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)

Dupont Delrin rod and Acetal Rods

Many of our clients assume that Delrin rod and Acetal rod is the same thing. This is not quite true. Yes, all Delrin rod is Acetal rod, but not all Acetal rod is Delrin rod. Delrin is a trade name for Homo-Polymer Acetal made by Dupont. This is the most recognized of all Acetal materials, but far from the only available Acetal material.Black and Natural Acetal - Delrin Rod
The Co-Polymer Acetal is produced by a wide variety of large plastic manufacturers, BASF is probably one of the largest and most well known. Some main resin names are: BASF Ultraform H4320, Kepital F10-02, or Hostaform M25. While Delrin is a wonderful material, in larger cross sections or larger diameters, the Delrin brand Homo-Polymer can exhibit center line porosity. This can sometimes be seen with the naked eye, and is a darker white in a normally milky white natural colored material. This center line porosity can cause problems in some applications. This porosity can cause leakage of fluid if under pressure, or ‘soft centers’ of Delrin Rod and Delrin Sheet.

This should not stop you from considering Delrin though. Many other properties of the Delrin resin are superior to the Co-Polymer resins. These properties are:

General Property ASTM
Typical Value
Unfilled Delrin®

Typical Value
Unfilled Co-Polymer
Specific Gravity D792 1.42 1.40
Tensile Strength Yield D638 9,600 – 11,000 9,000 – 10,200
Tensile Modulus D638 450,000 400,000
Izod Impact – Notched D256 1.2 1.0
Hardness – Rockwell D785 M94 M90
Deflection Temp @ 264psi D648 257 220
Deflection Temp @ 66 psi D648 347 335
Water Absorption @ 24 hrs
% 0.24 0.25
Co. Thermal Expansion D696 6.83X10-5 5.4X10-5

The key properties that Delrin are: higher tensile strength, increased Izod impact, higher deflection temperatures and it is slightly harder. The co-efficient of thermal expansion is a bit higher, and needs to be considered when designing a new part. Delrin brand material also comes in several resin variations, including: Delrin 150 and Delrin 507, contact us for details.

Many of our clients prefer the Delrin brand rod and sheet for small machined parts. This is due to the increase in a few key properties, and of course brand recognition. Both resins meet the standard ASTM-D-6778, and the cancelled specs, L-P-395 and ASTM-D-4181.Colored Acetal - Delrin Rod - Pomalux

The Acetal family of plastic resins are excellent for wear resistance, great mechanical strength, and superior machining properties. It is available in a huge range of sizes and shapes. Click here for more details on Acetal – Delrin Rod, and sometimes referred to as plastic dowel. We also have the capacity to supply colored Acetal – Delrin rod; click here from more details on the colored Acetal material.

Similar materials to Acetal – Delrin are Nylon Rod, PET Rod and Noryl Rod. Most materials are available as round rod, square rod, bar, strip, sheet and plate.

Please contact us for more details on these and other plastic materials. For a comparison chart of plastic materials click here: Plastic Materials Selection Guide