Nylon is one of the most popular engineering plastics used in CNC machining due to its impressive balance of strength, durability, and machinability. As a thermoplastic material with excellent mechanical properties, nylon is widely used for manufacturing gears, bushings, spacers, bearings, and components in automotive, electrical, and industrial applications.
However, not all nylon materials are the same. Choosing the right nylon grade is crucial for achieving optimal performance, cost-effectiveness, and long-term reliability in your CNC machined parts. This article provides an in-depth guide on the most common nylon grades, their properties, and how to select the ideal grade for your project.
Common Nylon Grades Overview
| Nylon Grade | Tensile Strength (MPa) | Chemical Resistance | Temperature Resistance (°C) | Moisture Absorption (%) | Cost | Typical Applications | Machinability |
| Nylon 6 | 60-85 | Good | -40 to 85 | 1.5-2.5 | Low | Gears, bushings, rollers | Good |
| Nylon 6/6 | 75-100 | Better | -40 to 100 | 1.2-2.5 | Moderate | Automotive parts, fasteners, gears | Good |
| Nylon 4/6 | 80-110 | Better | -40 to 125 | 1.2-2.5 | High | High-temp gears, harsh chemicals | Fair |
| Nylon 12 | 45-70 | Good | -40 to 80 | 0.5-1.0 | Moderate | Seals, flexible parts, tubing | Excellent |
| Glass-Filled Nylon (30% GF) | 150-250 | Better | -40 to 150 | Varies | High | Structural, load-bearing parts | Fair |
Nylon Grades in Detail
Nylon 6
Nylon 6 is the most cost-effective and commonly used grade. It offers good strength, impact resistance, and wear resistance, making it suitable for general-purpose applications like gears, pulleys, and bushings in moderate environments.
Nylon 6/6
Known for higher strength and rigidity than Nylon 6, Nylon 6/6 provides better thermal and chemical resistance. It is ideal for applications exposed to slightly higher temperatures and more demanding mechanical stress.
Nylon 4/6
This premium-grade nylon provides superior heat resistance, chemical stability, and lower moisture absorption. Nylon 4/6 is well-suited for high-temperature applications, industrial equipment, and parts exposed to harsh chemicals.
Nylon 12
Nylon 12 is a unique grade with excellent flexibility, low moisture absorption, and good chemical resistance. It performs well in humid or submerged environments, making it suitable for seals, tubing, and electrical insulation.
Glass-Filled Nylon
Glass-filled nylon is reinforced with glass fibers to significantly enhance strength, stiffness, and dimensional stability. It is the go-to choice for structural parts, automotive components, and high-load applications.
Factors to Consider When Choosing a Nylon Grade
Mechanical Properties
Evaluate your part’s required strength, wear resistance, and stiffness. For high-load or structural components, glass-filled nylon offers superior performance.
Chemical Resistance
Select a nylon grade that resists oils, fuels, solvents, or chemicals your part may contact. Nylon 4/6 and Nylon 12 offer better chemical resistance than Nylon 6 or Nylon 6/6.
Temperature Resistance
Ensure the nylon grade can withstand your application’s operating temperatures. Nylon 4/6 and glass-filled nylon have the highest thermal stability.
Moisture Absorption
Since nylon absorbs moisture, which can affect part dimensions, use Nylon 12 or glass-filled nylon for humid or submerged conditions.
Regulatory Compliance
Ensure compliance with industry-specific standards, such as FDA-approved nylon grades for food and medical applications.
Surface Finish and Aesthetics
Consider the required surface finish, color stability, and appearance of the final product.
Nylon CNC Machining Challenges and Solutions
| Challenge | Solution |
| Warping and Distortion | Optimize fixturing, avoid removing excessive material quickly, and balance clamping pressure. |
| Dimensional Stability | Account for moisture absorption; select low-absorbing grades like Nylon 12. |
| Chip Control | Use sharp cutting tools, proper feed rates, and optimized spindle speeds for effective chip evacuation. |
Nylon CNC Machining vs. Alternative Manufacturing Methods
CNC Machining Nylon — Fast and Flexible
CNC machining is a great choice when you need strong, high-quality nylon parts quickly and in small to medium quantities. It’s perfect for custom parts or prototypes because there are no expensive molds required. You just upload your design, and the machine cuts your part directly from a nylon block.
