Delrin vs Nylon in CNC Machining Applications

Delrin vs Nylon in CNC Machining: Which Plastic Performs Better for Precision Parts?

When customers ask us to machine plastic parts, one question comes up almost every week:

“Should we use Delrin or Nylon for CNC machining?"

On paper, both look similar.
In real factory production, however, the difference is huge.

Over the past 12 years running CNC machining for industrial buyers, we’ve processed 50,000+ Delrin and Nylon components for gears, bushings, sliders, wear plates, and automation parts.

We’ve seen:

• Nylon warp after humidity exposure
• Delrin hold ±0.01 mm tolerance for months
• Wrong material choices cause 30–40% scrap rate

This guide shares real machining data, practical fixes, and buyer selection advice — not textbook theory.

Delrin vs Nylon: Quick Comparison Table

Quick rule we use in our factory:

• Tight tolerance → Delrin
• Shock load or abrasion → Nylon

What is Delrin in CNC Machining?

Delrin (Polyoxymethylene / Acetal / POM) is one of the most dimensionally stable engineering plastics we machine.

Our shop experience:

When milling Delrin:

• Chips break cleanly
• No stringing
• Minimal heat build-up
• Tool wear very low

This means:
✔ faster feed rates
✔ better surface finish
✔ stable tolerance after machining

Real production data (our factory test)

Material: 20 mm plate
Process: CNC milling

Delrin clearly wins for precision mechanical assemblies.

Typical Delrin CNC parts

• Precision gears
• Bushings
• Linear slide blocks
• Robot components
• Semiconductor fixtures

What is Nylon in CNC Machining?

Nylon (PA6 / PA66) is tougher and more impact resistant.

However, from a machining standpoint, it’s more “difficult".

Problems we frequently see:

• Stringy chips wrapping tools
• Heat deformation
• Moisture swelling
• Post-machining warping

In summer (humidity > 70%), we measured 0.15–0.25 mm growth on 200 mm parts within one week.

For tight tolerance jobs, this becomes a serious issue.

But Nylon shines when:

✔ heavy load
✔ sliding friction
✔ impact shock
✔ low cost required

Typical Nylon CNC parts

• Wear pads
• Conveyor rollers
• Heavy-duty bushings
• Impact guards
• Agricultural machinery parts

How to Choose: Step-by-Step Buyer Selection Guide

Follow this process we use with B2B customers:

Step 1 — Check tolerance

• ±0.02 mm or tighter → Delrin

• ±0.05 mm → Either works

Step 2 — Check environment

• High humidity → Avoid Nylon
• Outdoor use → Delrin safer

Step 3 — Check load type

• Continuous wear → Nylon
• Precision motion → Delrin

Step 4 — Check budget

• Low cost priority → Nylon
• Performance priority → Delrin

Real Case Study from Our Shop

Client: Automation equipment manufacturer

Part: Linear guide slider
Tolerance: ±0.015 mm

Originally used: Nylon

Problems:

• Warping after assembly
• Jamming on aluminum rail
• 18% rejection rate

Our solution:

Changed to Delrin (POM-C)

Results:

• Tolerance stable
• Friction reduced 22%
• Scrap rate → 2%
• Lifetime increased 1.8*

Customer saved ~$12,000/year in maintenance.

This is why we now default to Delrin for precision motion parts.

Machining Tips from Our Engineers

Delrin CNC tips

• Use sharp carbide tools
• High feed, medium speed
• No coolant needed
• Achieve mirror finish easily

Nylon CNC tips

• Use air blast cooling
• Lower speed to avoid melting
• Rough + finish passes
• Pre-dry material before machining

Drying Nylon alone reduced our warping issues by 40%.

Cost Comparison for Buyers

Although Delrin costs ~15–25% more,
total cost per good part is often lower due to reduced scrap.