Acetal Copolymer vs Delrin® Acetal Homopolymer

It’s more than acetal – it’s Delrin®.

Unlike acetal copolymers, Delrin® is a tough, lightweight and durable acetal polymer with inherent low friction, low wear, low noise, low moisture pick-up and excellent spring back properties. It's so well known that the brand name Delrin® is often misused as the industry term for acetal resin. But, not all acetals are equal!

How is Delrin® different?

The uniform, larger crystalline block structure of Delrin® provides better internal bonding
The uniform, larger crystalline block structure of Delrin® provides better internal bonding

Delrin® is an acetal homopolymer and has a uniform backbone with a larger crystalline block structure than acetal copolymers providing better chemical bonding. As a result, Delrin®  is the stiffest and strongest unreinforced technical engineering polymer available. 

Delrin® offers major benefits over acetal copolymer

Specifying Delrin® for high-performance, high precision mechanical parts can allow to optimize part design and production:

  • Increased design flexibility
  • Thinner wall sections at same physical part performance
  • Lighter parts 
  • Less material usage
  • Improved mold filling
  • Shorter molding cycle times
  • Upgrading from existing tooling delivers higher performance parts
  • For new part design and upgrading with current molds 
  • Potential for reduction in part production cost (customers quote up to 20%)

Mechanical properties comparison

Delrin® offers the potential for reduced material usage and shorter molding cycle times
Delrin® offers the potential for reduced material usage and shorter molding cycle times

For example, Delrin® 500P, our general purpose resin, significantly outperforms general purpose acetal  copolymer across the entire mechanical spectrum: 


  • 80% higher yield strain
  • 65% higher flow rate
  • over 40% higher impact resistance, particularly at low temperature
  • higher stiffness, yield strength, strain at break and creep resistance
  • >1000% higher flex fatigue resistance


Delrin® Properties Customer Benefits
Higher Yield Stress and Yield Strain
  • Better memory of original shape after deflection
  • Useful for snap-fits/buckles and simplicity in assembly
Higher Modulus
  • Stiffer material allows design of thinner-walled parts leading to more efficient use of resin
Higher Flow Rates with Better Mechanical Properties
  • Better filling of thinner-walled cavities
  • Useful for effectively designing thin-walled parts
Much Higher Notched Charpy Impact Strength, even at Low Temperatures
  • Parts that are more resistant to fracture and capable of absorbing much more energy
  • Useful for gears in motors that change directions or stop abruptly and mechanical/moving components in refrigerated environments
Higher Strain at Break
  • Contributes to overall toughness of part
  • Allows deflection farther past yield point w/o part failure
  • Useful for snap-fits and buckles
Higher Creep Resistance
  • Better maintains overall shape over long exposures to loads
  • Maintains tighter fit in snap-fit applications 
  • Better maintains dimensions in spring-loaded applications
Much Higher Fatigue Resistance
  • More durable in high-cycle applications like continuously running gears

White Paper: Let Delrin® Acetal Homopolymer Optimize Your Next Design

How to Maximize the Property Advantages of Delrin® Acetal Homopolymer Over Acetal Copolymer: A Guide for Design Engineers

Comparison of Delrin® 100P homopolymer vs. high molecular weight standard acetal copolymer.
Comparison of Delrin® 100P homopolymer vs. high molecular weight standard acetal copolymer.

Delrin® acetal homopolymer resin - also called Delrin® POM-H - is one of the most crystalline engineering thermoplastics available. Delrin® is a highly adaptable material that bridges the gap between plastics and metals and offers unique properties. It is specified for high load mechanical applications and precision parts, where strength, stiffness, stability and reliability are important. Applications range from gears, safety restraint components, door system and conveyor systems components to medical delivery devices, ski bindings, zip fasteners and many other applications across a wide range of products and industries.


When compared to acetal copolymers, Delrin® homopolymer combines higher fatigue and creep resistance with overall higher toughness and higher tensile strength and stiffness, allowing for thinner and lighter part design, and the potential for reduced part production cost.

This white paper describes the differences between Delrin® homopolymer and acetal copolymer in detail and explains how to make the best use of the higher level of mechanical performance of Delrin® homopolymer over that of acetal copolymer in order to extract the most value for all stakeholders.

Table of contents

  1. Introduction
  2. What is an acetal polymer
  3. Key properties of Delrin® acetal homopolymer
  4. Mechanical properties comparison in detail
  5. When to use Delrin® acetal homopolymer
  6. Customer benefits of mechanical properties
  7. How to exploit the superior mechanical properties of Delrin® acetal homopolymer vs. acetal copolymer
  8. Case study
  9. How all stakeholders can benefit
  10. Conclusion

Delrin® Acetal Homopolymer Outperforms Acetal Copolymer and Reduces Cost Per Part

Designing for Delrin®, a global customer gained significant cost savings

A major customer used Delrin® acetal homopolymer over acetal copolymer to redesign the next generation of their part. The result: thinner, lighter part design at same part performance that allowed the company to shorten production cycle time and to gain significant cost savings in part production cost.  

The Challenge

The customer was considering acetal copolymer for the next generation of their part, as the company was offered acetal copolymer at a discount to the price of Delrin®.

The Solution 

Original Design in Acetal Copolymer
Original Design in Acetal Copolymer

Delrin® technical specialists offered support in part design to demonstrate the increased design flexibility with Delrin® at same part performance, and the potential for significant cost savings by delivering:

  • More strength and stiffness
  • More impact toughness
  • More creep and fatigue resistance
  • Higher flow rates


Delrin® outperforms acetal copolymer in mechanical properties. For the customer, these features translate into the potential for:

  • Increased design flexibility with thinner and lighter parts
  • Faster processing time
  • Both of which can lower cost per part through reduced material consumption and improved productivity of molding machines.

    Design in Delrin® 300TEDesign is disguised for customer confidentiality
    Design in Delrin® 300TE Design is disguised for customer confidentiality

    Optimized Part Design

    In order to optimize the design of the part to fully exploit the superior mechanical properties of Delrin® while maintaining the necessary stiffness for part performance, Delrin®  engineers started with Delrin® 300TE, removed the ribs, reduced the diameter of the center thick section, and reduced wall thickness along the face of the part. 


    The Advantages

    By optimizing the part design for Delrin® the customer saw:

    • 21% weight reduction
    • 11% faster cycle time

    This translated into 12% lower overall cost per part, relative to the copolymer alternative.

    Key Takeaway

    By focusing on design optimization using a resin with superior mechanical properties, a lower cost per part was achieved.