The Ultimate Guide to Electrical Discharge Machining (EDM)

Traditional methods like manual milling, turning, and drilling often prove costly, inefficient and unsuitable for intricate designs when manufacturing requires complex dimensions, materials, and specifications. Advancements in technology, such as Computer Numerically Controlled (CNC) Machines, allow manufacturers to adhere to tight tolerances consistently. However, for some applications, component designs have narrow requirements and intricate features that even the best traditional CNC machines can’t meet.  This is where Electrical Discharge Machining (EDM) is a game-changer, achieving manufacturing goals when conventional machining reaches its limits. 

What is Electrical Discharge Machining (EDM)?

EDM is a subtractive manufacturing process that uses electrical discharges to shape materials. This heat-based method converts electrical energy into thermal energy, melting or vaporizing excess material from a workpiece. EDM can manipulate this material removal to create specific cuts and shapes, making it ideal for working with materials that exhibit good electrical conductivity, regardless of their hardness.

While EDM is not the fastest production method, it makes up for reduced speeds by allowing for precision designs with material removal thicknesses less than human hair. It excels at creating injection molding tools, sharp internal corners, curves, small holes, engravings and more.

What is the EDM Process?

Electrical Discharge Machining uses an electrode connected to a power supply. As the electrode approaches the workpiece, a spark is created, generating extreme temperatures that melt the material. The machine’s instructions are governed by a CNC program.

The high temperatures of EDM require the use of an insulating (dielectric) fluid. The electrode and the workpiece are immersed in the dielectric fluid for the duration of the process. By doing so, the fluid can control the electric spark, act as a coolant and remove any waste material created by the machining process.

This tightly controlled process produces complex geometries while minimizing stress on the workpiece and electrode. With the minimal debris production and constant filtration of the dielectric fluid, there is little risk of waste materials interfering with the manufacturing process. This combination of factors results in the high accuracy and intricate designs associated with Electrical Discharge Machining, making it an invaluable tool for machine shops.

What Are the Different Types of Electrical Discharge Machining?

There are several kinds of EDM, and choosing the correct one will depend on the material you are working with. Electrical conductivity and erosion resistance will affect the type of machining and electrode material required. The kinds of EDM are:

1. Wire Cutting EDM: This EDM uses a continuously fed wire as an electrode, and it is ideal for cutting through the entire thickness of a workpiece. It often uses brass or copper electrodes and ionized water as its dielectric fluid. Wire cutting EDM is limited in the range of complexity it can produce.
2. Sinker Discharge Machining: Known as Ram, die or traditional EDM, Sinker Discharge Machining uses a pre-shaped electrode to create complex geometries and partial cuts. This type of EDM typically uses graphite or copper electrodes that are the inverse shape of the piece it’s creating.
3. Hole Drilling EDM: This type of Electric Discharge Machining specializes in drilling small, deep holes, offering clean results without burrs. Its electrodes are tubular, and as dielectric fluid passes through the tubes, it minimizes deflection, resulting in highly accurate holes that conventional methods cannot produce.

What Are the Applications of EDM?

EDM shines in areas where traditional machining falls short, especially in machining electrically conductive materials, regardless of their hardness. Its applications span multiple industries, including automotive, aerospace, medical and even jewelry. 

Since Electric Discharge Machining can easily cut hardened steel, it excels at creating complex dies, molds and tools. EDM is also great for prototype creation because it allows for the exploration of different geometries without typical manufacturing limitations.

EDM’s drilling and burr-free capabilities are required for jet engines and turbines, as well as specialized lab equipment, surgical tools and implants. Not only does EDM work on tough materials, but it can also work on exotic materials, including those with high flash points, due to the use of dielectric fluid.

Should I Add EDM to My Machine Shop?

Electrical Discharge Machining offers a versatile and precise alternative to conventional manufacturing methods. Its ability to work with various conductive materials and create complex geometries makes it a valuable tool in modern manufacturing. To discuss how EDM can work in your manufacturing facility, contact Accurate Machine Tool Services today.