6：Surface 

6.1 Purpose：

Color according to appearance requirements ；

Increase the anti-corrosion ability of products ；

Control friction coefficient to stabilize product assembly force；

P.S.Due to the risk of hydrogen embrittlement during electroplating of high strength fasteners 10.9 and above, it is recommended to adopt dacromet/geomet coating uniformly. If electroplating must be used, rigorous heat treatment is required to dehydrogenate and reduce the risk of hydrogen embrittlement. 

6.2 Surface Process ：

Solvent degreasing -Mechanical shot -Coating -Drying -Coating -Drying -Check and confirm dry 

6.3 Outsourcing control ：

Since most manufacturers do not have the ability of surface treatment, all surface treatment is outsourced.Therefore, we will conduct annual audit for suppliers in accordance with the standard of CQI-11, and strictly require the management of suppliers,Operation, inspection, in order to achieve the purpose of high quality, efficient production. 

6.4 Test 

For outsourced products, the following key points should be controlled.

6.4.1 Coating Thickness

6.4.2 Salt Spray Test 

6.4.3 Coefficient of friction test