Thread Tolerance Control and Go-No-Go Gauge Acceptance Standard for Mini Screws

Thread dimension accuracy determines assembly performance of micro screws. Out-of-tolerance thread causes difficult insertion or insufficient clamping force in electronic assembly.

1. Common Size Tolerance Range

List standard pitch diameter tolerance for mainstream sizes including M1.0, M1.2 and M1.4 according to international 6g tolerance class.

2. Gauge Inspection Rule

Go gauge shall fully screw in by self-weight; no more than two threads allowed for no-go gauge screwing in. Increase sampling rate for medical precision screws.

3. Assembly Defect from Abnormal Tolerance

Oversized thread cracks plastic housing; undersized thread leads to loose connection after long-term vibration.

4. Production Control

Check thread dimension every four hours during mass production and replace worn thread rolling dies timely.