Typical processing route of fasteners

Update:06-03-2020
Summary:

1. Small size bolts below 8.8 (M16 and below) Raw mater […]

1. Small size bolts below 8.8 (M16 and below)

Raw material selection: low carbon steel (Q235, 08, 10, 18, etc.)

Blank forming method: cold heading

Thread forming: rolling or thread rolling (selection method of rolling or thread rolling)

Routing:

Raw materials (selected materials) — material transformation — cold heading — turning (chamfering, flat end) — thread rolling or thread rolling — surface treatment (as required) — final inspection — packaging

2. Large bolts of 12.9 (M16 and above)

Raw material selection: medium carbon alloy carbon steel (35CrMo, 42CrMo, SCM435, etc.)

Blank forming method: Hung Hom

Thread forming: rolling

Routing:

Raw materials (selected materials) — material restructuring — blanking — turning processing (turning slabs) — Hung Hom — turning processing (turning head, chamfer, flat end, flat length, etc.) — (marking) — (shot blasting) — grinding Cutting (screw grinding)-rolling-dephosphorization-heat treatment-flaw detection-surface treatment-final inspection-packaging

3. Screw nut processing technology

Screw nuts made of red cymbals (large size)

Material selection (according to screw nut performance requirements)

Routing:

Material transformation—cutting—turning (mainly threaded bottom hole, flat end guaranteed height) — (marking) — tapping — (heat treatment) — surface treatment — final inspection — packaging

Material transformation—cutting—turning (mainly threaded bottom hole, flat end guaranteed height) — (marking) — (heat treatment) — tapping — surface treatment — final inspection — packaging

Whether the screw nut is heat treated depends on the mechanical properties of the nut.

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