Stainless Steel External Circlip

Choosing the Right External Circlip
1) What is an external circlip & when to use it?

An external circlip is a C-shaped spring steel ring that fits into a groove on a shaft and prevents components from sliding off along the shaft.

Use an external circlip when you need a simple axial retainer instead of a nut/shoulder:

To locate bearings, bushes, gears, sprockets, pulleys on a shaft

To stop collars, washers or spacers from moving axially

When you want a compact, low-cost axial stop without machining large shoulders

Most industrial external circlips follow DIN 471 / ISO 8748 style (for shafts).

2) Shaft diameter & standard (DIN 471)

The first selection is always the shaft size:

External circlips are specified by shaft diameter (e.g. “External Circlip for 20 mm shaft – DIN 471”).

The circlip is designed to compress into the groove on that shaft size with correct preload and retaining force.

Simple rule:

Check your shaft nominal diameter (e.g. 15, 20, 25 mm).

Choose “External Circlip for Ø… mm shaft – DIN 471” to match.

Never force a circlip intended for a different shaft size – it will either be loose or overstressed.

3) Groove design – fit & retention

The shaft groove is just as important as the circlip:

Groove diameter & width must follow the corresponding standard (e.g. DIN 471 groove tables).

The groove defines:

Axial holding capacity (how much thrust load it can take)

How much the circlip protrudes beyond the shaft diameter to act as a shoulder.

Key points:

Groove must be machined accurately and free from burrs.

Depth must be sufficient so that the circlip sits properly while still projecting enough to retain the component.

For high loads or high speed, follow standard groove dimensions exactly – don’t improvise.

Avoid twisting or bending across the plane – this can distort the ring.

Mechanical Properties (Guide) – External Circlips

External circlips are spring elements, not simple rings.
They rely on elastic deformation to snap into the groove and provide a constant radial preload and axial retaining force.

Standard Carbon Spring Steel External Circlips

Base material: high-carbon or alloy spring steel, heat-treated.

Characteristics:

High elastic limit and good fatigue resistance.

Designed to open elastically during installation and return to original shape.

Hardened and tempered to a spring hardness range suitable for repeated flexing (typically in the mid-to-high Rockwell C range, exact value depends on manufacturer/standard).

Performance notes:

Provide reliable axial retention when used with correct groove size.

Suitable for a wide range of operating temperatures (approx. from sub-zero to moderately elevated temperatures, depending on material and finish).

Surface treatments (phosphate, oil, zinc, black oxide) offer basic corrosion and wear protection.

Stainless Steel External Circlips

Base material: stainless spring steel (specific grade varies by manufacturer).

Characteristics:

Good corrosion resistance in humid, marine and chemical environments.

Adequate spring properties for general retaining applications.

Slightly different modulus and yield vs carbon steels, but designed to meet comparable retaining performance for the given shaft size.

Performance notes:

Ideal where rust staining is not acceptable (food, pharma, marine, outdoor).

Used together with stainless shafts and components to maintain uniform corrosion resistance.