Everything about Electrical Discharge Machining (EDM) Explained

Your decision to use an electrical discharge machine for prototyping and other jobs can only be settled when you are certain what this machining process is.

Today, we will explore everything about EDM machining process – from basic to advanced concepts.

What is Electrical Discharge Machining?

Electrical discharge machining, or EDM, is a unique non-traditional cutting or machining method that uses managed electrical sparks to cut and shape workpiece. This method uses thermal energy in its operations. This energy is produced when electrical discharge is converted.

Advantages of EDM

  • More liberty with your designs

With this method of machining, you have the liberty with designs. Although the normal machining methods come with restrictions, EDM will provide you with total liberty where complicated depths and design cuts are concerned.

  • No issues with the process getting distorted

With EDM, there is no direct meeting between the tool and the workpiece being worked on. Due to this, distortion doesn’t happen, and this makes it possible to use the perfect method for machining thin workpieces.

  • Precise surface finishing

With EDM, you will never have to worry about machining marks being left on the surface of the workpiece. This makes the work perfect and precise without requiring more treatments.

  • Precise cuts

EDM is perfect if you want to have workpieces cut to perfection. They are designed to ensure each part or prototype you work on is perfect.

  • Works with various materials

Although some machining processes cannot work with materials that are hard, that is never the case with Electrical discharge machining. No matter how hard the material you need machined is, this method will meet your needs.

Limitations of EDM

  • Isn’t ideal for you if you need them for projects that are large-scale. This is because material removal rates are quite low.
  • You will experience some restrictions when machining some materials with EDM, especially materials that aren’t electrically conductive.
  • You need electrodes for die-sinking with Electrical discharge machining. This means that when you are not manufacturing in large quantities, electrode machining is mostly costly.
  • This method isn’t environmentally friendly. You need to know that electrical discharge machining needs a lot of electricity to work, which makes it quite unfriendly to the environment.
  • You might find it hard to get experts with experience in EDM.
  • Since high heat can be developed when this machining process is undergone, metallurgical features in materials get altered.
  • This machining tool wears out with ease.
  • It isn’t possible to have sharp corners reproduced.

When to use Electrical Discharge Machining

Below are some places where you can introduce electrical discharge machining:

  • Used when extrusions need to be cut
  • Is needed for micro-hole drilling
  • Helps when sharp internal corners need to be cut
  • Helps to drill holes that are curved
  • Is needed for rotary form cutting
  • To create tools for injection molding
  • Hard material for engraving purposes
  • To ensure workpieces have no broken tools

Electrical Discharge Machining History

This whole process started in the 1940s, when Soviet scientists N.I. and B.R. Lazarenko wanted to make use of the power electrical sparks brought.

These scientists started this whole procedure, which was put in place in the beginning to ensure the eroding of tungsten electric contacts wasn’t welcomed. It was the discovery these two initiated that brought this machining to life. Over time, this method has become exceptional, with unique advancements taking over.

Although wire electrical discharge machining is how it all started, there have been unique changes and transformations. Today, this process shows how much the human mind has evolved.

Integrating EDM and CNC

Below are details where EDM and CNC integration are concerned:

  • As far as these machining systems are concerned, you should know that CNC stands as the connecting interface between design and implementation.
  • CNC ensures that the machine is well programmed and that electrode movements are accurately controlled.
  • CNC, being attached mostly to CAM or CAD devices, makes it possible for design specifications to be directly moved into the process of machining. This makes it possible for you to get the ideal end result you have always longed for.

Types of Electrical Discharge Machining

Sinker EDM

This type is also called the die-sinking or the ram electrical discharge machining type.

  1. Under this method, you will need to have the workpiece and electrode brought together and immersed in the dielectric fluid. This leads to some discharges or releases electrically, which erode workpieces to achieve ideal machining outcomes through mirroring.
  2. Where shapes that are specific and precise are needed, you can consider this type to work perfectly.
  3. Since you have much more control over the movement of electrodes with this type, it is easier for you to achieve accuracy and personalization.
Sinker EDM

Sinker EDM

This type of EDM has proven to be a major problem solver for most manufacturers in the machining industry.

