Connecting Pin

Movable Joint with a Locking Hole

 

Our connecting pin is designed for movable joints between two parts. One end has a head, while the other end features a small hole for a cotter pin, keeping the pin in place while allowing rotation. Common applications include car brake pedal assemblies, clutch rods, construction machine linkages, and farm tool hitch systems.

One of our clients manufactures brake systems for mining trucks. Their brake rod joint required a product that resists wear and stays securely in place. We designed a connecting pin with a cotter pin hole: the head was semi-round, and a hole was drilled at the tail. After assembly, the cotter pin locked it in position. Even under harsh mining conditions, the pin showed no wear or bending. This client has reordered from us for four consecutive years.

 

Our cold forming process complies with GB/T 6478-2015. The raw material carbon content ranges from 0.22% to 0.40%. We have a complete set of testing equipment, including a hardness tester, salt spray chamber, and tensile machine, ensuring every batch meets automotive industry standards.

products are available in diameters from φ3 to 10 mm and lengths from 4 to 40 mm. Materials include 10B21, ML08AL, 35# steel, 45# steel, SUS304, SUS430, and others. Surface finishes include zinc, nickel, chrome, Dacromet, phosphating, passivation, and blackening. Head shapes can be semi-round, cylindrical, or hexagon. The cotter hole diameter is 0.3 to 0.5 times the pin diameter and is located 2 to 5 mm from the tail. Tensile strength is ≥800 MPa for grade 8.8 and ≥1040 MPa for grade 10.9. Hardness ranges from HRC22–32 for grade 8.8 and HRC32–39 for grade 10.9.

Can we provide a prototype? Yes. You can send a used part or a 3D drawing. We reverse-engineer it, analyze the process, and quickly produce a sample for your testing.

Which cold forging standards do we follow? GB/T 6478-2015, GB/T 18146-2008, and GB/T 3098.1-2024. Cold forging steel grades include ML25, ML35, and ML40Cr. Outer diameter tolerance is IT9, length tolerance ±0.10 mm, and surface roughness ≤Ra5 μm.

How do we ensure no cracks? We use a metallurgical microscope to regularly inspect the metal flow lines. The head must exhibit complete flow lines after cold forming-this is our quality red line. We work with SAIC, Geely, and Chery, meeting all their stringent quality requirements.

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