Is HDPE Sheet and Acetal Sheet (Delrin) the same?

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)

HDPE and Acetal – Some DifferencesHDPE sheet and Acetal sheet Natural Color Samples Both .500" thick sheet

The HDPE sheet and rod 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 HDPE Sheet and Acetal Sheet look similar, they perform quite a bit differently.

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 sheet and rod material weighs about 35% less than the Acetal sheet and rod material. Please check the data sheets for more information to assist in proper material selection. Acetal Data Sheet and HDPE Sheet Data

Acetal is commonly known as: Delrin, Ensital, Unital, Pomalux, Ultraform and many more.

HDPE is also 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
Topic: HDPE sheet and Delrin Sheet (Acetal Sheet)

Acetal Versus Delrin

Is Delrin® the same as Acetal?

This is one of our most common questions, and is a bit difficult to answer.

All Delrin® is Acetal (PolyOxyMethylene or POM).

Acetal is the generic, and not all Acetal is Delrin®. Several manufacturers produce Acetal resin, including: Celanese®, BASF®, Ticona®, SABIC® and many more.

Copolymer versus Homopolymer AcetalAcetal vs Delrin®

Delrin® is a homo-polymer Acetal produced by Dupont. The generic Acetal covers both the homo-polymer Delrin® and the co-polymer grades of resin. Both materials meet the ASTM-D-4181, ASTM-D-6100 or ASTM-D-6778 specification (an old call out is L-P-392). Homo-polymer is POM111, and Co-polymer is POM211.

Both are tough and machinable, and have very similar properties.

An additional difference is the inherit problem of center-line porosity in the homo-polymer grades. This is caused by out gassing during manufacturing, and can be found at the center or on the surface of all homo-polymer extrusions. This porosity can cause problems with machining or moisture permeation through the material. The co-polymer resin does not have this porosity issue.

Some of the other differences are in the physical properties of the resin. Review the chart for some of the most popular properties people ask for when looking at Acetal or Delrin.

See Delrin® / Acetal properties chart below.

Properties Homo-Polymer Acetal Co-Polymer Acetal
Tensile Modulus of Elasticity 450,000 400,000
Flexural Modulus of Elasticity 470,000 366,000
Heat Deflection Temp @ 264 psi – degress F 257 220
Melting Point – degress F 347 335
Coef. of Linear Thermal Expansion 6.8 x 10-5 5.4 x 10-5
Water Absorption @ Saturation 0.90 0.80

Material is available as Delrin® Rod, Acetal Rod, Delrin® Block, Acetal Block, Delrin® Sheet, Acetal Sheet, and Slabs. Acetal is one of the most widely available plastics, especially on the West Coast (for some reason the East Coast like the Nylon – Polyamide material more). Most commonly available in Natural (White) or Black, but can be produced in a wide range of colors with minimum orders. This enables material matching your product color or for easy identification of parts.

While these properties are similar, depending on your application, one material may be better suited than the other. Review our Delrin® / Acetal page for additional information on the product availability and data sheets. We get calls for Delrin® product, only people may call it Delron, Delran, Delrun, Derlin and many other names, but it is still Delrin® to us.

Looking for other colors of Acetal – Delrin® Rod?

Contact us today for more information on Acetal – Delrin® or any other plastic material.

Call us at 866-832-9315 or Email Us for more additional details

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