation through the material. Thus Delrin is not used for most food and medical applications due to the potential for bacteria growth.
With nearly 40 years of experience machining and fabricating plastic, Reading Plastic’s experts can help you choose the right material for your project. If you are debating UHMW vs. Delrin, call us today at 610-926-3245. We will help you source the plastic you need and meet all of your machining and fabrication needs.
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