The potential of plating techniques in the development of rapid EDM tooling

Abstract

Electrodischarge machining (EDM) is a widely used process in the manufacturing of mould cavities for plastic products. EDM work typically accounts for a large portion of overall production time. A major cost and time element of EDM is electrode production, which can account for more than 50% of the total machining costs. A large complex electrode profile, which is very difficult to produce through machining and is also time consuming, can be easily produced using the rapid prototyping (RP) technique. The direct laser sintering of metal powders is a widely established RP process that can be employed for the rapid production of EDM electrodes. In this study, the above-mentioned technique has been employed. The powder mixture used in this process consists of copper, tin, nickel and phosphorus. An infra-red (IR) 200 W CO2 laser is used to sinter the powdered metals layer-by-layer in order to form solid electrodes. Electroless copper and copper plating are then employed to improve the surface finishing and the conductivity of the sintered electrode as it deposits a uniform thickness of metal onto the substrate by chemical reaction, without building up at the edges and corners, and achieves unique physical characteristics. The performance of the newly developed electrode is very similar to that of conventional copper electrodes. It is found that integration of RP and electroless plating techniques can be a potential means of the rapid production of EDM electrodes at low cost.