Internal vs. External Circlips: How to Choose the Right Retaining Ring

A circlip — also called a retaining ring or snap ring — is a small, simple part with an important job: it sits in a groove and stops a component from sliding off a shaft or out of a bore. Get the right one and your assembly holds together for the life of the machine. Get the wrong type, size, or material, and parts work loose, fret, or won’t fit at all. After 20 years stamping circlips and retaining rings for automotive, industrial, and medical customers, here’s how to choose correctly.

What a circlip does

A circlip is a spring-tempered ring that snaps into a machined groove and expands or contracts to grip it, creating a shoulder that prevents axial (lengthwise) movement. The two fundamental families are defined by where that groove is:

• External circlips fit a groove on the outside of a shaft.
• Internal circlips fit a groove on the inside of a bore or housing.

That single distinction — shaft or bore — is the first and most important choice you’ll make.

Internal vs. external at a glance

If you remember nothing else: external rings squeeze a shaft; internal rings push out against a bore.

The main types of retaining rings

• Tapered-section circlips (DIN 471 / 472) — the classic circlip with lug holes for pliers; tapers in width so it sits concentric in the groove. The workhorse for most shaft and bore applications.
• E-clips (DIN 6799) — push on radially (from the side) onto a grooved small shaft; fast to install, ideal for high-volume light-duty assemblies.
• C-clips / C-rings — heavier, axially-installed rings for higher thrust loads where a tapered circlip isn’t strong enough.
• Constant-section rings — uniform cross-section for applications that prefer uniform contact.
• Custom snap rings — non-standard diameters, thicknesses, or materials made to your drawing.

How to choose the right circlip

Work through these five questions — they’re exactly what our engineers confirm on every circlip order:

1. Shaft or bore? On a shaft → external (DIN 471). Inside a housing → internal (DIN 472). This sets the family.
2. What are the groove dimensions? Groove diameter, width, and position determine the ring size and thickness. Give us the shaft/bore diameter and we’ll recommend the standard groove and ring.
3. How much thrust load? Light, high-volume duty → E-clip. Higher axial loads → tapered circlip or C-clip.
4. What’s the environment? Corrosion or washdown → stainless steel. Dry indoor → carbon/spring steel with a protective finish.
5. What standard or tolerance applies? DIN, ISO 3056, JIS B2804, or a custom drawing — plus any clamping-force or dimensional tolerance that’s critical.

Material and finish

• Carbon / spring steel (65Mn) — economical, strong clamping force; needs a finish for corrosion resistance.
• Stainless steel (304 / 316) — corrosion resistance for medical, marine, food, and outdoor use.
• Phosphor bronze / brass — for non-magnetic or conductive needs.

Common finishes include zinc plating, nickel plating, black oxide, passivation, and chrome plating — chosen to match the operating environment.

Common circlip mistakes to avoid

• Confusing internal and external. An external ring won’t work in a bore, and vice versa. Always specify shaft vs. bore.
• Ignoring the groove spec. A ring is only as good as the groove it sits in; the groove must match the ring standard.
• Under-rating the thrust load. A light E-clip in a high-thrust joint can dish out or pop free.
• Wrong material for the environment. Carbon-steel rings rust in humid settings — specify stainless where it matters.
• Inconsistent quality between batches. Variation in clamping force or thickness causes intermittent failures. Insist on 100% inspection and batch traceability — this consistency separates a reliable supplier from a cheap one.

Get the right circlip for your assembly

Whether you need a standard DIN ring or a fully custom snap ring, send us your shaft or bore diameter, groove details (if known), load, material, and quantity — or a sample to match. Our engineers will recommend the right retaining ring and quote it fast.

• Browse our custom circlips and retaining rings
• See how our spring design and engineering support works
• Or send your drawing and get a fast quote

GL Springs (Shanghai Guanglei Spring Co., Ltd.) is an IATF 16949–certified manufacturer of custom springs, circlips, and wire forms in Shanghai, China, supplying internal and external retaining rings to DIN, ISO, and JIS standards for OEMs worldwide since 2005.