EDM (Electrical Discharge Machining)

It goes without saying that the heart of manufacturing is innovation. From the cotton gin to the steam engine to the assembly line to the CNC, the manufacturing process is always being reinvented, refined and reimagined. Today, a lot of the talk is about additive manufacturing, and justifiably so. Since its dawn in the 1980s, AM has moved from a "that's neat" tool for hobbyists to a valued tool for prototypers to making fixtures and long part runs.

While many machine shops have an EDM, they still have to decide when it makes sense to outsource certain jobs.

Omega Manufacturing specializes in challenging wire EDM work, but also offers one-stop parts manufacturing.

New technology has reduced the footprints of sinker EDMs and made them smarter, faster and more efficient.

A second Look Ahead item features a micromachine that performs up to seven machining operations.

The spark gap is the physical distance the electric current has to jump off the wire to burn the workpiece when wire EDMing. Controlling the spark gap is critical to achieving required part dimensions and surface finishes. Variables that impact the spark gap include the workpiece material and thickness, wire diameter and type, and part tolerance and surface finish requirements.r The wire EDM process is physically unstable because of the constant advancement and retraction of the axes. "Wire EDMing does not have or function with a set feed rate like a milling operation," said Brian Pfluger, EDM product manager for Makino Inc. at the company's Auburn Hills, Mich., facility. Wire EDMing requires a combination of small mechanical and, especially, electrical changes to occur thousands of times per second to be stable and consistent, he added. Makino is headquartered in Mason, Ohio.

Wire EDMing requires a range of equipment and complex operations, which can lead to a variety of problems. But the capability and flexibility of the electrical adaptive control technologies that monitor the EDM process—such as flushing, wire tension, automatic wire threading, wire consumption levels, geometry control, surface quality, water resistivity level and water chiller/thermal stability—have greatly improved over the past 10 years.

The CTE editorial staff offers a machine tool product review.

The Look Ahead feature in the May 2012 issue of Cutting Tool Engineering includes a linear cylindrical drive technology for wire EDMs.