According to the production of countersunk self tapping screws samples

June 10, 2019, the countersunk self tapping screws manufacturer Shi Shi Tong Metal Products Co., Ltd. received samples from Australia. It is a black countersunk hexagon self-tapping screw.

From the appearance, there is no difference from our common countersunk self tapping screws. We tested the customer’s sample data and found that this was a UNC countersunk self-tapping screw rather than a metric countersunk screw in China.

As the customer said it was easy to slide and break the head. We tested the strength of the screw, and found that the sample sent from the customer was not subjected to hardening heat treatment After we asked about the customer’s request for strength, the final customer decided to add a hard to 6.8 grade. The pre-load torque corresponding to the 6.8 level was 674.3-732.7N and the received torque was 0.23-0.28 Nm.

June 16, these countersunk self tapping screws have been shipped. June 22, Australian customers said they received our screws, and are very satisfied with our products, looking forward to more orders in the future.