Current page:

Home

/

News

/

What is the procedure for the fine thread self tapping screws inspection and determination?

News

Contact Us

Tel:

+86 13143444311

Email:sst@szsst88.com

Fax:+0086-755-27322278

Address:Building 9, First Industrial Zone, Tantou Industrial City, Songgang Street, Baoan District, Shenzhen 518105, Guangdong, China

What is the procedure for the fine thread self tapping screws inspection and determination?

The inspection of the fine thread self tapping screws generally has two types: destructive inspection and non-destructive inspection.

fine thread self tapping screws

Non-destructive inspection: Randomly take samples from the acceptance batch according to the requirements in the table, perform visual inspection or other non-destructive inspection, such as using magnetic technology or eddy current. If the defective sample is found not to exceed the permissible limit, the batch is accepted. If the number of defective samples is found to exceed the allowable limit, the destructive inspection is performed in batches with these defective products.

fine thread self tapping screws

Sample size for visual and non-destructive inspection

Batch (N) Sample size (n)
N≤1200 20
1201≤N≤10000 32
10001≤N≤35000 50
35001≤N≤150000 80

Note: 1. Batch refers to the same type, specification and performance level, and the number of fine thread self tapping screws submitted for acceptance at the same time.

  1. The sample size is based on the inspection level S-4 specified in Table 10 of GB/T 15239.

 

Destructive inspection: After non-destructive inspection, if a non-conforming product is inspected, the product with the most serious defects is composed of the second sample according to the provisions in the table, and a defect perpendicular to the defect is taken at the maximum depth of the defect. The section is checked.

Second sample size for destructive inspection

The number of defective products in the sample (N) Sample size (n)
N≤8 2
9≤N≤15 3
16≤N≤25 5
26≤N≤50 8
51≤N≤80 13

 

Note: The second sample size is specified in GB/T 2828.

stainless steel button head torx screws

Judgment: In the visual inspection, if any quench cracks on any part or wrinkles on the inner corners are found or wrinkles on the non-circular shoulder fasteners that are lower than the “three-leaf” shape on the support surface, Reject the batch.

In the destructive inspection, if there are forging cracks, bursts, cracks and streaks, dents, cuts, and damage that exceed the specified allowable limit, the fine thread self tapping screws are rejected.

 

If you want to customized fine thread self tapping screws, please send an email: annie.li@szsst88.com

12 月-22-2018

kalyn