Rapid prototyping of zirconium diboride/copper electrical discharge machining electrodes.

摘要

The acceptance of rapid prototyping (RP) as the predominant technique for producing polymer and paper parts directly from computer-aided design (CAD) models has led many corporations and universities to try to extend its capabilities to more robust materials. In addition to producing prototype metal and ceramic parts, a significant effort has been made to create parts that are useful as tools and dies or that reduce the time necessary to create tools and dies. Most materials used for tools and dies are very hard, because they need to be able to withstand millions of cycles before failing. Electrical discharge machining (EDM) is the most common method used to machine tools and dies out of hard materials. A method for producing EDM electrodes using RP could greatly reduce the time and cost involved in creating tools and dies.; A new EDM electrode material made up of zirconium diboride and copper (ZrB{dollar}sb2{dollar}/Cu) that is superior to traditional EDM electrodes has been investigated. The processing techniques necessary for creating Zr{dollar}sb2{dollar}/Cu electrodes from powders of ZrB2 and copper have been developed. These ZrB{dollar}sb2{dollar}/Cu electrodes have a better wear ratio and a faster sink rate than graphite, copper or tungsten/copper EDM electrodes. Performance variables that were tracked are: (1) wear ratio, (2) sink rate and (3) surface finish, where ZrB{dollar}sb2{dollar}/Cu, copper, graphite and W/Cu were used as anodes (electrodes) and stainless steel as cathodes (workpieces). The ZrB{dollar}sb2{dollar}/Cu electrode material system retains its superior EDM electrode performance across a number of materials processing and compositional variations. Scanning electron microscopy (SEM) was used to study the electrodes after EDM. These SEM observations facilitated an understanding of the superior EDM electrode performance characteristics of ZrB{dollar}sb2{dollar}/Cu to traditional EDM electrode material systems.; A method for creating geometrically-complex ZrB{dollar}sb2{dollar}/Cu EDM electrodes using the selective laser sintering (SLS) RP technique was developed. Polymer coated ZrB{dollar}sb2{dollar} powders are processed in a SLS machine to produce the desired geometry. Subsequent polymer burnout, sintering of the ZrB{dollar}sb2{dollar} and copper infiltration are performed in a high-temperature furnace.