Acetal Copolymer vs Dupont Delrin® Homopolymer: Properties and Benefits of Each
Industrial Plastic Supply, Inc. has been supplying a vast inventory of plastics to a wide customer base since 1975. Today, we put the spotlight on two products that are incredibly similar, but have key differences that result in each performing optimally in certain applications: the Acetal Copolymer and the Delrin® Homopolymer.
Both of these acetal materials are incredibly similar, with similar beneficial properties. They are both compliant with FDA, ITAR, and RoHS standards. Both are very stiff plastics with excellent dimensional stability in average environments. They are self-lubricating, easy to cut with standard tools, and abrasion and wear resistant. The major differences between them however are a result of their differing structures.
What Is Polyoxymethylene
Polyoxymethylene (also known as POM for short) is an important and commonly used engineering plastic material. There are two distinct types of POM; the first is Homopolymer Acetal and is commonly called Dupont Delrin®. The other is Copolymer Acetal and is referred to by the trade names Celcon®, Sustarin® C, Tecaform®, Ultraform®, Kepital® and many others. Both versions of POM are very popular thermoplastic materials. They both are commonly used for parts that need to be stiff, dimensionally stable and have low surface friction.
Delrin® Homopolymer
The homopolymer possesses much more regularity in its structure, with a repeated, crystalline pattern throughout the plastic. As a result of its strong, crystalline makeup, the Delrin® Homopolymer has superior physical properties, such as better fatigue and creep resistance, and bearing properties. Also, it has better short-term heat resistance compared to the acetal copolymer, with a much higher melting point.
However, this homopolymer does experience minor and inherent center-line porosity. This is basically a band area of tiny porous holes along the center of a rod or sheet. Depending on the severity of the porosity, these holes could weaken a finished part or cause other problems with its performance.
Acetal Copolymer
We’ve found that our customers tend to gravitate towards the acetal copolymer when they require a wider processing window, lower costs, and better long-term resistance to heat and alkaline environments. The acetal copolymer is not as crystalline in its structure, which causes it to not only have a generally lower melting point, but when incorporated with other materials, also increases the tolerance for high melting temperatures.
The less crystalline structure of the copolymer means that this plastic isn’t quite as strong. However, its mixed molecular structure has several benefits. The acetal copolymer has improved resistance to oxidation, improved chemical resistance, and much better long-term resistance to heat. That difference in chemical resistance is much more pronounced with exposure to hot water, especially chlorinated water. The acetal copolymer survives much longer than the homopolymer in these conditions.
Final Thoughts
Both the Acetal Copolymer and the Delrin® Homopolymer have their benefits. Depending on your application and requirements, you can choose the best acetal based plastic for your needs. In need of a supplier of plastics and plastic materials? Check out the rest of Industrial Plastic Supply today!
Both Acetal (POM) grades have very similar properties. Our clients seem to prefer the Dupont brand name Homopolymer materials because of the superior physical properties. The issues that lead clients to the Copolymer is a slightly lower cost, and the minor inherent center-line porosity in the Delrin® 150SA Homopolymer grade.
Dupont™ Delrin ® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
The Delrin® 150SA is a brand name of Dupont, and it is often referred to as POM-H or Acetal Homopolymer. Common brand or trade names for extruded Acetal sheet and rod materials include: Tecaform® AH, SUSTARIN® C, ZL® 900-C, Pomalux®, Unital®, Mechatec Acetal®, Acetron® and many more. This excellent mechanical plastic material is also referred to as: Acetal Copolymer rod, Copolymer Acetal rod, Copolymer Plastic Rod, Acetal Copolymer vs Acetal Homopolymer, Homopolymer Acetal rod, Acetal Homopolymer rod, and many others.
Specializing in Wholesale Acetal and Delrin Engineering Plastics, Mechanical Plastics and High Performance Plastics
**Note: Delrin® is a registered Trademark of Dupont
Both the Dupont Delrin® and Acetal Copolymer are FDA Compliant
They are very stiff and have excellent dimensional stability
Are self-lubricating, abrasion-resistant, and have excellent wear properties
Cuts extremely well with standard cutting tools
Delrin® AF (PTFE Filled), Glass Filled and Specialty Grades Available
Delrin® Rod and Plate have similar properties and frequently replace:Noryl®, Nylon and PET materials
Some reasons to choose Homopolymer vs. Copolymer
Both POM grades have very similar properties. Our clients seem to prefer the Acetal over the Homopolymer materials due to the inherent center-line porosity in the Delrin® Homo-polymer version. This means, that along the center of a rod, or the middle of a sheet, there is a band of area with tiny porous holes. This can weaken or cause problems with a finished part, and in extreme cases, you may see blow by or leakage at this center line. While Delrin® is a brand name, it is a POM Homo-polymer.
