Delrin vs. Nylon

Attribute	Delrin	Nylon
Chemical Name	Polyoxymethylene	Polyamide
Trade Name	Delrin	Nylon
Density	1.41 g/cm³	1.15 g/cm³
Melting Point	175-180°C	210-260°C
Tensile Strength	~63 MPa	~50 MPa
Elongation at Break	25-100%	100-400%
Water Absorption	0.2%	1.5-9.5%
Chemical Resistance	Good	Good
Electrical Insulation	Excellent	Good

Introduction

When it comes to engineering plastics, Delrin and Nylon are two popular choices due to their excellent mechanical properties and versatility. Both materials have unique attributes that make them suitable for various applications. In this article, we will compare the key characteristics of Delrin and Nylon, exploring their strengths and weaknesses.

1. Mechanical Properties

Delrin, also known as polyoxymethylene (POM), is a semi-crystalline thermoplastic with exceptional strength, stiffness, and dimensional stability. It offers high tensile and flexural strength, making it ideal for applications that require load-bearing components. Delrin also exhibits low friction and excellent wear resistance, making it suitable for gears, bushings, and bearings.

Nylon, on the other hand, is a synthetic polymer known for its toughness and impact resistance. It has a high tensile strength and can withstand heavy loads and impacts without breaking. Nylon also has good fatigue resistance, making it suitable for applications that require repetitive stress or dynamic loads. Additionally, Nylon has excellent vibration damping properties, which can be advantageous in certain applications.

2. Chemical Resistance

Delrin has good resistance to many chemicals, including solvents, fuels, and oils. It is less susceptible to chemical attack compared to Nylon, making it a preferred choice in applications where exposure to chemicals is a concern. However, Delrin may not be suitable for prolonged exposure to strong acids or bases.

Nylon, on the other hand, has a higher chemical resistance compared to Delrin. It can withstand exposure to a wide range of chemicals, including acids, bases, and organic solvents. This attribute makes Nylon a popular choice in chemical processing equipment, fuel systems, and other applications where chemical resistance is critical.

3. Moisture Absorption

One of the key differences between Delrin and Nylon is their moisture absorption properties. Delrin has a very low moisture absorption rate, typically less than 0.5%. This attribute makes it highly resistant to moisture-related issues such as dimensional changes, warping, or degradation in performance. Delrin is often preferred in applications where exposure to moisture is a concern, such as marine components or outdoor equipment.

Nylon, on the other hand, has a higher moisture absorption rate compared to Delrin. It can absorb up to 10% of its weight in water, which can lead to dimensional changes and reduced mechanical properties. However, Nylon's moisture absorption can be advantageous in certain applications where lubrication or swelling is desired, such as in bearings or seals.

4. Temperature Resistance

Delrin has excellent temperature resistance, with a high melting point of around 175°C (347°F). It retains its mechanical properties even at elevated temperatures, making it suitable for applications that require thermal stability. Delrin can also withstand repeated exposure to hot water or steam without significant degradation.

Nylon, on the other hand, has a lower melting point compared to Delrin, typically around 210°C (410°F). While Nylon can handle moderate temperatures, it may start to soften or deform at higher temperatures. However, Nylon's heat resistance can be improved by adding fillers or reinforcing agents, allowing it to be used in higher temperature applications.

5. Machinability

Delrin is known for its excellent machinability, allowing for precise and intricate parts to be manufactured with ease. It can be easily turned, milled, drilled, or tapped, making it a preferred choice for applications that require complex shapes or tight tolerances. Delrin also exhibits low friction during machining, resulting in smooth finishes and reduced tool wear.

Nylon, on the other hand, can be more challenging to machine compared to Delrin. It has a tendency to generate heat during machining, which can cause melting or chip welding. However, with proper cooling and cutting techniques, Nylon can still be machined effectively. Additionally, Nylon's self-lubricating properties can reduce the need for additional lubrication in certain applications.

Conclusion

Delrin and Nylon are both excellent engineering plastics with unique attributes that make them suitable for various applications. Delrin offers exceptional mechanical properties, low friction, and good chemical resistance, making it ideal for load-bearing components. Nylon, on the other hand, excels in toughness, impact resistance, and chemical resistance, making it a preferred choice in applications that require durability and exposure to chemicals.

Ultimately, the choice between Delrin and Nylon depends on the specific requirements of the application. Considering factors such as mechanical properties, chemical resistance, moisture absorption, temperature resistance, and machinability will help in selecting the most appropriate material for a given application.