Stainless Steel Internal Circlip

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

An internal circlip is a C-shaped spring steel ring that fits into a groove inside a bore or housing.
It acts as an axial retainer to stop components from moving out of a bore.

Use an internal circlip when you need to retain parts inside a housing, such as:

Bearings, bushes, seals inside a housing or hub

Gears, sprockets, pulleys within a recess

Spacers, washers, or sleeves located axially inside a bore

Most industrial internal circlips follow DIN 472 (internal circlips for bores).

2) Bore diameter & standard (DIN 472)

The first selection is always the bore (housing) diameter:

Internal circlips are specified by bore diameter, e.g.:

“Internal Circlip for Ø40 mm bore – DIN 472”

The circlip is designed to expand into the groove for that bore size and provide the correct radial preload and axial retaining force.

Simple rule:

Find your bore diameter (e.g. 20, 30, 40, 80 mm).

Choose “Internal Circlip for Ø… mm bore – DIN 472” in the required material.

Never mix sizes – a wrong circlip will either sit loose or be overstressed.

3) Groove design inside the bore

The housing groove is critical to performance:

Groove diameter, width and flank angle are defined in DIN 472 (or matching standard).

The groove must be machined accurately so the circlip:

Seats fully in the groove

Projects inward enough to act as a shoulder and retain the component

Key points:

Groove must be free from burrs and sharp edges.

Depth must allow the circlip to sit flush enough while still having sufficient radial projection to hold the retained part.

For high loads/speeds, follow groove dimensions exactly as per standard or drawing.

4) Material & corrosion resistance

Internal circlips are commonly available in:

Carbon spring steel (standard)

The most widely used option

Usually supplied phosphated, blackened, oiled, or lightly zinc-coated

Suitable for gearboxes, automotive, machinery where environment is dry or lubricated

Stainless spring steel

For humid, marine, food, chemical, and wash-down environments

Used with stainless housings and components

Provides better long-term corrosion resistance than carbon steel circlips

Selection guide:

Inside sealed, oily or protected housings → Carbon spring steel internal circlip is usually adequate.

In corrosive, wet, or sanitary environments → Stainless internal circlip is preferred.

Stainless Steel Internal Circlips

Material: stainless spring steel (grade depends on manufacturer – often a martensitic or austenitic stainless selected for spring properties).

Properties:

Good corrosion resistance in humid, marine, and wash-down environments

Adequate spring behaviour for retaining tasks

Slightly different modulus and yield compared to carbon steel, but designed to give comparable retaining force for the specified bore size

Performance notes:

Ideal when:

Rust staining is unacceptable

Equipment is regularly subjected to cleaning fluids, saltwater, or chemicals

Best used with stainless housings/components for consistent corrosion performance.