The most requested and popular item we supply is the Acetal; the POM Copolymer resin made by one of the other big resin manufacturers – like BASF or Celanese/Tacona.
Both Delrin and Acetal are ITAR compliant, and Delrin and Acetal are RoHS compliant.
The most requested and popular item we supply is the Acetal; the POM Co-polymer resin made by one of the other big resin manufacturers – like BASF or Celanese/Tacona.
Both of these premium performance plastic resins are readily available. If you would prefer the Delrin® brand Sheet or Rod, drop us a line, send us an email – we will be happy to ship the requested material for you. We don’t make judgments on the suitability of material for your application, we just supply what you, our clients ask for. Please, just let us know ahead of time if you have a preference. There are a few other names we hear when people are looking for Delrin®, like Delron, Delran, Delrun, Delren, and many more. Just let us know, and we will be happy to supply a high quality Delrin® brand or Copolymer Acetal product.
Industrial Plastic Supply proudly stocks Acetal and Dupont Delrin 150SA from these premium manufacturers:
Ensinger® Plastics for Dupont Delrin 150SA and Tecaform AH Copolymer Acetal
Rochling® Plastics for Dupont Delrin 150SA and Sustarin C Copolymer Acetal
Z/L Plastics® for Dupont Delrin 150SA and ZL® 900 series Copolymer Acetal
And many more ‘American Made’ quality plastic manufacturers.
Both Delrin and Acetal are ITAR compliant, and Delrin and Acetal are RoHS compliant.
Acetal materials are excellent machining materials – a favorite of machinists. Works like a soft brass, and has exceptional dimensional stability. It comes as a stress relieved material, however if you plan to do extensive machining, you may need to stress relieve the parts prior to final pass. Rods are machined well in lathe and mill, sheets are machined or cut in most common machine tools.
Excellent Machining
Low co-efficient of Friction
Very low moisture resistance
The work horse of the mechanical plastics family, it is one of the most popular grades of material we supply. Other brand or trade names: Pomalux®, Acetron®, Ensital®, Unital®, Tecaform®, Ultraform®, Celcon®, BASF®, Hostaform®, Ticona®, and Dupont Delrin®. Occasionally we are asked for the difference between Acetal and HDPE – here is an explanation. Applications – Frequently used in:
Wear and Slide machined parts from Rod and Plate
FDA, NSF, 3-A, and USDA Compliant Machined Parts
Easily machined parts for water / moisture environments
Critical tolerance and dimensionally stable parts
185 degrees F Continuous Temperature Environments
Rod and Rods, Sheet and Sheets for numerous applications
Acetal Sheet and Rod Specifications:
In stock we normally carry one of these resins: BASF Ultraform® H4320, Kepital® F10-02, or Hostaform® M25. Current Certifications and Specifications used for Acetal – Delrin®: FDA, USDA, NSF, ASTM D6778 Superseded or out dated Specifications for Acetal – Delrin®: L-P-392, ASTM D4181
Materials Available As
Delrin® Sheet – Delrin®Plate or Acetal Sheet – Acetal Plate: .062″ – 6.0″ up to 48″ X 120″ in Natural (White) and Black.
Delrin® AF Sheet and Plate: .062″ – 3.0″ thick in 24″ X 48″, brown in color
Delrin® AF Rod: .250″ – 10″ diameter rod in up to 120″ lengths, brown in color
Film: .005″ – .062″ up to 24″ wide in Natural (White) and Black (minimums may apply)
Acetal Rod and Rods: .125″ – 10″ diameter in Natural (White) and Black up to 120″ lengths For Colored Acetal – Delrin Rod® Read Here.
Acetal Rod diameters normally in stock: .125″, .187″, .250″, .312″, .375″, .437″, .500″, .562″, .625″, .750″, .875″, 1.0″, 1.125″, 1.250″, 1.375″, 1.500″, 1.625″, 1.750″, 2.0″, 2.250″, 2.500″, 2.750″, 3.0″, 3.250″, 3.50″, 3.750″, 4.0″, 4.50″, 5.0″ and many more – up to 20.0″ diameter rod is available!
Special Formulations: Conductive, Static Dissipative, PTFE-TFE Filled, Glass Reinforced, Custom Sizes, Formulations, or Colors Occasionally we are asked for the difference between Acetal and HDPE – here is an explanation.
Properties are for evaluation purposes only. This information is not to be construed as a warranty, guarantee or assurance that you may achieve the same results. Materials made from different resin types, manufacturing techniques and manufacturers will react differently. The information should be used to compare against other materials only, and each user should make his own tests to determine suitability. No warranty as to this materials suitability are either expressed nor implied.
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:
General Property
ASTM Test
Typical Value Unfilled Homo-Polymer
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
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.
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
**Note: Delrin® is a registered Trademark of Dupont