Best for: Custom parts, small-batch production, prototypes, complex designs
Pros: Fast lead time, tight tolerances, excellent surface finish, wide material choice
Cons: Higher cost per part for large quantities
Injection Molding Nylon — Great for Large Quantities
Injection molding is the go-to method for producing a lot of parts at a lower cost per piece — once you’ve paid for the mold. The process is slower to set up because making the mold takes time and money, but it’s very efficient for large production runs.
Best for: High-volume production of simple to moderately complex parts
Pros: Low cost per part in large volumes, good surface finish, consistent results
Cons: High upfront tooling cost, longer lead time for setup
3D Printing Nylon — Fast and Cost-Effective for Prototypes
3D printing (also called additive manufacturing) is ideal for quickly producing nylon prototypes or low-volume parts with complex shapes. However, the strength and finish of 3D printed nylon may not always match CNC machined parts.
Best for: Rapid prototypes, low-volume parts, highly complex designs
Pros: No tooling cost, fast turnaround, freedom of design
Cons: Lower strength and surface finish compared to CNC machining, limited material types
Quick Comparison Chart
| Method | Best Use | Speed | Cost per Part | Material Options | Surface Finish | Production Volume |
| CNC Machining | Custom parts, prototypes | Fast | Medium | Wide range of nylons | Excellent | Low to Medium |
| Injection Molding | Mass production | Slower setup, fast production | Low (high tooling cost) | Wide range of nylons | Good | High |
| 3D Printing | Prototypes, complex shapes | Very fast | Low to Medium | Limited (mostly Nylon 12) | Fair | Low to Medium |
Conclusion: How to Choose the Right Nylon Grade
Different nylon grades have different strengths, properties, and best-use cases. Picking the right one really depends on what you need your part to do.
Let’s break it down in a simple way.
Think About Strength and Durability
If your part needs to handle a lot of stress, pressure, or heavy loads, you’ll want a tougher nylon grade.
→ Best choice:
Nylon 6/6 — Strong, stiff, and very durable.
Nylon 66 GF (Glass-Filled) — Even stronger with added glass fibers for extra toughness.
Consider Wear Resistance and Low Friction
Need your part to slide, move, or handle constant rubbing without wearing out? Some nylons are made just for that.
→ Best choice:
Nylon with Molybdenum Disulfide (MoS2) — Great for wear resistance and low friction.
Nylon with Oil or Lubricant Fillers — Built-in lubrication for smooth movement.
Think About Moisture Absorption
Nylon naturally absorbs water, which can change its size or shape. If your part will be in wet or humid conditions, you’ll want a nylon grade that handles moisture better.
→ Best choice:
Nylon 12 — Low moisture absorption, stays stable in wet environments.
Nylon 6/12 — A nice balance of strength and moisture resistance.
Look at Temperature Resistance
Will your nylon part need to handle high heat? Some grades are better at this than others.
→ Best choice:
Nylon 6/6 — Handles moderate heat well.
Heat-Stabilized Nylon — Specially designed for higher temperature environments.
Need Food-Safe Material?
If your part will be used in the food or medical industry, make sure to pick a nylon grade that meets safety standards.
→ Best choice:
FDA Approved Nylon Grades — Safe for food contact and easy to clean.
Recommended External Links (Authoritative Sources)
For Nylon Material Properties:
https://www.matweb.com — Comprehensive database for material properties
https://www.plasticsintl.com/plastics-materials/nylon — Nylon Material Types & Properties
https://www.professionalplastics.com/NYLON — Technical Data Sheets for Nylon Grades
For CNC Machining Resources:
https://www.hubs.com/knowledge-base/nylon-for-cnc-machining/ — Nylon for CNC Machining Guide
https://www.machinedesign.com/materials — Engineering Material Selection Advice
https://www.makeitfrom.com/material-properties/Nylon — Nylon Material Comparison
