What is a nylon bushing and how does it work?

What is a nylon bushing and how does it work?

A nylon bushing is a bearing element made from polyamide (commonly PA6 or PA6/6) designed to support rotating or sliding shafts with low friction and good wear resistance. It works by providing a sacrificial, low-friction interface between moving parts, absorbing shock and isolating vibration. Nylon’s natural lubricity and ability to deform slightly under load allow it to conform to mating surfaces and distribute contact stresses, reducing metal‑to‑metal wear and the need for frequent lubrication in many applications.

Which nylon grades are used for bushings and what are their key differences?

Common grades used for bushings include unfilled and filled PA6 and PA6/6. Typical distinctions:

• PA6 (Nylon 6): good toughness, impact resistance, slightly higher moisture uptake than PA6/6; suitable for general-purpose bushings.
• PA6/6 (Nylon 6/6): higher heat resistance and stiffness; often specified where dimensional stability at elevated temperature is needed.
• Glass-filled nylon: increased stiffness, higher load capacity and lower creep, but higher wear on mating shafts and reduced impact resistance.
• Lubricated or PTFE/solid-lubricant-filled grades: reduced coefficient of friction and improved dry-running wear life.

Selection depends on operating temperature, load, speed, lubrication plan and environmental exposure.

What are the typical mechanical and thermal properties relevant to procurement?

Material properties vary by grade and manufacturer, but typical ranges (representative) to consider when specifying bushings:

• Tensile strength: ~60–100 MPa (varies with grade and filler content).
• Flexural modulus: ~2–4 GPa unfilled; higher for glass-filled grades.
• Operating temperature: continuous use often between -40°C and +80°C for general nylon; some PA6/6 or filled grades can withstand short-term peaks over 100°C. Verify specific grade limits with supplier.
• Moisture absorption: typical equilibrium moisture uptake at 23°C/50% RH ~1.5–3.5% (affects dimensions and some mechanical properties).
• Coefficient of friction: dry sliding vs steel commonly ~0.2–0.4; solid-lubricant grades reduce this substantially.

Always request supplier datasheets for exact numbers and conditioned-test results (dry vs saturated).

How do fillers and additives change performance?

Fillers are commonly used to tune hardness, stiffness, wear and thermal behaviour:

• Glass fiber: raises stiffness, strength and heat deflection temperature; reduces creep but increases abrasion on mating shafts.
• PTFE or graphite: lowers friction and improves dry‑running wear life.
• Molybdenum disulfide (MoS2): improves wear resistance under sliding contact.
• Impact modifiers: maintain toughness for shock-loaded bushings.

Trade-offs are typical: higher load capacity vs increased shaft wear or reduced impact toughness. Define the dominant failure mode when specifying additives.

When should you choose nylon bushings over metal bearings or other plastics?

Choose nylon bushings when you need a lightweight, corrosion-resistant, and low-maintenance bearing with good vibration dampening and electrical isolation. Typical use-cases include appliances, conveyor guides, low-to-moderate-load rotating shafts, and noise-sensitive assemblies. Consider metal bearings when you require very high radial loads, very tight dimensional stability at high temperature, or ultra-high rotational speeds. Other polymers (e.g., PTFE composites, POM/Acetal, UHMW) may be better where chemical resistance, lower moisture uptake, or extreme low friction are primary requirements.

What design and tolerance practices improve bushing performance?

Design considerations and procurement specifications that reduce risk:

• Specify bore and shaft fits using clear tolerance classes; interference press fits are common for housed bushings, while slip fits are used for removable parts.
• Account for nylon’s moisture conditioning — specify whether dimensions are measured dry‑as‑molded or after conditioning (equilibrium humidity).
• Design for thermal and load creep: include radial clearance for shaft expansion or use glass-filled grades to reduce creep under continuous load.
• Include chamfers and lead-ins to ease installation and avoid edge damage to the bushing during press-fit assembly.
• Define acceptable runout and shaft surface finish. For many nylon bushings, a smooth ground or polished shaft (Ra well below 1 μm for precision) extends wear life; for lubricated applications, roughness can be slightly higher but controlled peaks should be avoided.

