||Pneumatic components product actuators, cylinders and mechanical clamps in the clamping and positioning of the moving process, often produce two parts of the friction between the phenomenon of friction and then produce the workpiece wear problems, will make the product lost precision positioning and clamping Function, so the type of wear behavior for the adhesion and abrasive mechanism to determine the analysis, and then the choice of high friction parts and its heat treatment or surface treatment relative to the important, nitriding in a large number of mold applications and automation industry Is very common, but for the surface nitriding after the wear test conditions to change the different contact pressure and different speed pairs are rarely discussed, this study explored by the special Thai special steel KDA1 steel, hot work die steel SKD61 do nitrogen (Gas nitriding, soft nitriding (with or without white layer)) by different contact pressures and different rotational speeds on the structural changes and properties of the surface nitriding layer. The effects of different nitrogen The surface structure and depth of nitriding, XRD surface structure analysis, gas nitriding conditions for the organization of Fe3N, Fe4N, soft nitriding The microstructures were Fe2N, the microhardness measured the depth of nitriding hardening curve, EPMA confirmed the qualitative analysis of nitriding treatment, three different contact pressures and three different speed of the wear test and electron microscopy observation of wear surface, the experimental results show KDA1 nitriding depth and Wear resistance than SKD61 good, gas nitriding and soft nitriding (with white layer) treatment due to compound white layer peeling and diffusion layer abrasive wear loss weight is the most, soft nitriding treatment will add carbon atoms, inhibit the organization Fe3N , Fe4N, the compound layer is Fe2N, and the toughness is better. This organization is easy to produce adhesive wear when grinding. In addition, the nitriding test piece and the aluminum alloy are different from the hardness due to the hardness of the grinding wheel. The film on the film to produce adhesive wear, a white layer of compounds on the nitriding test piece of aluminum alloy adhesion phenomenon less test pieces and the loss of weight on the grinding wheel for the least, but the compound white layer peeling with the substrate will produce abrasive wear, the test piece loss Weight increased significantly.