Delrin vs. UHMW

Attribute	Delrin	UHMW
Material	Acetal resin	Ultra-high-molecular-weight polyethylene
Density	1.41 g/cm3	0.93 g/cm3
Tensile Strength	63 MPa	25 MPa
Impact Strength	7 kJ/m2	100 kJ/m2
Temperature Resistance	Up to 100°C	Up to 90°C

Introduction

Delrin and UHMW are two popular engineering plastics that are widely used in various industries for their unique properties. Both materials have their own set of advantages and disadvantages, making them suitable for different applications. In this article, we will compare the attributes of Delrin and UHMW to help you understand which material is best suited for your specific needs.

Chemical Composition

Delrin, also known as polyoxymethylene (POM), is a high-performance acetal resin that is known for its excellent dimensional stability and low moisture absorption. It is a semi-crystalline thermoplastic that offers high strength, stiffness, and toughness. On the other hand, UHMW (ultra-high molecular weight polyethylene) is a type of polyethylene with a molecular weight range of 3.1 to 6 million. It is known for its exceptional wear resistance, low coefficient of friction, and high impact strength.

Mechanical Properties

When it comes to mechanical properties, Delrin is known for its high tensile strength, stiffness, and fatigue resistance. It has a high resistance to creep and excellent dimensional stability, making it ideal for applications that require precision and durability. On the other hand, UHMW has a lower tensile strength compared to Delrin, but it offers superior impact strength and abrasion resistance. It is also self-lubricating, which reduces friction and wear in moving parts.

Thermal Properties

Delrin has a higher melting point compared to UHMW, making it more suitable for high-temperature applications. It has a continuous use temperature of up to 185°F (85°C) and a melting point of around 347°F (175°C). UHMW, on the other hand, has a lower melting point of around 275°F (135°C) and a continuous use temperature of up to 200°F (93°C). However, UHMW has a lower coefficient of thermal expansion compared to Delrin, making it more dimensionally stable over a wide temperature range.

Chemical Resistance

Delrin has good resistance to a wide range of chemicals, including solvents, fuels, and oils. It is also resistant to moisture and humidity, making it suitable for outdoor applications. UHMW, on the other hand, has excellent chemical resistance to acids, bases, and organic solvents. It is also resistant to moisture and UV radiation, making it ideal for applications that require exposure to harsh environments.

Machinability

Delrin is known for its excellent machinability, allowing for tight tolerances and smooth surface finishes. It can be easily machined using conventional metalworking tools, such as milling machines and lathes. On the other hand, UHMW is more difficult to machine due to its low thermal conductivity and high coefficient of thermal expansion. Specialized tools and techniques are required to achieve the desired results when machining UHMW.

Cost

When it comes to cost, Delrin is generally more expensive than UHMW due to its higher performance and machinability. However, the cost difference may vary depending on the specific grade and application requirements. It is important to consider the overall performance and longevity of the material when comparing the cost of Delrin and UHMW for a particular application.

Conclusion

In conclusion, Delrin and UHMW are both versatile engineering plastics that offer unique properties for a wide range of applications. Delrin is known for its high strength, stiffness, and dimensional stability, while UHMW offers superior wear resistance, low friction, and impact strength. The choice between Delrin and UHMW will depend on the specific requirements of your application, such as mechanical properties, thermal stability, chemical resistance, machinability, and cost. It is important to carefully evaluate these factors to determine which material is best suited for your needs.