A traditional machine shop has many different machines, some designed for a particular function, and others more adaptable. An electrical discharge machine, or EDM, might be the most important tool in a contemporary shop. Also known as a spark machining tool, an EDM machine cuts conductive materials using sparks or electricity. By eliminating material, it creates cuts using electrical energy.

EDMs present some comparatively innovative production technology, which is what makes them so unique. They utilize electricity to wear away at the metal, able to cut through any conductive material. There are several tasks in a machine shop where utilizing EDM is preferable to conventional machining techniques.

What is Electrical Discharge Machining?

In electrical discharge machining, material is eroded using electrical energy. That energy generates a series of high-frequency sparks between an electrode made of copper, brass, graphite, or tungsten and alloys from each of those metals and an electrically conductive workpiece.

When the spark jumps from the electrode to the workpiece, the erosion process removes excess material from the work piece, which is then flushed away by dielectric fluid. The fluid is typically a specific non-conductive oil or deionized water. Extremely fine finishes, and accuracy down to the micron, are both possible.

EDM comes in three primary types: conventional, also known as “sinker,” EDM hole drills, and wire EDM, also known as “WEDM.” 

What Is Wire EDM?

In Wire Electrical Discharge Machining, or Wire-Cut EDM, a thin single-strand metal wire is fed through the work piece, typically occurring in a submerged dielectric fluid tank of deionized water. This fluid helps to cool the process and flush away the cut material. The Wire EDM process uses electric current to cut conductive materials, leaving a smooth surface that requires no further finishing or polishing.

This process is used to cut plates and to make punches, tools, dies, molds, and parts from any conductive material, including hard metals that are too difficult to machine with traditional methods (such as metal alloys, graphite, carbide and diamond). 

All this means that a Wire-Cut EDM can be programmed to cut very intricate and delicate shapes. There is little change in the mechanical properties of a material in Wire EDMing due to its low residual stresses.

What Is EDM Hole Drilling?

There are several advantages and benefits to EDM small hole drilling.

  • The Capacity To Drill Through Curved And Inclined Surfaces. With small hole EDM, it is simpler to drill on curved or inclined surfaces since the electrode does not come into touch with the substance being cut.
  • Drilling Strong, Hard Alloys. Small hole EDM drilling is unaffected by hardness, making it the only drilling technique for some materials.
  • Gentler Metal Drilling. Aluminum and copper, two softer metals, frequently produce chips that stick to cutters. Drilling of such materials is accomplished using small hole EDM without chip production.
  • Digging A Deep Hole. Typically, small hole EDM drilling is the only practicable method for making small, deep holes. 
  • Straight And Clear Of Burrs. Straighter holes, which are difficult to create with standard drilling due to drifting, are produced by the no-contact procedure of small hole EDM drilling. Deburring, which is required with conventional drilling, can be avoided using small hole EDM drilling.

What Is Sinker EDM?

In sinker EDM, a custom tool-electrode (often referred to as just the electrode) approaches the workpiece-electrode (often referred to as just the workpiece), and a series of sparks—referred to as EDM pulses—between the electrode and the workpiece remove material from the workpiece while the electrode machines the workpiece into the desired shape. 

Molds, die sets, and other parts are made with sinker EDM in a variety of industries, such as the medical, aerospace, and power generation sectors. 

When EDM Machines Are Preferable To Conventional Machining Methods

1. They Can Complete Large Jobs

Generally speaking, traditional machines are made to operate primarily in automated situations, but they require upkeep. On the other hand, EDM machines are less prone to errors or interruptions and thus may be left to operate with little supervision.

2. They’re Amazingly Accurate

Some traditional machines can’t be used in specific situations, such as when cutting sharp internal corners. For EDM machines, especially wire-based models, this is not the case. With the right kind of wire, tension, and feeding, it’s possible to cut interior corners that are sharp and tightly packed and ultimately produce designs that would not be feasible using other techniques. 

3. They’re Capable of Deep Cuts

The materials frequently used in a machine shop are challenging to work with because they are so hard. This often meant developing designs that used shallow cuts to reduce the amount of effort required to make the cuts. EDM machines can make deeper cuts, even with very hard materials.

Additionally, such cuts won’t cause ineffective or problematic seams. In other words, regardless of how deep it must cut, the tool consistently produces a clean, dependable cut regardless of how strong the material. 

4. They Create Robust Molds

Due to the technology’s ability to cut through solid materials, operators frequently choose EDM machines over standard CNC machining when creating molds. 

Sometimes, to make a mold, two machining methods will be employed—first, a CNC mill will be used to make the negative shape, and then a wire EDM will be used to make the edges more precise. This is an excellent method for creating an injection mold. Furthermore, because the finished mold materials are so much stronger, costs are reduced because they need to be replaced less frequently. However, it also opens up a more comprehensive range of possibilities than would be conceivable with delicate or one-use molds.

It is possible to completely rethink machining and production when the molds made by EDM are combined with additive manufacturing techniques.

5. They Work Best with Hard Materials

Many materials, including some of the toughest in the field, may be bored through and cut with EDM devices. Even when meeting strict standards, the toughness has little impact on precision or maneuverability.

An EDM tool can effectively cut all conductive materials including tungsten carbide, hardened steel, titanium, Inconel alloys, and even materials like Hastelloy, composed of nickel and molybdenum. It is nearly impossible to cut these materials accurately using conventional cutting and machining techniques.

6. They Can Design A Distinctive Finish

EDM tools can indeed create surfaces like craters and pockmarks depending on the speed of the cut; this is typically the case when cutting swiftly. This can be a benefit when altering different parameters. For instance, cutting at lower power minimizes flaws and yields a smoother surface with a mirror-like gloss.

Operators can make adjustments to enhance the completed product and cut down on extra stages. Other tools are not required to obtain the same result because you can attain that mirror-like finish. This helps provide excellent work while also accelerating overall output.

Better Results Are Available With Electrical Discharge Machining

EDM technology isn’t perfect for every case or application because it can’t be utilized to cut materials like plastic or plaster. But electrical discharge machining offers many advantages when it comes to hard conductive materials or metals.

Your company will gain from unmatched precision and the ability to make deeper cuts and produce more refined edges while encountering less resistance. EDM tools can operate as much as required, with no interaction, even in an automated “lights out” facility, because they are very reliable.

At the very least, there is no excuse for your machine shop not to have an electrical discharge machining tool (or a few) on your shop floor. Sodick is ready to help you assess your requirements