| Grinding is gaining importance as a manufacturing technique; particularly for complex parts in the automotive and aviation industries. The technology hinges on super-abrasive grinding wheels that consist of a single diamond or cubic boron nitride layer bonded to the wheel surface. Electroplating is the process of choice for binding the abrasive layer in high-end applications. The production of plated super-abrasive grinding wheels depends on accurately controlling the current distribution during the manufacture of the grinding wheels.; The plating process consists of two distinct operations, both of which were modeled. The first, the 'tack-down' process, consists of electroplating a thin metal layer, ≈15 mum, onto the grinding wheel surface to temporarily attach abrasive particles to the wheel surface. The second, the 'over-plate' step, consists of plating a thick metal layer, 60--200 mum, onto the grinding wheel surface to mechanically bond the abrasive particles to the wheel surface.; The effects of the dense abrasive slurry used in the 'tack-down' step have been experimentally measured. The abrasive slurry decreased the solution conductivity of the nickel Watts bath from 0.11 S/cm to 0.022 S/cm and a thin, highly resistive layer formed near the cathode surface due to H2 gas bubbles becoming trapped in the abrasive slurry. The anode and cathode kinetics (io, alphaa, and alpha c,) were very stable during the tack-down process.; Variations of electrode kinetics with position along the wheel and the effects of the abrasive layer during the 'overplate' step were studied. The additive flux to different geometric features resulted in "peaks" having a 4% lower current density than "flat surfaces" and "valleys" having a 4% higher current density than "flat surfaces". The abrasive particle layer increased the plating rate by 220%, but did not significantly affect the current distribution.; A new and advantageous 'tack-down' process for the adhering of a single layer of super-abrasive particles to the grinding wheel prior to plating was developed. The new process involved development of a new adhesive, optimizing the curing steps for the adhesive, and development of a new copper tack-down bath. The process has undergone preliminary testing and has passed the initial grinding tests. |
