The product will inevitably be affected by the environment or other objects during transportation or use, resulting in partial functional failure of metal workpiece, such as oxidation, wear, corrosion, etc. Therefore, the quality of the coating layer has a vital influence on the surface performance of the product, and the quality of the coating can be effectively improved through the control of the coating quality. CTI China Testing can provide a series of tests for the coating of metal workpiece to help customers identify the quality of the coating and improve the service life of the product.