Metric Basic External Retaining Ring

For spring steel material Metric Basic External Retaining Ring, the common treatment methods include oxidation/brightening and phosphating. We will recommend appropriate surface treatments based on the working environment of different customers.

(1) Oxidation / Browning

Features：It’s cost efficient and used in most common scenarios. It forms a tight oxide layer on the surface, can prevent rust to a certain degree and also holds oil well. This treatment won’t change the dimension of the parts.

Applications：Suitable for regular indoor mechanical working conditions, including auto parts and general standard equipment.

Key points：The oxide coating is quite thin, so the rust protection effect is limited. Not recommended for outdoor use or places with strong corrosive substances.

（2）Phosphating

Features: Better rust prevention than blackening; forms porous phosphate film with strong oil storage capacity; does not change the size of the workpiece.

Applications: The phosphated Metric Basic External Retaining Ring is suitable for use in indoor or semi-outdoor environments where higher anti-rust requirements are needed.

Key point: Excellent performance as a coating base.

（3）Galvanization

Features：It relies on the sacrificial anode principle to protect parts from rust.

Applications：Not really suggested for spring steel retaining rings that bear regular force or dynamic load.

Key points：Galvanizing may lead to hydrogen embrittlement. For high-strength parts, this could easily cause cracking or breakage.

FAQ

（1）Will your surface treatment affect the size accuracy and mechanical properties of the Metric Basic External Retaining Ring?

All surface treatments are carried out after the heat treatment and hardness testing, thus they will not alter the mechanical properties of the spring steel itself.

（2）What are the special requirements for surface treatment in food machinery or medical equipment?

The food and pharmaceutical sectors need parts with non-toxic surfaces, good corrosion resistance, no peeling issues, and easy to clean.

We mainly suggest 304 or 316 stainless steel. Use the raw natural finish without any organic coating. This type can stand up to daily cleaning and regular disinfection work.

（3）How do you control the quality of the surface treatment? Could you provide a test report?

We implement the quality management system and conduct 100% inspection or batch sampling on the key indicators of surface treatment: visual inspection, salt spray test, etc.

We can provide material certificates, surface treatment process reports and salt spray test reports along with the goods.

（4）How many hours can your Metric Basic External Retaining Ring withstand in a salt spray test?

It all depends on what kind of surface treatment is used and whether oil is added.

Oxidation blackening: 24 to 48 hours

Phosphating: 48 to 72 hours

Dacromet: 96 to 500 hours

Raw 316 stainless steel: 1000 hours and above

We can pick the best surface treatment or material option according to the salt spray standard the customer needs.