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Nylon vs POM
Introduction
Nylon and POM are two of the most widely used engineering thermoplastics for injection molded mechanical components.
Both materials can provide good strength, wear resistance, durability, and reliable performance, which is why they are frequently considered for gears, bearings, clips, fasteners, guides, rollers, and other functional plastic parts.
However, Nylon and POM behave differently in actual applications.
Nylon is often selected when toughness, mechanical strength, fatigue resistance, and structural performance are important. POM is commonly preferred when low friction, dimensional stability, low moisture absorption, and precise mechanical movement are higher priorities.
Neither material is universally better.
The right choice depends on load conditions, friction, moisture exposure, dimensional requirements, operating environment, part geometry, and manufacturing requirements.
This guide compares Nylon and POM from an engineering and injection molding perspective to help designers select the appropriate material for their application.
What Is Nylon?
Nylon refers to a family of polyamide materials commonly identified as PA.
Frequently used injection molding grades include PA6, PA66, and various reinforced or modified Nylon formulations.
Nylon is commonly selected because it provides a useful combination of:
- High mechanical strength
- Good toughness
- Excellent wear resistance
- Fatigue resistance
- Good chemical resistance
- Low weight
- Good performance in structural components
Nylon can also be reinforced with glass fiber to increase stiffness, strength, and dimensional performance.
One of its most important engineering characteristics, however, is moisture absorption.
Nylon is hygroscopic and can absorb moisture from the surrounding environment. This can affect dimensions and mechanical behavior, making environmental conditions important when designing precision components.
What Is POM?
POM, or polyoxymethylene, is also commonly known as acetal.
It is a semi-crystalline engineering thermoplastic particularly well suited to precision mechanical components requiring low friction and stable dimensions.
POM is commonly valued for:
- Low coefficient of friction
- Excellent wear resistance
- High stiffness
- Good mechanical strength
- Low moisture absorption
- Excellent dimensional stability
- Smooth surface characteristics
- Reliable repetitive movement
These properties make POM particularly useful for gears, bearings, rollers, guides, latches, mechanical controls, and precision moving parts.
Compared with Nylon, POM absorbs substantially less moisture, which is one reason it is frequently considered for components where dimensional consistency is particularly important.
Nylon vs POM: Quick Comparison
| Engineering Factor | Nylon (PA) | POM (Acetal) |
| Mechanical Strength | High | High |
| Toughness | Excellent | Good |
| Wear Resistance | Excellent | Excellent |
| Friction | Low | Very Low |
| Fatigue Resistance | Excellent | Good to Excellent |
| Moisture Absorption | Higher | Low |
| Dimensional Stability | Environment Dependent | Excellent |
| Stiffness | Good to High | High |
| Surface Characteristics | Good | Smooth |
| Precision Moving Parts | Good | Excellent |
| Typical Strength | Structural performance | Precision mechanical movement |
These comparisons are general guidelines.
Actual properties depend on the specific polymer grade, reinforcement, additives, processing conditions, operating temperature, and environmental exposure.
1. Mechanical Strength and Toughness
Both Nylon and POM provide mechanical performance suitable for many functional injection molded components.
Nylon is particularly attractive where toughness and resistance to repeated loading are important.
Typical examples include:
- Structural brackets
- Clips
- Fasteners
- Mechanical housings
- Load-bearing components
- Gears
Its combination of strength and toughness allows Nylon components to tolerate mechanical loading while maintaining relatively low weight.
POM also offers good strength, but its engineering advantage is often its combination of stiffness, low friction, and dimensional consistency.
For rigid precision mechanisms, POM may therefore be more attractive even when maximum toughness is not the primary design requirement.
Material selection should always consider the type of load involved: static, impact, cyclic, bending, or continuous mechanical stress.
2. Wear and Friction
Wear performance is one area where both materials are frequently considered.
Nylon provides excellent wear resistance and is widely used in gears, rollers, guides, bushings, and other mechanical components.
POM also provides excellent wear behavior but generally offers especially favorable low-friction characteristics.
This makes POM particularly attractive for:
- Sliding mechanisms
- Precision gears
- Bearings
- Guides
- Rollers
- Mechanical controls
- Moving assemblies
For applications requiring smooth movement with limited lubrication, POM is often a strong candidate.
