The ability of an EDM electrode to produce and maintain details is a crucial part of the machining process, and that ability is affected by its wear resistance, particularly when intricate details or thin, deep ribs are involved. To achieve maximum EDM productivity, moldmakers need technology that allows them to reduce electrode erosion/wear, ideally by distributing the wear among multiple part cavities. Wear partitioning functionality in a sinker EDM generator can help.

In a typical sinker EDM operation, machining progresses according to a group of settings from the first mold cavity all the way to the last cavity, and then starts again on the first cavity with the next group of settings, and so on. The shapes of the cavities negatively change due to electrode wear between the first mold cavity and the last.

Wear partitioning offers an alternative for electrode wear compensation. It optimizes the use of electrodes, sharing the electrode wear among the mold cavities to increase part quality and dimensional consistency. And while actual burn times remain unchanged, this function can help reduce the use of consumables. This is especially beneficial when electrodes are complex and require a lot of machining time to produce.

Wear partitioning allows machining to occur setting by individual setting. The EDM determines this alternative setting distribution, as well as what electrode will be used when and in what sequence. It also indicates where machining should start in the cavities, when to switch the electrodes in and out, and what orbits to use with which electrode and for how long.

For example, a sinker EDM using this functionality can decide to enter the first cavity and orbit material out with the first electrode, then progress to the second and third finishing electrodes. Or it may rough out all the cavities with a roughing electrode, going from right to left, for instance, then switch to the semifinishing or finishing electrodes, moving back from left to right. Rough-cutting in one direction and semifinishing in the other in such a fashion eliminates wasted machine movement and helps shorten part cycle times.

Wear partitioning is only possible with fully digital EDM generator technology, however. The prerequisites for using it are that the mold cavities be equivalent in terms of depth, surface finish and required dimensional tolerances.

The three functionalities of fully digital EDM generators that have been described here can help mold shops optimize their operations in a range of different ways and thereby give themselves a leg up on their competition.