How does humidity and chemical exposure affect nylon bushings?

Nylon is hygroscopic — it absorbs water from the environment, which softens the polymer and changes dimensions and mechanical properties. Typical effects:

• Increased toughness but reduced stiffness and strength with higher moisture content.
• Dimensional growth (important for tight-tolerance fits).
• Some solvents (strong acids, phenolics, certain hydrocarbons) can degrade nylon; aliphatic hydrocarbons and many common cleaners are generally OK but check chemical compatibility for specific chemicals and concentrations.

Procurement tip: specify conditioning state (dry/wet) for critical dimensions and request chemical compatibility data from the supplier.

What testing and acceptance criteria should buyers require?

Include the following in purchase specifications to ensure predictable performance:

• Material certification and grade designation (e.g., PA6, PA6/6, filled grade code).
• Dimensional tolerances and inspection method (e.g., ISO 286/IT grades or supplier standard). State whether measurements are in conditioned state.
• Mechanical property test reports (tensile, hardness, wear testing if critical) and test conditions (temperature, humidity).
• Surface finish and shaft compatibility recommendations.
• Batch traceability and certificate of conformity; list applicable regulations (RoHS, REACH) if required.
• Sample evaluation or run-in test protocol for critical applications (e.g., 24–100 h bench wear test under expected load/speed/lubrication).

What are common failure modes and how can procurement prevent them?

Common failure modes include excessive wear, dimensional creep, thermal softening, chemical attack and seizure. Preventative procurement actions:

• Specify appropriate grade and fillers for load and temperature.
• Define installation procedures (press fit tools, speeds, temperatures) to avoid crushing or melting bushings.
• Require supplier recommendations for mating shaft hardness and finish to minimize abrasive wear.
• Design replaceability into assemblies (service life planning) and order replacement spares.

Procurement checklist for engineering plastics buyers

Before placing a production order, confirm:

1. Exact material grade and any fillers or solid lubricants.
2. Dimensional tolerances, measurement state (dry/conditioned), and inspection method.
3. Operating temperature, load, speed and expected environmental exposures.
4. Required certifications and regulatory compliance (RoHS, REACH, food contact if applicable).
5. Sample approval, run-in wear testing or lab validation plan for critical parts.
6. Traceability, lot marking and shelf-life/storage instructions.
7. Supplier technical support and post-sales engineering assistance.

Summary — Why choose nylon bushings and final buyer recommendations

Nylon bushings offer a balance of cost, machinability, corrosion resistance and low-friction performance for many low-to-moderate-load applications. For procurement: specify the material grade and conditioning state, request datasheets and test reports, define tolerances and installation methods, and if possible, run a representative wear test before large production orders. When in doubt, consult your material supplier or an application engineer with operating case details (load, speed, environment) to select the right filled or unfilled variant.

Brand note — Bost advantages

Bost’s advantages for engineering buyers typically include a broad portfolio of nylon bushing options and custom machining capabilities, dedicated application support, and quicker prototyping for fit and function checks. Bost can provide material traceability, tailored finishing and advice on grade selection and installation — useful for reducing development time and ensuring consistent production performance. (Buyers should confirm the exact service offerings, quality certifications and lead times with Bost directly.)

References

• MatWeb: Property data for Nylon 6 and Nylon 6/6 (multiple datasheets). Accessed 2026-02-03. https://www.matweb.com
• McMaster-Carr: Nylon bushings and plain bearings product descriptions and application notes. Accessed 2026-02-03. https://www.mcmaster.com
• igus: Plain bearings (iglidur) material guides and dry-running bearing data. Accessed 2026-02-03. https://www.igus.com
• Plastics Technology / PlasticsToday: Articles on fillers, wear and selection of engineering plastics. Accessed 2026-02-03. https://www.plasticstoday.com and https://www.ptonline.com
• Engineering Toolbox & general polymer reference tables (for typical ranges and design guidance). Accessed 2026-02-03. https://www.engineeringtoolbox.com