Acetal – Delrin Sheet vs. ABS Sheets and Rods

Acetal-Delrin® (Delrin® is a trade name for Dupont’s Acetal Homopolymer) and ABS (Acrylonitrile-Butadiene-Stryene) have some similar properties but are really very different materials. They similarities are: high impact strength, ease of machining with standard cutting tools and good mechanical properties. They are also both FDA compliant and are both good substitutes for brass. They also have great water absorption resistance and good electrical properties. Both materials are good for some of the same applications but certainly not all. Listed below are some of the major differences.Natural ABS Rod, Rods, Sheets and Sheet

ABS Sheet and Rod Information

 

  • ABS comes as Natural (straw) and Black color in Plate, Slab, Sheets and Rods, and thin sheet (.040″ – .250″) it is available as White or Black with a textured surface one side. It can be cut from 48″ X 96″ sheets into strip, panels or pieces.
  • ABS is formable. ABS is a great thermo-formable material while Acetal is not. Acetal is used more for machined parts such as gears and screws. ABS is great for molding and shaping parts from vacuum to heat forming. Excellent for model building and prototype projects.
  • ABS is easily bondable (similar to PVC). ABS can be bonded or welded to itself. Because Acetal is self lubricating, it is not possible for anything to stick to it unless etching is done – therefor it is not bondable.
  • ABS is a great material for painting and silk screening. While Acetal can not be painted or silk screened unless it has undergone Corona Treating (a flame surface treatment), but if treated will nice paint or screened surface.
  • ABS has better chemical resistance than Acetals or Delrin®. Both are attacked by acids like sulfuric, but ABS has a wider range of resistance to chemicals like aqueous acids, alkaline and alcohol. Acetal will degrade when exposed to such chemicals as chlorine and alkalines.
  • Specialty grades of ABS are available, including: Glass Filled, Static Dissapating, and Fire Retardant Grades (like Royalite – R59)Machined Black ABS Rod Part

ABS Typical Properties Table

General Property ASTM

TestTypical ValueR59 Typical ValueSpecific Gravity D7921.041.18 – 1.25Tensile Strength YieldD6386,5005,000Tensile ModulusD638320290,000Izod Impact – NotchedD2567.07.8Hardness – RockwellD785R105R93Deflection Temp @ 264psiD648192174Deflection Temp @ 66 psiD648208195Co. Thermal ExpansionD6965.3X10-54.6 -5.5X10-5

 

Acetal-Delrin® Sheet and Rod Information

  • Acetal is the better machining plastic, considered the best machining plastic material. Because of its durability and wear resistance, Acetal is an excellent choice for producing a wide variety of parts that require high wear resistance over a wide period of time. When machining to tight and specific tolerances, Acetal is ideal.
  • Acetal has low co-efficient of friction. Due to its self lubricating properties, it is a great material for sliding and wear applications. This material provides years of maintenance free bushings and bearings.Natural Acetal Machined Gears
  • Acetal – Delrin sheet is produced from .062″ – over 6″ thick and sheet sizes of up to 48″ X 120″ as standard. The standard color for Acetal and Delrin is Natural (a deep milky white) and Black. Some colors are available as Medical Grade, and can be obtained in limited sizes. These sheet are available cut to: slabs, blocks, plates, slabs and blocks.
  • Delrin – Acetal (Polyoxymethylene) can be both a homo and a co-polymer. The Dupont brand name is a homo-polymer which is a repeating chain of one atom while the generic Acetal is a co-polymer which is two atoms forming a repeating chain. ABS is only a co-polymer.

Acetal – Delrin Properties Table

General Property ASTM Test Typical Value Unfilled Delrin® 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

ABS and Acetal – Similar, but very different materials

Both of these materials possess excellent qualities and have a wide range of different uses. Acetal is great for machining, while ABS is great for forming and bonding. They both can be used for machined parts and are great choices for food contact and electrical applications. These two materials are both strong and durable plastics, but one might be better than the other for a specific job. When picking the right plastic, it is important to compare plastics and their specific properties to make sure the material won’t fail and that your job will be successful.

Contact us for additional information, call us at 866-832-9315 or contact us here. Consider Industrial Plastic Supply for all your plastic needs, we want to be your go-to plastic supplier.

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3 Responses to “Comparing ABS to Acetal-Delrin Sheets and Rod”

  1. John gotschall

    I am interested to know which of these two materials (abs vs. delrin) is better in the following application: sliding at low speed, 2ft/sec, against an aluminum rail. preservation of the rail is the goal, as a rail costs >$500.00 to replace and the plastic washer costs <$2.00 retail. I am concerned with the plastic picking up abrasives from the environment and carrying those abrasives against the aluminum. immediately adjascent to the rail is a carpeted floor, dirty with sand, dust, etc. This application is in Cessna 172 airplane: pilot and copilot seat rail ('trolley') assembly. The seat frame has wheels for support and oversized plastic washers that carry the sideways skidding loads to keep the wheels on the rails. The FAA has approved either material, but I want those rails to last forever (I know they won't). I could change the washers often as part of the preventative maintenance program. If I could get zero wear of the aluminum rail I'd be happy to change the plastic washers at every inspection. I just want to know which material will wear the aliminum less.

    thanks

    jg

    Reply
    • Plasticman

      John,
      You ask a good question. There are several things to consider; the material wear properties, the source of the abrasives, and the hardness of the plastic you are considering. The Delrin/Acetal is harder than the ABS sheet material, so any abrasive is less likely to embed in the surface. The Delrin/Acetal also has better wear resistance. The ABS is bondable, if that helps with any installation issues.
      If protection of the rails is the most critical, a guard should be used to keep debris from getting between the rail and the washer. Of the 2 materials, I would personally choose the Delrin/Acetal material. Neither are fire rated materials however.
      Let us know if you have further questions.

      Reply

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