Delrin® Homopolymer Acetal compared with Acetal Copolymer
Many of our clients assume that Delrin® rod and Acetal rod are the same thing. This is not true.
Yes, all Dupont Delrin® rod is Homopolymer Acetal rod, but not all Acetal rod is Delrin® rod.
Delrin® is the trade name for Homopolymer Acetal made by Dupont. Dupont™ Delrin ® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
This is the most recognized of all trade names for Acetal materials, but not the only available Acetal material. The Copolymer Acetal resin 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, Hostaform® M25 and many others.
While Delrin® Homopolymer Acetal is a wonderful material, in a larger cross sections Homopolymer can exhibit center line porosity, or ‘soft centers’. 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 center’s of homopolymer rod and sheet.
This should not stop you from considering Delrin® Homopolymer Acetal though. Many other properties of the homopolymer resins are superior to the copolymer resins. These properties are:
Typical Value Unfilled Homo-Polymer
Typical Value Unfilled Co-Polymer
Tensile Strength Yield
9,600 – 11,000
9,000 – 10,200
Izod Impact – Notched
Hardness – Rockwell
Deflection Temp @ 264psi
Deflection Temp @ 66 psi
Water Absorption @ 24 hrs
Co. Thermal Expansion
Some key properties for homopolymer acetal 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. Extruded Delrin® brand homopolymer resin material also comes in several resin variations, including: Delrin® 150 and Delrin® 507, contact us for details. Dupont™ Delrin® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
Many of our clients prefer the homopolymer rod and sheet for small machined parts. This is due to the increase in a few key properties, and of course brand recognition. Some of our major brand names for quality Copolymer Acetal (POM-C) sheet and Rod include: Tecaform AH®, Sustarin C®, ZL 900® and Pomalux®.
Both resins meet the standard ASTM-D-6778, and the cancelled specs, L-P-395 and ASTM-D-4181. Contact us for certification and specifications you may require.
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 – Homopolymer Acetal Rod, and sometimes referred to as plastic dowel. We also have the capacity to supply colored Acetal Copolymer or Delrin® Homopolymer Acetal rod; click here from more details on the colored Acetal material.
Similar materials to Acetal Copolymer – Homopolymer Acetal are Nylon Rod, PET Rod and Noryl® Rod. Most materials are available as round rod, square rod, bar, strip, sheet and plate.
Are Acetal Copolymer and Homopolymer Acetal the same?
This is one of our most common questions, and it is a bit involved of an answer.
There are two main versions of Acetal Resin
Homopolymer Acetal and Copolymer Acetal
The most popular name for a Homopolymer Acetal is the Dupont Delrin, which is a premium Homopolymer Acetal.
The second Acetal is a Copolymer acetal, and there are many suppliers of this resin.
Acetal is the generic, and not all Acetal is Delrin® Hompolymer, nor is it Acetal Copolymer. A distinction is required to determine which is best for your application. There are several manufacturers that produce Acetal Copolymer resin, including: Celanese®, BASF®, Ticona®, SABIC® and many more.
Acetal Copolymer compared to Delrin® Homopolymer Acetal
Delrin® is a premium homopolymer Acetal produced by Dupont. Many of the physical properties of the homopolymer exceed that of the copolymer Acetal. Dupont™ Delrin® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
The generic term ‘Acetal’ covers both the homopolymer from Dupont and the copolymer 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). Homopolymer Acetal is POM111, and Copolymer Acetal is POM211.
Both are very tough and machinable, and have some similar properties.
An additional difference is the inherit problem of center-line porosity in some of the homopolymer 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 some problems with machining or moisture permeation through the material. The copolymer resin has little to no 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 Copolymer or Homopolymer Acetal.
See Homopolymer and Copolymer Acetal properties chart below.
Tensile Modulus of Elasticity
Flexural Modulus of Elasticity
Heat Deflection Temp @ 264 psi – degrees F
Melting Point – degrees F
Coef. of Linear Thermal Expansion
6.8 x 10-5
5.4 x 10-5
Water Absorption @ Saturation
Material is available as both Acetal Copolymer or Acetal Homopolymer in Rod, Block, Sheet and Slabs.
Acetal is one of the most widely available plastics, especially on the West Coast (for some reason the East Coast seems to 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® Homopolymer and Acetal Copolymer page for additional information on the product availability and data sheets. We get calls for the premium Delrin® Homopolymer product, but some people may call it Delron, Delran, Delrun, Derlin and many other names, but it is still premium Delrin® Homopolymer Acetal to us.