WHY USE EDM?

Why EDM?
There are many reasons to use EDM over conventional approaches. Below are some common examples of how the creative use of EDM can solve difficult problems and save time and money:

Design Freedom
EDM, both Wire and Sinker type, provides a degree of design freedom unattainable with conventional machining processes, which employ a rotating tool or workpiece. Almost any conceivable three-dimensional shape can be created quickly, accurately, and repeatedly with EDM. A simple example is a blind, square hole with sharp internal corners.

Problem-Solving Tool
Many design and manufacturing problems can be overcome through the creative use of EDM. Parts that are “headaches” to machine conventionally become routine with the help of EDM. Small internal corner radii, long reaches, complex shapes, and fine details can all be readily produced.

Close Tolerances
Both Sinker and Wire EDM are capable of holding very close tolerances, down to +/-.0001 inch. In addition, they are capable of very good geometric accuracies, such as flatness, parallelism, and squareness, due to the absence of any forces between the electrode and the workpiece, which would cause deflection in conventional machining.

Reliability
EDM is a very reliable and consistent process. It is often used for difficult features on very costly parts to minimize the risk of loss. There is no possibility of broken drills or taps to cause the parts to become scrap.

Hardened and Exotic Materials
The hardness of the workpiece is of no significance for EDM. Hardened tool steels and stainless steels, along with carbides, can be EDM’ed as easily as soft materials. Exotic, difficult to machine alloys such as Inconel and Hastelloy are also easily cut by EDM. In fact, EDM can be used with any electrically conductive material.

Thin or Fragile parts
There is no physical contact between the electrode and the workpiece. Unlike tradition machining processes where the cutting tool must generate physical pressure to cut, EDM utilizes the heat of tiny electrical sparks to slowly and precisely erode the workpiece. In addition, only minimal clamping forces are required to hold the part for EDM, minimizing the possibilities of damage and distortion.

Inaccessible Features
Inaccessible features, such as cross connections between bores, or features cut sideways at the bottom of deep, blind cavities, can be readily produced without having to enter externally and plugging afterwards. The electrode can be mounted on an arbor, which is then manipulated into position inside the workpiece, and then the feature can be cut in any direction. In especially tight quarters, a through-feature can be EDM’ed from both directions to meet in the middle. In many cases, EDM is the only way these types of features can be produced.

Small Features
Small details are readily machined by EDM to close tolerances. In fact, since the cost of EDM is directly related to the volume of material to be removed, small features can be surprisingly inexpensive to produce by EDM. EDM also lends itself to massively parallel processing of small features, further reducing cost.

Avoid Heat-Treatment Distortion
The ability to EDM hardened parts permits the finishing of critical, close tolerance features after heat treatment, whereas conventional approaches require those features to be finished prior to heat treatment, subjecting them to the uncertainties of size change and distortion.

Rework & Salvage
EDM is often used to repair and salvage parts. For example, it can be used to remove broken taps and drills. Also, missing threads can be added to hardened parts. Subtle changes and modifications are also easily done by EDM that would be difficult or impossible by other means.