Nylon vs Delrin (POM): Which Engineering Plastic Is Better for CNC Machined Parts?

Choosing between Nylon and Delrin can stall a project fast. Both are strong engineering plastics, but the wrong pick can lead to wear, warping, tolerance issues, and higher manufacturing costs.

Delrin (POM) is generally the better choice for precision CNC machined parts because it offers superior dimensional stability, lower moisture absorption, better machinability, and lower friction. Nylon is usually the better option when impact resistance, toughness, and wear performance are the primary requirements.

I always tell my guys: Delrin is for when you need precision that stays put, while Nylon is the one I reach for when a part needs to be tough enough to take some abuse.

What Are the Differences Between Nylon and Delrin?

Many engineers compare Nylon and Delrin because both are widely used engineering plastics. They often appear in gears, bushings, rollers, wear components, and automation equipment. The challenge is understanding where their strengths and weaknesses differ.

The main difference between Nylon and Delrin is that Delrin provides better dimensional stability, lower friction, and easier machining, while Nylon offers greater toughness, impact resistance, and wear resistance. Delrin is typically preferred for precision parts, while Nylon is often chosen for demanding wear applications.

Understanding the Material Differences

Nylon and Delrin belong to different polymer families. Nylon is a polyamide material known for its toughness and abrasion resistance. Delrin is an acetal resin developed to provide dimensional stability, low friction, and consistent mechanical performance.

One of the most important differences is moisture absorption. Nylon naturally absorbs moisture from the surrounding environment. This can improve toughness, but it can also cause dimensional growth. Delrin absorbs very little moisture, which allows parts to maintain their original dimensions for much longer periods.

Key Property Comparison

Property	Nylon (PA)	Delrin (POM)
Stiffness	Moderate	High
Toughness	Excellent	Good
Wear Resistance	Excellent	Very Good
Moisture Absorption	High	Very Low
Dimensional Stability	Good	Excellent
Friction Coefficient	Low	Very Low
Machinability	Good	Excellent
Chemical Resistance	Good	Excellent

What This Means in Practice

When I work on automation projects, Delrin is often chosen for components that require accurate positioning and smooth motion¹. Nylon is usually selected when impact loads, vibration, or abrasive contact are expected. Neither material is universally better. The right choice depends on the application's priorities.

For engineers evaluating plastic materials, understanding the strengths of Nylon material properties and applications can help narrow the selection process before comparing it directly against Delrin.

Nylon vs Delrin Material Properties and CNC Machining Performance?

Material performance affects not only how a part functions but also how easily it can be machined and how stable it remains after manufacturing.

Delrin machines more cleanly, holds tighter tolerances, and maintains dimensional stability better than Nylon. Nylon offers superior toughness and impact resistance but may experience slight dimensional changes due to moisture absorption and internal material stresses.

How These Materials Machine

As a machinist, I notice the difference immediately once cutting begins.

Delrin produces short, clean chips and typically leaves an excellent surface finish. It machines consistently and rarely causes problems with chip control. Tight tolerances are easier to maintain because the material remains dimensionally stable.

Nylon behaves differently. It tends to produce long, stringy chips that require careful management. It is also more flexible than Delrin, which means heat buildup and part movement must be monitored during machining.

CNC Machining Comparison

Machining Factor	Nylon	Delrin
Surface Finish	Good	Excellent
Chip Formation	Stringy	Clean
Tool Wear	Low	Low
Tolerance Capability	Good	Excellent
Dimensional Stability	Moderate	Excellent
Heat Sensitivity	Moderate	Low
Post-Machining Movement	Possible	Minimal

Real Manufacturing Case Study

Several years ago, a customer producing packaging equipment approached us with an issue involving conveyor guide bushings. The original Nylon bushings worked well initially but experienced dimensional growth after operating in a humid environment.

Project Parameters

Item	Nylon Version	Delrin Version
Material	PA6 Nylon	POM Delrin
Shaft Diameter	20 mm	20 mm
Bushing OD	32 mm	32 mm
Operating Load	450 N	450 N
Operating Temperature	40°C	40°C
Relative Humidity	80-90%	80-90%
Production Volume	8,000 pcs/year	8,000 pcs/year
Tolerance Requirement	±0.03 mm	±0.03 mm

Results After Six Months

Performance Metric	Nylon	Delrin
Dimensional Change	+0.08 mm	+0.01 mm
Wear Performance	Excellent	Excellent
Friction Stability	Moderate	Excellent
Maintenance Frequency	Monthly	Quarterly
Customer Feedback	Good	Excellent

The customer eventually switched to Delrin because dimensional consistency was more important than impact resistance in their application.

