Acetal vs. Delrin

Attribute	Acetal	Delrin
Chemical Name	Polyoxymethylene	Polyoxymethylene
Trade Name	Acetal	Delrin
Material Type	Thermoplastic	Thermoplastic
Density	1.41 g/cm³	1.42 g/cm³
Melting Point	165-175°C	175-180°C
Tensile Strength	~70 MPa	~75 MPa
Flexural Strength	~100 MPa	~110 MPa
Impact Strength	2-3 kJ/m²	2-3 kJ/m²
Water Absorption	0.2% (24 hours)	0.2% (24 hours)
Chemical Resistance	Good	Good
Electrical Insulation	Excellent	Excellent

Introduction

Acetal and Delrin are two commonly used engineering thermoplastics that possess similar properties and are often used interchangeably in various applications. While they share many similarities, it is important to understand their unique attributes to determine the most suitable material for a specific project. In this article, we will explore and compare the key characteristics of Acetal and Delrin, shedding light on their similarities and differences.

Chemical Composition

Acetal, also known as polyoxymethylene (POM), and Delrin are both high-performance polymers derived from formaldehyde. They belong to the family of polyacetals and are characterized by their excellent mechanical properties, low friction coefficient, and high dimensional stability. Acetal is a generic term that encompasses various grades of polyoxymethylene, while Delrin is a specific brand name for a type of acetal resin manufactured by DuPont.

Both Acetal and Delrin have a similar chemical structure, consisting of repeating units of -CH2O- linked together. This molecular arrangement contributes to their exceptional strength, rigidity, and resistance to creep. However, Delrin is often considered a superior material due to its enhanced crystallinity, which results in improved mechanical properties and a higher melting point compared to generic Acetal grades.

Mechanical Properties

When it comes to mechanical properties, Acetal and Delrin exhibit remarkable similarities. They both possess high tensile strength, excellent impact resistance, and low moisture absorption. These attributes make them ideal for applications requiring dimensional stability, such as gears, bearings, and precision components. Additionally, both materials offer good resistance to chemicals, solvents, and hydrocarbons, ensuring their suitability for a wide range of industrial environments.

However, Delrin's higher crystallinity provides it with a slight edge in terms of mechanical performance. It offers improved stiffness, hardness, and fatigue resistance compared to generic Acetal grades. This makes Delrin a preferred choice for applications that demand exceptional strength and durability, such as mechanical gears, bushings, and structural components subjected to heavy loads or repetitive stress.

Machinability

One of the key advantages of both Acetal and Delrin is their excellent machinability. These materials can be easily machined into complex shapes with tight tolerances, making them popular choices for CNC machining and other precision manufacturing processes. Their low coefficient of friction and self-lubricating properties reduce the need for additional lubrication, resulting in reduced maintenance requirements and improved operational efficiency.

While both materials are highly machinable, Delrin's superior crystallinity and higher melting point provide it with a slight advantage in terms of chip formation and dimensional stability during machining. This allows for smoother finishes and tighter tolerances, making Delrin a preferred choice for applications that demand exceptional precision and surface quality.

Thermal Properties

Acetal and Delrin exhibit excellent thermal stability, allowing them to withstand a wide range of operating temperatures. Both materials have a relatively high melting point, with Acetal typically melting around 165°C (329°F) and Delrin melting at approximately 175°C (347°F). This makes them suitable for applications that require resistance to heat, such as automotive components, electrical connectors, and consumer goods.

However, Delrin's higher crystallinity and superior thermal conductivity give it a slight advantage in terms of thermal properties. It exhibits better resistance to thermal deformation and can dissipate heat more efficiently than generic Acetal grades. This makes Delrin a preferred choice for applications that involve prolonged exposure to elevated temperatures or require enhanced thermal stability.

Cost and Availability

When considering the cost and availability of Acetal and Delrin, it is important to note that Delrin is a specific brand name for a type of acetal resin manufactured by DuPont. As a result, Delrin is often priced slightly higher than generic Acetal grades. However, the price difference may vary depending on the specific grade, quantity, and supplier.

Both Acetal and Delrin are widely available in various forms, including sheets, rods, and custom-machined components. They can be easily sourced from numerous suppliers and distributors worldwide. The availability of different grades and sizes ensures that engineers and manufacturers can find the most suitable material for their specific application, regardless of whether they choose Acetal or Delrin.

Conclusion

Acetal and Delrin are two highly versatile engineering thermoplastics that offer exceptional mechanical properties, chemical resistance, and machinability. While they share many similarities, Delrin's enhanced crystallinity and superior thermal properties give it a slight advantage in terms of mechanical performance and thermal stability. However, the choice between Acetal and Delrin ultimately depends on the specific requirements of the application, as well as factors such as cost, availability, and machining precision. By understanding the unique attributes of Acetal and Delrin, engineers and manufacturers can make informed decisions to ensure optimal performance and reliability in their projects.