Key Pins: Diameter 3mm to 20mm (common range)

Component Specifications

Definition

Key pins are hardened cylindrical dowel pins that fit into matching keyways on a shaft and its mounted component (e.g., gear, pulley, tumbler) in a tumbler set assembly. They transmit torque and rotational forces while maintaining precise alignment, ensuring synchronized operation. Typically press-fit or secured with set screws, they are critical for preventing slippage and maintaining positional accuracy in high-precision mechanical systems.

Working Principle

Key pins operate on the principle of positive mechanical interference. They are inserted into aligned keyways on both the shaft and the hub of a rotating component, creating a rigid connection that transfers torque and prevents relative rotational or axial movement. This ensures the component rotates exactly with the shaft, maintaining timing and alignment in the tumbler set mechanism.

Materials

Typically made from alloy steel (e.g., AISI 4140, 4340) or stainless steel (e.g., 316, 17-4 PH), often heat-treated to HRC 45-55 for high strength and wear resistance. Surface finishes may include black oxide, zinc plating, or nitriding for corrosion protection.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Length	10mm to 100mm (customizable)
Diameter	3mm to 20mm (common range)
Hardness	HRC 45-55
Tolerance	h6 or h7 (ISO)
Surface Finish	Ra 0.8μm to 1.6μm

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 8734, DIN 6325, DIN 7

Parent Products

This component is used in the following industrial products

Tumbler Set

A set of precision pins or tumblers within an ignition lock cylinder that aligns with the key cuts to enable rotation and vehicle starting.

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Engineering Analysis

Risks & Mitigation

Shear failure under excessive torque
Wear and fretting in keyways
Misalignment causing binding or premature failure
Corrosion in harsh environments

FMEA Triads

Trigger: Insufficient hardness or material strength
Failure: Shear failure under high torque loads
Mitigation: Use alloy steel with proper heat treatment; specify hardness HRC 45+; conduct torque testing.

Trigger: Poor keyway machining or misalignment
Failure: Binding, uneven wear, or component slippage
Mitigation: Ensure precise keyway dimensions per ISO/DIN standards; use alignment tools during assembly; inspect with gauges.

Industrial Ecosystem

Compatible With

Tumbler sets, gearboxes, conveyor systems, indexing mechanisms

Typical Suppliers & Equivalents

SKF, Misumi, Bosch Rexroth, Jergens

Compliance & Inspection

Tolerance

Diameter tolerance h6/h7 per ISO 286, length tolerance ±0.1mm

Test Method

Torque testing per ISO 898-1, hardness testing per ISO 6508, dimensional inspection with micrometers and gauges

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.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Key Pins

Manufacturer profiles associated with Key Pins.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the difference between a key pin and a standard dowel pin?

Key pins are specifically designed to fit into keyways on shafts and hubs to transmit torque, while dowel pins are generally used for alignment without torque transmission. Key pins often have tighter tolerances and higher hardness.

How are key pins installed in a tumbler set?

They are typically press-fit into pre-machined keyways on both the shaft and component, sometimes with added securing methods like set screws or adhesives for high-load applications.

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.

Key Pins