Nylon vs Delrin Applications?

The best material depends heavily on the application. I rarely think of Nylon and Delrin as direct competitors. I see them as solutions for different engineering problems.

Nylon is best suited for wear-resistant, impact-resistant, and heavy-duty industrial components, while Delrin is ideal for precision gears, bushings, bearings, and low-friction mechanical assemblies that require tight dimensional control.

Common Nylon Applications

Nylon performs extremely well in demanding industrial environments where wear and impact are concerns.²

Typical applications include:

• Industrial gears
• Conveyor rollers
• Wear pads
• Chain guides
• Bushings
• Guide rails
• Impact-resistant housings
• Material handling components

I often recommend Nylon for factory equipment that operates under heavy loads or experiences repeated mechanical shock.

Common Delrin Applications

Delrin is often selected when precision and smooth movement are required.³

Typical applications include:

• Precision gears
• Bearings
• Bushings
• Valve components
• Medical device parts
• Automation equipment
• Electrical insulators
• Sliding mechanisms

Industry Application Examples

Industry	Nylon Applications	Delrin Applications
Industrial Automation	Wear Strips	Precision Gears
Automotive	Chain Guides	Fuel System Components
Medical Equipment	Protective Covers	Device Fixtures
Consumer Products	Durable Structural Parts	Sliding Components
Robotics	Wear Components	Motion Control Parts

The tighter the tolerance requirement, the more likely I am to recommend Delrin.

How to Choose Between Nylon and Delrin?

Many engineers ask which material is better. The answer depends on what matters most in the design.

Choose Delrin when dimensional stability, precision, low friction, and tight tolerances are critical. Choose Nylon when impact resistance, wear resistance, load-bearing capability, and toughness are the primary design priorities.

A Simple Decision Framework

Material selection becomes easier when the primary design requirement is identified first.

Requirement	Recommended Material
Tight Tolerances	Delrin
Low Friction	Delrin
High Dimensional Stability	Delrin
High Impact Resistance	Nylon
Heavy Wear Conditions	Nylon
Shock Loading	Nylon
Humid Environment	Delrin
Precision Motion Components	Delrin

Questions I Ask Before Making a Recommendation

Before selecting a material, I typically ask:

1. What tolerance must the part maintain?
2. Will humidity affect the operating environment?
3. Does the part experience shock loading?
4. Is low friction important?
5. Does the assembly require long-term dimensional stability?
6. What is the expected service life?

The answers usually make the material choice straightforward.

CNC Machining Services for Nylon and Delrin Parts?

Even the best engineering plastic can underperform if it is machined incorrectly. Tooling, workholding, and machining strategy all affect final part quality.

Professional CNC machining services ensure Nylon and Delrin parts achieve the required tolerances, surface finishes, and long-term performance by applying the correct machining parameters, fixturing methods, and quality control procedures.

Important Machining Considerations

At Allied Metal, I regularly machine both Nylon and Delrin parts for customers in aerospace, robotics, automation, medical equipment, and industrial machinery industries.

For Delrin projects, I focus on:

• Precision tolerance control
• Excellent surface finishes
• Stable fixturing
• Consistent repeatability

For Nylon projects, I pay close attention to:

• Heat management
• Chip evacuation
• Material stabilization
• Dimensional control

What Engineers Should Look for in a CNC Supplier

Capability	Why It Matters
Material Certification	Verifies material quality
Precision Machining	Ensures assembly fit
Plastic Machining Expertise	Reduces manufacturing risk
Quality Inspection	Improves consistency
Rapid Prototyping Support	Speeds development
Production Scalability	Supports future growth

Engineers who require custom plastic components often benefit from working with a supplier that specializes in both Delrin and Nylon CNC machining services, especially when a project moves from prototyping into production.

Conclusion

Delrin and Nylon are both outstanding engineering plastics, but they solve different problems. Delrin delivers superior precision, dimensional stability, and low-friction performance, making it the preferred choice for tight-tolerance CNC machined parts. Nylon excels in demanding environments where toughness, wear resistance, and impact strength matter most. When the material selection matches the operating conditions, both materials can provide exceptional performance, long service life, and cost-effective manufacturing results.

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