However, friction and wear should not be evaluated from material family alone.
Engineers should consider:
- Mating material
- Surface finish
- Contact pressure
- Sliding speed
- Temperature
- Lubrication
- Duty cycle
- Expected service life
Representative testing may be necessary for critical wear applications.
3. Moisture Absorption
Moisture absorption is one of the most important differences between Nylon and POM.
Nylon naturally absorbs moisture from the surrounding environment.
This moisture can influence:
- Component dimensions
- Stiffness
- Mechanical properties
- Assembly fit
- Long-term dimensional behavior
This does not make Nylon a poor material. It simply means humidity must be considered during engineering design.
For components with tight dimensional tolerances, engineers should evaluate the expected operating environment rather than relying only on dry-as-molded dimensions.
POM has much lower moisture absorption and is therefore generally more predictable in changing humidity conditions. AccuMolds' existing POM guidance specifically identifies its lower moisture absorption relative to Nylon as an important material distinction.
For precision mechanisms, this difference can become a major selection factor.
4. Dimensional Stability
If a component must maintain accurate geometry and clearances, POM often has an advantage.
Its combination of low moisture absorption and good dimensional stability makes it well suited for:
- Precision gears
- Mechanical assemblies
- Sliding components
- Actuator parts
- Metering components
- Control mechanisms
Nylon can also be used successfully in dimensionally controlled parts, especially with appropriate grade selection and engineering design.
Glass-filled Nylon, for example, can provide significantly greater stiffness and improved dimensional performance.
However, reinforcement also introduces new considerations such as fiber orientation, anisotropic shrinkage, warpage, surface appearance, and mold wear.
For either material, tight tolerances should be evaluated during DFM rather than applied uniformly across the drawing.
5. Fatigue and Repeated Loading
Many plastic mechanical components experience thousands or millions of repeated load cycles rather than a single static load.
Examples include:
- Snap features
- Mechanical linkages
- Clips
- Flexible structural components
- Repeatedly loaded gears
Nylon is often attractive in these applications because of its toughness and fatigue performance.
POM also performs effectively in repetitive mechanical systems, especially where smooth motion and low friction are important.
The better material therefore depends on the failure mode the designer is trying to prevent.
If repeated structural loading dominates the requirement, Nylon may have an advantage.
If precise repetitive movement and friction control dominate the requirement, POM may be more appropriate.
6. Temperature Performance
Both Nylon and POM can operate at temperatures beyond those suitable for many commodity plastics, but temperature capability depends strongly on the specific grade.
Different Nylon families also behave differently.
PA6, PA66, heat-stabilized Nylon, glass-filled Nylon, and specialty polyamides should not be treated as identical materials.
Likewise, POM homopolymer and copolymer grades can offer different performance characteristics.
When evaluating temperature, engineers should consider:
- Continuous service temperature
- Short-term temperature peaks
- Mechanical load at temperature
- Thermal cycling
- Creep
- Chemical exposure
- Dimensional requirements
Material supplier data for the actual grade should be reviewed before final selection.
7. Chemical and Environmental Resistance
Both materials provide useful chemical resistance for many engineering applications, but compatibility varies according to the chemical environment.
Consider possible contact with:
- Oils
- Lubricants
- Fuels
- Cleaning agents
- Detergents
- Industrial chemicals
- Automotive fluids
The combination of chemical exposure, stress, temperature, and time can be more important than chemical contact alone.
Outdoor conditions should also be considered.
If the component will experience UV exposure, temperature cycling, humidity, or weathering, a suitable stabilized grade may be required.
For critical applications, resin supplier compatibility data and representative testing should be used before final approval.
8. Injection Molding Considerations
Nylon and POM both require controlled injection molding processes, but their processing priorities differ.
Nylon Processing
Because Nylon is hygroscopic, proper material drying is essential before molding.
Insufficient drying can contribute to:
- Surface defects
- Silver streaks
- Reduced mechanical performance
- Processing instability
AccuMolds' Nylon processing guidance specifically identifies drying as an important step for maintaining molded-part quality.
