The Technology Research Of CNC Electric Plating

Brush plating is regarded as the technology of high speed electroplating, which has been widely applied in worn surface repairment、surface modification and so on. Due to manual, however, some disadvantages of the traditional technique also exist, such as low efficiency, labor-intensive and instability of coating quality and so on. To a great extent, its further application and development may be restricted by the above drawbacks. The CNC technology combining with the traditional brush plating can be used to work out the problems effectively. Plating solution (Ni-P alloy solution) with high concentrations in certain flow velocity is circularly flowed in the small electroplating space of the anode and cathode, trajectory being controlled with motion controller and fine-grain coatings being got on the cathode workpiece surface. In this paper, the numerical control plating experimental set-up was developed and some experiments were finished on the experimental set-up.Firstly, the basic theories of CNC electric plating and the methods of improving limiting current density were analyzed. The electrical field model were established and analyzed with the finite element method. It was found that the current density distribution of cathode surface was two peaks clipping a trough.The peaks appeared in the physical center of the unilateral and the trough appeared in the jet center. Far from the area of the anode tools, cathode current density decreased rapidly. This provided theoretical guidance for the follow-up basal experiments.Secondly, numerical control electric plating experimental set-up was built.The system of electroplating solution、the anode and the fixture were designed.The factors affecting the coating surface roughness、coating hardness and coating deposition rate were examined with the single factor and orthogonal tests. The optimized results of orthogonal tests were obtained with the roughness0.092μm、the max hardness280.63HV and the deposition rate23.3μm/min. The binding force of coating was tested with the thermal shock method and the better results were got.The heat treatments on200℃and400℃were done and the results showed that hardness was significantly increased separately over55.34%and120.19%. Finally, the electric plating of the spur gear surface was studied. The precision molding and coating quality were mainly analyzed.The results showed CNC electric plating had a better forming precision. The average roughness was0.433μm and with the simple heat treatment, the work surface which could meet the requirements was got.