Spur Gear: Module Range 0.5 to 25 mm

Component Specifications

Definition

A spur gear is a fundamental mechanical component characterized by its cylindrical shape and straight-cut teeth that are oriented parallel to the gear's axis of rotation. It is designed to mesh with another spur gear on a parallel shaft to transmit rotational motion and torque efficiently. The teeth engage along a line of contact, providing smooth power transfer with minimal axial thrust. These gears are manufactured to precise geometric specifications including module/diametral pitch, pressure angle, number of teeth, and face width to ensure proper meshing and load distribution. They are critical elements in gear trains, speed reducers, and various transmission systems where parallel shaft arrangements are required.

Working Principle

Spur gears operate on the principle of conjugate action between meshing teeth profiles. As one gear (the driver) rotates, its teeth engage with the teeth of the mating gear (the driven), transmitting rotational motion and torque through direct contact. The involute tooth profile ensures constant velocity ratio and smooth engagement/disengagement. Power transmission occurs along the line of action tangent to the base circles, with forces acting radially and tangentially to create rotational motion. The gear ratio is determined by the ratio of the number of teeth on the driven gear to the number on the driver gear.

Materials

Typically manufactured from alloy steels (AISI 4140, 4340, 8620), carbon steels (1045, 4140), stainless steels (303, 304, 316), cast iron (gray, ductile), brass, bronze, or engineered plastics (nylon, acetal, polycarbonate). Heat treatment processes include carburizing, nitriding, induction hardening, or through-hardening to achieve surface hardness of 55-65 HRC for steel gears. Material selection depends on application requirements for strength, wear resistance, corrosion resistance, noise reduction, and cost.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Backlash	0.05 to 0.4 mm depending on precision class
Face Width	3 to 10 times module
Module Range	0.5 to 25 mm
Tooth Profile	Involute (standard)
Accuracy Grade	ISO 1328 Class 3 to 12, AGMA Q3 to Q15
Pressure Angle	20° (standard), 14.5° (historical)
Surface Finish	0.4 to 3.2 μm Ra
Diametral Pitch Range	1 to 120 DP
Maximum Pitch Line Velocity	Up to 25 m/s for precision gears

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 1328, ISO 6336, AGMA 2001, AGMA 2015, DIN 3960, DIN 3990, JIS B 1702

Parent Products

This component is used in the following industrial products

Gear Train

A mechanical system consisting of two or more gears meshed together to transmit motion and torque between rotating shafts.

View Product Details

Gear Train (Spur/Helical/Planetary)

A mechanical assembly of multiple gears that transmits and modifies torque and speed from a motor to an output shaft.

View Product Details

Engineering Analysis

Risks & Mitigation

Tooth bending fatigue failure
Pitting and surface wear
Scoring and scuffing
Noise and vibration at high speeds
Misalignment causing uneven load distribution
Inadequate lubrication leading to premature failure
Backlash accumulation affecting precision

FMEA Triads

Trigger: Insufficient hardness or improper heat treatment
Failure: Premature tooth wear and pitting
Mitigation: Specify appropriate material grade with proper heat treatment; implement surface hardening processes; maintain adequate lubrication with correct viscosity

Trigger: Misalignment during installation or operation
Failure: Uneven load distribution leading to localized tooth breakage
Mitigation: Use precision alignment tools during installation; implement regular alignment checks; incorporate flexible couplings; design with proper tolerances and fits

Trigger: Inadequate lubrication or contamination
Failure: Scoring, scuffing, and accelerated wear
Mitigation: Establish proper lubrication schedule with recommended oil grade; implement filtration systems; use sealed gear housings; monitor oil condition regularly

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Tooth profile tolerance per ISO 1328 Class 5-8 for industrial applications; Runout tolerance typically 0.02-0.05 mm; Center distance tolerance ±0.05-0.2 mm depending on size and application

Test Method

Coordinate measuring machine (CMM) for geometric verification; Gear rolling test for composite error; Hardness testing (Rockwell C); Surface roughness measurement; Dye penetrant or magnetic particle inspection for crack detection; Dynamic testing under load for noise and vibration analysis

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

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Manufacturers of Spur Gear

Manufacturer profiles associated with Spur Gear.

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Frequently Asked Questions

What are the main advantages of spur gears?

Spur gears offer high efficiency (95-99%), simple design, ease of manufacturing, cost-effectiveness, reliable performance, and ability to transmit high torque loads. They provide constant velocity ratio and are suitable for a wide range of industrial applications.

What are the limitations of spur gears?

Spur gears generate more noise at high speeds compared to helical gears, cannot transmit motion between non-parallel shafts, create only radial loads (no axial thrust), and have lower load capacity per tooth compared to some other gear types at similar sizes.

How do I select the right spur gear for my application?

Consider torque requirements, speed ratio, shaft arrangement, operating environment, space constraints, noise limitations, and service life. Calculate based on module/pitch, number of teeth, face width, material strength, and verify against bending and contact stress using ISO 6336 or AGMA standards.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Spur Gear