China Stud Bolt Manufacturer introduces the acceptance test of rivet nuts:

1. Quenching cracks

1. Appearance characteristics: The cracks are cross-cut by the crystal grains or along the grain boundaries, and obvious cracking marks will be produced along the foreign impurities. The cracks are generally caused by heat treatment or forging or other overstress in the forming process. The objects are re-applied, and the heat treatment cracks are often discolored due to rust spots.

2. Allowable limit: cracks of any degree (depth, length) and location are not allowed.


2. Forging cracks and impurity cracks

1. Appearance characteristics: due to forging or cutting off the blank, forging cracks are generated on the top surface and edge corners of the nut head. Impurity cracks are caused by metal impurities or foreign objects in the firmware originally existing in the material. Typical forging crack impurity crack type.

2. Allowable limit: If there are no more than two cracks from the hole to the edge, no crack from the hole to the first tooth, and the depth of the crack does not exceed 0.5 times the tooth height, and the width of the crack does not exceed 0.02D or 0.012IN, the screw Forging cracks and impurity cracks on the top and bottom of the cap are allowed.


Three, lock the cracks

1. Appearance characteristics: The locking end of the pressure riveting nut is produced by compression during the forming process. The cracks often appear in the vicinity of the locking end, and there may also be typical locking end cracks at the inner or outer edge.

2. Allowable limit: the locking cracks on the outer surface of the pressure riveting nut, if the nut can pass the torsion test. Yes, if the nut can pass the torque test.

Through the above introduction, China Bolts Factory hopes that you can simply refer to the content of this article in future use.

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