EDM (or electrical discharge) machines are one of the most popular CNC machine tools around. They belong to the class of machines capable of starting with raw material, like a block of steel, and making very complex parts with precise tolerances and amazing repeatability.

EDM machines are used for many different types of metal fabrication and for cutting various materials from soft iron alloys to steels. The EDM process itself is relatively straightforward, but there are things to consider before deciding if an EDM machine is suitable for your shop or business.

EDM Machines Work By Using Electricity To Cut Metal

EDM is a common machining method often reserved for difficult-to-machine materials such as hardened steels and superalloys. It’s used to produce parts from these materials when conventional methods are too costly or impractical.

EDM machines use electricity to cut metal by plasma cutting, which involves a thin wire being charged with electricity and placed into a spool called an electrode. The wire is then fed through the spool to discharge into whatever material needs cutting—plastic or steel.

The EDM process relies on an electrical charge to create a spark that cuts metal. To do this, the machine uses electrodes or metal parts with wires coming out of them.

The electrodes are placed in a cutting fluid and connected to an electrical power source, usually a standard outlet. EDM works by placing the workpiece into an electrically conductive bath (called an electrolyte) which contains metal ions. When a small electrical current is passed through the electrolyte, it creates an electric field that attracts the negative ions in your material (i.e., iron). 

A high-voltage electrode will then create an arc between itself and your workpiece, removing those positive charges to make room for more negative ones on your part while simultaneously melting its surface layer. The result is a clean circular groove around its circumference where only solid material once existed.

Turning on the machine creates a circuit between the electrodes and the ground (called a “return”). To make sparks, electricity must flow from one electrode through the cutting fluid and back through another electrode so there’s a complete electrical circuit between them. This happens when you turn on your EDM machine: Electricity flows from one electrode through your workpiece (your metal piece) and back into another electrode so there’s now current going around two circular paths within the metal at once.

How Fast Do EDM Machines Operate?

EDM machines are some of the fastest machine tools in the world, capable of cutting up to 250 inches per minute. Many factors determine the speed at which an EDM machine operates:

  • Material type
  • Cutting length and thickness
  • Tooling and setup

The Roles Of The Electrodes In The EDM Process Are Reversed

In the EDM process, a positive electrode is replaced with a negative one and vice versa. This switches the roles of the electrodes in the EDM process. When an electric current passes through your motor, it generates heat. The heat causes carbon to melt, forming an arc between the wire and electrode. The melted carbon then floats away from its original location, where it creates your groove or whatever shape you’re trying to create in metal.

EDM cutting fluid, or dielectric fluid, serves several purposes during the process. It cools the workpiece to prevent thermal shock as it passes through the cutting zone. The dielectric fluid also cleans the surface of your workpiece, removing any dirt or debris on it.

If you were to look closely at a spark discharge between two wires, it would appear like they were burning off excess material from one wire onto another. If no dielectric fluid were present, this would happen immediately and cause damage to both wires (and possibly even damage to your machine). The dielectric fluid prevents this from creating an insulating barrier between the two wires until enough buildup has occurred for current flow through them to happen again.

Because the cutting wire never makes contact with the workpiece throughout the EDM process, no stresses are added to the component. As a result, less stress may be used for creating slots, grooves, and eyelets in machined items using EDM.

The coolant also lubricates both wires to move smoothly past each other without getting stuck together or overheating due to friction caused by poor lubrication. 

EDM’s superior finish is one of its additional advantages. With tight tolerances, the wire cutting process produces surfaces that are burr-free and smooth. In fact, wire EDM can be used to create through-slots and very thin eyelets for medical devices—features that are inaccessible to traditional centers.

How Noisy Are EDM Machines When Operated?

When comparing the noise level of an EDM machine to other machining methods, it’s essential to remember there are many different types of EDM machines on the market. Some are pretty loud, while others are much quieter. For example, you might think a plasma cutter would make a lot of noise because of all its sparks, but it’s significantly quieter than an electric motor running at full speed.

Similarly, although an EDM machine may use electricity for power instead of air pressure like with a milling machine or router bit (and therefore produce less heat), this doesn’t necessarily mean it’ll be quieter than these other options. It depends on how well built your particular unit is and what kind of material you’re working with; certain materials are naturally noisier than others when being cut into or drilled through (for example, metal tends to be louder than wood). In general, most EDMs tend not only to produce less heat but also require less airflow around them during operation, resulting in lower overall noise levels due to reduced air turbulence generated by their cutting action.

What Are The Maintenance Requirements On An EDM Machine?

EDM machines are more complicated than other machining methods, requiring more maintenance. There is a weekly, monthly and yearly maintenance recommendation. These recommendations are located in the machine tool’s manual which is supplied with the machine.

As part of operating an EDM machine, you’ll need to clean and lubricate it regularly. You may also have to inspect and maintain it regularly, as well as calibrate it from time to time. Sodick offers service and maintenance for the machines it sells

How (Or When) Is An EDM Machine Better Than The Alternatives?

Regarding precision, speed, and ease of use, EDM machines have few rivals. The machines allow you to create complex shapes—even ones that would be impossible by any other means.

As for what an EDM machine can’t do: They’re not good at cutting soft metals like aluminum or copper. However, they aren’t really meant for those materials anyway (in fact, most EDMs won’t even work on them).

It is best to consult a professional when deciding which machine is suitable for you. The variables involved in choosing an EDM machine include the material being cut, its hardness, and how much material to remove. Sodick is here to answer all of your questions.

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