7 Situations Where EDM Is Better Than Conventional Machining

Electrospark machining (EDM) is one of the most common machining methods used by machinists. Instead of using sharp cutting tools, this process uses sparks to cut through materials. This article will introduce seven specific situations where EDM may be better than traditional machining to help machinists make better choices.

1.What is EDM?

EDM is one of the common processing methods used by machinists. It does not use sharp cutting tools, but uses sparks to cut materials. During the processing, the soft metal or graphite tool and the conductive metal workpiece act as two electrodes. When both are immersed in a dielectric fluid and a voltage is applied, the liquid dielectric decomposes to generate an arc, thereby removing material from the workpiece, and the debris is washed away by replacing the liquid dielectric.

2.EDM Type

There are two main types:
1.One uses a metal mold as an electrode, which is suitable for creating complex shapes;
2.The other is wire cutting, which uses a taut wire and is suitable for cutting thick plates and particularly hard metals.

3.Compared with traditional processing

Compared with traditional machining, it has many advantages, such as being able to penetrate very hard metals, process complex shapes, and reduce distortion of fine features.
However, it also has its limitations. It is not suitable for plastic processing and the processing speed is slower than traditional processing. In most cases, CNC has more advantages.

4.When EDM is better than conventional machining

①When sharp internal corners are required

Traditional CNC machines leave rounded corners on the workpiece because the cutting tools are usually round, but wire EDM wire is much thinner than CNC cutting tools, allowing for almost square internal corners with corner radii as small as 0.005 inches.

②When very deep cuts are required

Traditional CNC machine tools require long cutting tools to make deep cuts and cavities, which can cause chatter and result in poor quality machining. EDM is less prone to chatter and can easily machine holes with length-to-diameter ratios of up to 20:1, and even 100:1 in some cases.

③When the workpiece material is very hard

EDM is not affected by the hardness of the metal and can meet tight tolerance requirements. It can also process metals such as Hastelloy, Titanium and Inconel.

④When a part requires a mirror finish

EDM typically produces a pitted or dimpled surface, but by tightly controlling parameters or introducing fine abrasive powders into the dielectric fluid, it can produce an excellent mirror finish of approximately 5 RMS (4 microinches Ra) without the directional “layers” of conventional machining.

⑤24/7 Production

EDM has advantages in automation and unattended manufacturing. More predictable and less susceptible to error interruptions than traditional machining, it can be automated and run 24/7, allowing manufacturers to create efficient, automated manufacturing workflows.

⑥When tight tolerances are required

Very tight tolerances can be achieved without distortion of the workpiece. Through multiple passes, tolerances as low as +/- 0.0002” can be achieved, but cutting speeds must be reduced to ensure maximum accuracy.