A gear may appear to be a simple mechanical component, yet selecting the wrong material can lead to:

• accelerated wear

• premature corrosion

• noise and vibration

• efficiency losses

• early system failure

Choosing the correct material ensures reliability, long service life, and optimal performance.

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Step 1: Define Operating Conditions

Before selecting a material, define:

✔ torque and load
✔ rotational speed
✔ gear type (spur / helical / bevel / worm)
✔ environment (humidity, seawater, chemicals)
✔ noise and precision requirements
✔ lubrication and maintenance
✔ weight limitations

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Step 2: Main Gear Material Families

Carbon & Alloy Steels

Examples:
214M15 / 045M10, EN8 (080M40), EN24 (817M40), EN36 (655M13)

Advantages

✔ high mechanical strength
✔ excellent wear resistance
✔ suitable for heavy loads
✔ can be hardened or case hardened

Limitations

❌ susceptible to corrosion
❌ require coating or lubrication in wet environments

Typical Uses
industrial gearboxes, heavy equipment, power transmission.

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Case Hardened Steels

EN36 / EN24 hardened

✔ extremely hard surface layer
✔ tough core for shock resistance
✔ superior wear resistance

❗ corrosion protection required in wet environments.

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Stainless Steel

Common grades: 303, 304, 316

Advantages

✔ excellent corrosion resistance
✔ minimal maintenance
✔ suitable for wet and marine environments

Limitations

❌ lower strength compared to hardened steels
❌ lower wear resistance

Notes

• 303 – easy machining, reduced chloride resistance

• 304 – good for general humidity

• 316 – preferred for marine environments

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Bronze & Phosphor Bronze

Common grades: PB1, PB2, Aluminum Bronze

Advantages

✔ low wear and friction
✔ excellent corrosion resistance
✔ outstanding seawater resistance
✔ ideal when meshing with steel

Typical Uses
worm gears, marine equipment, wet environments.

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Engineering Plastics

Examples: Delrin (POM), Nylon (PA), PEEK

Advantages

✔ very quiet operation
✔ corrosion-free
✔ lightweight
✔ low friction

Limitations

❌ limited load capacity
❌ creep under long-term load

Applications
medical equipment, light automation, food machinery.

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Step 3: Material Comparison

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Step 4: Matching Materials to Applications

Heavy Loads

✔ EN24 or EN36 hardened

Wet or Humid Environments

✔ coated steel
✔ stainless steel 304/316

Marine / Seawater Exposure

✔ Stainless 316
✔ PB2
✔ Aluminum Bronze

Worm Gear Systems

✔ wheel: PB2
✔ worm: hardened steel

Noise Reduction & Precision

✔ Delrin / POM

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Corrosion – A Critical Design Factor

Water and chlorides accelerate corrosion and can cause:

• surface pitting

• increased wear

• reduced gear accuracy

Mitigation Methods

✔ select corrosion-resistant materials
✔ electroless nickel coating
✔ zinc-nickel plating
✔ proper lubrication
✔ sealing and protection

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Best Practice: Material Pairing

Often the optimal solution is combining materials:

• hardened steel worm + PB2 wheel

• hardened steel gear + Delrin mating gear to reduce noise

• hardened steel with protective coating for corrosion resistance

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Common Material Selection Mistakes

❌ hardened steel without corrosion protection in wet environments
❌ plastic gears used under high load
❌ stainless steel selected for heavy load instead of hardened steel
❌ ignoring proper material pairing

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CASE STUDY

Subsea Drive Transmission System

System Requirements

• operating torque: 420 Nm

• peak torque: 700 Nm

• speed: 90 RPM

• environment: continuous seawater immersion

• duty cycle: 24/7

• maintenance: minimal

• requirement: quiet and reliable operation

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Engineering Challenges

✔ chloride-induced corrosion
✔ high-load wear resistance
✔ prevention of galling and seizure
✔ continuous operation with minimal maintenance

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Materials Considered

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Selected Solution

✔ Worm: hardened EN36 with electroless nickel coating
✔ Wheel: PB2 phosphor bronze

Performance Results

✔ excellent corrosion resistance
✔ low friction and smooth operation
✔ minimal wear
✔ quiet operation
✔ extended service life

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FAQ – Frequently Asked Questions

What is the strongest gear material?

Hardened alloy steels such as EN24 or EN36 provide the highest strength and wear resistance.

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Which material is best for seawater environments?

Stainless steel 316, aluminum bronze, or PB2 phosphor bronze are leading choices.

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Why is bronze used in worm gears?

Bronze reduces friction, resists wear, and prevents galling when meshing with steel worms.

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Can plastic gears replace metal gears?

Yes, in low-load applications where quiet operation and corrosion resistance are priorities.

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Why combine different materials?

Proper material pairing reduces wear, improves efficiency, and extends system life.

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Is stainless steel always better in wet environments?

Not necessarily. Under heavy loads and wear conditions, hardened steel with protection or bronze pairing may perform better.

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Conclusion

Selecting the correct gear material is a critical engineering decision affecting:

✔ system reliability
✔ service life
✔ efficiency
✔ maintenance requirements

Understanding operating conditions and material behavior enables optimal performance even in the harshest environments.

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Need assistance selecting the right gear material?
Amironic supports engineers in choosing reliable motion and power transmission solutions for industrial, defense, and harsh-environment applications.