Process control should also consider mold temperature, melt temperature, filling behavior, cooling, and part geometry.
POM Processing
POM has lower moisture sensitivity, but stable thermal processing remains important.
Key considerations include:
- Controlled melt temperature
- Appropriate mold temperature
- Avoiding excessive residence time
- Preventing material degradation
- Proper ventilation
- Consistent cooling
AccuMolds' existing POM guide similarly emphasizes stable processing temperature and avoiding excessive residence time.
For either material, good tooling and process control are necessary for consistent mechanical and dimensional performance.
9. Reinforced Nylon vs POM
The comparison becomes more complex when reinforced Nylon grades are considered.
Glass-filled Nylon can offer:
- Higher stiffness
- Increased strength
- Better creep resistance
- Improved dimensional stability
This can make reinforced Nylon competitive with POM in applications where standard Nylon may not provide sufficient rigidity.
However, reinforcement can also affect:
- Flow behavior
- Fiber orientation
- Shrinkage
- Warpage
- Surface finish
- Weld-line strength
- Tool wear
Engineers should therefore compare specific resin grades rather than assuming that all Nylon materials behave the same way.
10. Cost and Manufacturing Considerations
Nylon and POM are both widely used engineering materials, and cost differences depend on the selected grade, reinforcement, supplier, production volume, and market conditions.
The lowest resin price should not determine the final choice.
Total manufacturing cost may include:
- Material preparation
- Cycle time
- Scrap
- Mold complexity
- Dimensional control
- Inspection
- Assembly
- Secondary operations
- Product life
For example, a material that costs slightly more but maintains critical dimensions more consistently may reduce assembly or quality problems.
Material selection should therefore be based on total product performance and production requirements.
When Should You Choose Nylon?
Nylon is often the stronger candidate when the application prioritizes:
- Mechanical toughness
- Structural strength
- Fatigue resistance
- Wear resistance
- Repeated loading
- Lightweight structural performance
Typical applications include:
- Gears
- Clips and fasteners
- Structural brackets
- Mechanical housings
- Rollers
- Automotive components
- Industrial machinery parts
Nylon is particularly useful when the design requires a durable structural engineering plastic and moisture-related dimensional changes can be accommodated or controlled.
When Should You Choose POM?
POM may be the better choice when the component prioritizes:
- Low friction
- Smooth mechanical movement
- Excellent dimensional stability
- Low moisture absorption
- High stiffness
- Precision geometry
Typical applications include:
- Precision gears
- Bearings
- Bushings
- Rollers
- Sliding guides
- Mechanical controls
- Actuator components
- Precision assemblies
POM is especially attractive when consistent clearances and predictable mechanical movement are critical.
Nylon or POM: How Should Engineers Decide?
Start with the application rather than selecting a material based on familiarity.
Ask:
- Is structural toughness or dimensional precision more important?
- Will the component experience repeated mechanical loading?
- Does it slide or rotate against another surface?
- How important is low friction?
- Will humidity affect the component?
- How tight are the dimensional tolerances?
- Does the design require glass reinforcement?
- What temperature and chemical environment will the part experience?
- What production volume is expected?
- Which material provides the required performance without unnecessary manufacturing complexity?
A simplified rule is:
Choose Nylon when toughness, fatigue resistance, and structural performance dominate.
Choose POM when low friction, low moisture absorption, and dimensional precision dominate.
The final decision should still be based on a specific material grade, application requirements, DFM review, and validation testing where necessary.
Need Engineering Support?
Choosing between Nylon, POM, reinforced Nylon, or another engineering thermoplastic requires more than comparing basic material properties.
AccuMolds can help evaluate your application requirements, material options, part geometry, wall thickness, tolerances, gate strategy, tooling feasibility, and expected production volume before mold manufacturing begins.
Our engineering capabilities support projects from material selection and DFM analysis through precision mold development, injection molding, inspection, and scalable production. AccuMolds' current custom molding workflow also accepts CAD files, material requirements, estimated production volume, surface finish, and tolerance requirements for DFM review and quotation.
Send us your 2D or 3D CAD files together with your material requirements, quantities, tolerances, surface requirements, and application information for project evaluation.
