American Machinist

A user's primer to modern dielectric oils.

A user's primer to modern dielectric oils

DIELECTRIC OILS ARE probably the least understood and most over-looked facet of electrical discharge machining (EDM). This may be because the dielectric oils are the smallest cost factor in operating an expensive machine. Managers understandably focus on higher cost items first. Yet in doing so, they may be making a crucial mistake. Dielectric oils are the bloodstream of the machine. If they fail, the machine fails--a classic cade of "penny wise, pound foolish.," EDM machines have radically changed since their introduction. So have EDM oils. This guide should help you select the right dielectric oil for your EDM operations.

Dielectric oil plays a crucial role in the EDM process. EDM uses the power of electrical sparks to shape the workpiece. Each sparks melts or vaporizes a tiny bit of the workpiece with intense heat. The refuse is swept away by the EDM fluid.

EDM is used for machining ceramics, high-hardness metals (hardened steel, tungsten carbide, Inconel, high speed steel), or other materials that are difficult to machine by conventional means. It iss often the only practical way to machine "exotic" materials used in the semiconductor and aerospace industries.

Sophisticated controls allow EDM to reproduce any pattern automatically, with accurate repeatability. EDM is also good for cutting intricate shapes and is especially useful for mold-making and die-sinking. In the past, many dies had to be machined in halves, then laminated together. EDM can cut them out of solid steel, making a stronger die or mold.

Purposes of dielectric fluid

You do not have to know much about how EDM works to run the machine. …

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