Here is another popular question asked by our clients. Is HDPE the same as Acetal / Delrin?
No, they are two totally different materials. Although the natural color of both is a milky white to opaque white, and they do look a bit similar, they are not. (HDPE is milky white to almost translucent depending on thickness, and Acetal is a more opaque white to slightly milky – once again depending on thickness . See picture below of .500″ thick samples of HDPE and Acetal sheets)
The HDPE is a softer material, and is commonly known for its FDA certification and used in numerous food applications, such as: one gallon milk jugs, cutting boards, colored water glasses/cups, and many, many more. While it can be machined, because it is a bit softer and lighter, the tolerances it can be machined to are not very tight. It is not bondable, so it makes a great non-stick surface for sticky foods and adhesives.
The Acetal / Delrin also have FDA certification, and are used heavily in the food processing industry. This material is a more mechanical material and is used in bearing and wear applications, cams, feeder screws, etc. This material is can be machined to tight tolerances, and will wear for long periods without lubrication. Due to its exceptional wear properties, it is not bondable, thus requiring mechanical fastening or threads to assemble. It has a very low water absorption, and you will find it in your toilet tank as the white moving parts in the filler mechanism. It is an extremely popular material for machinists, as it works much like soft brass.
While both materials are FDA approved, are machinable and can be used to make rigid wear resistant parts, they are two different resins and have drastically different physical properties. Another major difference is in the weight of these items, HDPE weighs about 35% less than the Acetal material. Please check the data sheets for more information to assist in proper material selection. Acetal Data Sheet HDPE Data Sheet
Acetal is commonly known as: Delrin, Ensital, Unital, Pomalux, Ultraform and many more.
HDPE is known as: Ultraethylux, Densetec, Polystone G, Fortiflex, Versadur, Hostalen, and many more.
Contact us for more details on the HDPE and Acetal families of plastic materials, e-mail us or call 866-832-9315
Hey there IPS Team, I appreciate the effort to share the differences between materials that look so similar. I use a fair amount of the HDPE, and have bought some Delrin by accident in the past. Interesting stuff.
Thanks for all the help.
Is it possible to vaccumform or Thermoform the Acetal?
Acetal and HDPE are both thermoplastics. While technically you can heat form the Acetal, it is not an easy material to form.
Thick cross sections will take a long time to heat all the way through and the possibility of over heating and releasing formaldehyde gas is elevated. Thin sheet and film can be heat formed with care, but other materials are probably a better choice. Please call for additional information on this or other products. 866-832-9315