Visual inspection and dimensional inspection requirements for fasteners


Visual inspection 1) Is the supplier identification and […]

Visual inspection

1) Is the supplier identification and performance level identification required?

a Bolts and screws with performance level ≥ 4.8 must be marked;

b Nuts with performance level ≥5 must be marked;

c Bolts, screws and nuts with a nominal diameter ≥ 5mm need to be marked.

d Bolts and screws with a nominal diameter ≥ 30mm must be marked with the production batch number

e Washers with a hardness of 300HV need to be marked (recommended)

2) Fastener appearance

The surface is clean, flat, no burrs, no rust spots, no missing teeth, rotten teeth, and the coating must not have defects such as bubbles and peeling, and the thickness of the coating meets standard requirements

Size inspection

Inspection according to relevant national standards or technical requirements (agreements, specifications, drawing requirements, etc.)

1. For bolts, screws, studs, and nuts, check the thread length, nominal thread diameter, head thickness, rod diameter, nut height, straightness, etc., and inspect using the corresponding thread pass gauges;

2. The bolts and screws before plating shall be tested with a ring gauge with a tolerance level of 6g, and the ring gauges shall be tested with 6h after plating;

3. Nuts with a tolerance grade of 6G shall be used for inspection before plating nuts, and 6H plug gauges shall be used for inspection after plating;

4. The general inspection requires that each thread can pass smoothly to be qualified, and the stop inspection can only pass at most 2 threads.