All About Spring Pins｜A Practical Fastener That Locks by Elasticity
- 翰君 陳
- Aug 27
- 2 min read
In many machines and structures, a spring pin is a fastener that relies on its own elasticity to fasten and locate parts.It is typically a slotted, cylindrical pin that expands against the hole after insertion, creating a tight fit that prevents loosening.
This property lets spring pins both withstand shear and absorb vibration, making them an indispensable “invisible guardian” in many systems.
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How to Determine the Right Spec？
When selecting a spring pin, the key is whether it matches the hole size and meets the application needs.
Hole pairing
A spring pin’s nominal diameter is usually slightly larger than the hole so that compression during insertion generates holding force.Example: For a Ø5 mm hole, a Ø5.5 mm spring pin is appropriate.
Quote example we offer: Spring pin 3 × 20. Before installation, the actual outside diameter is 3.15–3.25 mm, intended for a Ø3.0 mm hole.Please tell us your hole diameter and length requirements.
Length selection
Choose a pin length greater than the total thickness of the parts being secured so both ends are properly supported.
Material considerations
Carbon steel (heat-treated) – General use, durable and economical; suitable for high-load cases
Stainless steel SUS304 / SUS316 – Corrosion-resistant; ideal for food, outdoor, or humid environments
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Don’t Miss These Pre-Purchase Details
Before ordering, confirm:
Hole tolerance meets the relevant standards (e.g., JIS B 2808, ISO 8752)
Material fits the environment (avoid rust or premature wear)
Length adequately covers the stack thickness of components
Spare quantity for maintenance (spring pins are often not reused)
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How to Install a Spring Pin Correctly
Installation is simple, but details affect service life:
Align with the hole – Keep the slot aligned to the hole and maintain perpendicularity.
Press to seat – Use a hammer or installation tool to drive evenly; avoid striking with sharp points.
Confirm seating – The pin should be flush with or slightly proud of the surface, without wobble.
Tips
For large sizes or deep holes, use a fixture/tool to avoid tilt.
Spring pins are generally not recommended for reuse; replace after removal.
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Where You’ll See Spring Pins
Locating transmission components (gears, bushings)
Hinges and joint connections
Automotive and motorcycle fastening points
Limit/anti-loosening structures in automation equipment
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Why Choose Sheng Fong Precision?
Sizing is only part of the decision—quality and supply reliability matter too. Sheng Fong Precision offers:
Complete range – Both standard and special sizes available
Material options – Carbon steel, stainless steel, heat-treated versions for different needs
Strict QC – Each lot inspected for dimensions and appearance to ensure stability
Fast shipping – Stocked items; rush and small-lot orders supported
Professional support – Selection and installation advice to reduce risk
With Sheng Fong’s expertise, your machinery can run longer and more stably.
--- Full specification and size list: https://lihi3.me/jTywm
📩 Contact us for spring-pin selection via LINE (ID: @s9000)
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