Wire EDM

Wire electrical discharge machining is famous for being very accurate. Also, it is known for other things:

  1. With the wire EDM process, a wire made out of coated copper or brass is used as the tool for cutting. Mostly, the wire is thin and has electrical power.
  2. It is the wire that slices through materials as feeding is done step by step.
  3. You can easily create full, thorough, and complex cuts with this EDM type.
Wire EDM

Wire EDM

Hole Drilling EDM

Also referred to as the fast hole drilling method, it is a unique procedure set up to quickly create holes that are deep and precise. Some more details include:

  1. You will need to use tubular electrodes under this EDM method to have holes blasted perfectly.
  2. If you need quick turnaround times achieved with your cuts, this method is best.
Hole Drilling EDM

Hole Drilling EDM

Multi Axis EDM

As the normal EDM methods keep evolving, the multi-axis method seems to be leading the way. Know the following:

  1. This method stands out as the only one that includes more movement axes. Due to this, it is able to machine shapes that are complex.
  2. You can be assured of complete flexibility with this method.
Multi Axis EDM

Multi Axis EDM

Micro EDM

This method represents an infusion of the normal electrical discharge machining method with very minute procedures that are detailed or fine-tuned. If you are in an industry that requires making a lot of miniature products, this type is ideal for you. This type will come with the highest level of accuracy and detail you need with materials machined.

Micro EDM

Micro EDM

EDM Milling

Under this type of electrical discharge machining, there is the use of an EDM head. The movement of this head in the pattern of milling leads to all machining work being perfectly achieved in detail.

If you wish to machine components that will need complicated geometry that the normal milling methods cannot help bring to life, this type of EDM will make it happen.

EDM Milling Machine

EDM Milling Machine

Wire Thread EDM

This type of EDM is a unique method where wire EDM’s are classified. Under this method, you will need to ensure the start hole is well threaded. This threading, when done well, is what makes the whole machining process very smooth.

If you need wire to go through or pass through geometries that are complicated, this type of EDM is ideal.

Components of EDM

· Guides

Also known as ferrules. This component is made of ceramic. It does its work by guiding electrodes to the specific workpiece that requires shaping.

· Electrode

An electrode will ideally come in the form of tubes, wires, or even dies.

· Dielectric Fluid

This component is responsible for cooling workpieces and electrodes. Also, they go further to ensure eroded materials are moved away from workpiece areas that have been machined.

· Supply of Current

It is the energy that sparks electrodes. This ensures that the right power required for precision is achieved.

· Control Unit

You will find this component laying at the center of the electrical discharge machining device. This is where everything with regards to the machine is controlled.

· Dielectric Systems

This system for electrical discharge machining meets different needs. It stands between workpieces and electrodes. Also, it has a reservoir or container that has dielectric fluid in it. This fluid is mostly deionized water or oil.

· Pump

This component makes the movement of dielectric fluid from the bottom of the container to the tool very easy.

· Working Tank

This component is the place where all machining processes with this method happen. It is a container that has both the fluid and workpiece brought together to be machined.

· Workpiece Fixtures and Holders

This component ensures workpieces are held in their right places. This ensures that even when machining is taking place, the workpiece doesn’t move to ensure there are no mistakes.

· Servo Control

This component works to ensure the gap between electrodes and materials is fixed or adjusted. It also works to ensure spark generation is well controlled to achieve precision all around.

· Flush System

This component acts as a support, and it also plays a very important role in the whole EDM process. This part makes sure there is a flow of dielectric fluid that is progressive to improve the removal process.

· Voltmeter

This component in the EDM machine is used to measure voltage.

· Ammeter

This device works by checking if current flows or not. However, it needs to be linked before you can use it for these checks.

EDM Components

EDM Components

How Electrodes Affect Electrical Discharge Machining Process

Different electrodes come with different properties. These differences are what will affect your EDM process, either negatively or positively. Below are some ways these play out:

  • A brass electrode, for instance, will lead to materials eroding quickly compared to tungsten and other materials.
  • Brass electrodes are easy to extrude or machine. So, they are used more in wire electrical discharge machining processes.
  • Copper is able to resist wear better than brass does. Also, it is very hard to machine compared to brass. However, with copper being a great conductor, it works perfectly if you need workpieces to have a fine finish.
  • Copper can also be added with tungsten to achieve the finest copper tungsten electrode machining processes.
  • Dielectric fluid filtration system. This system makes sure dielectric fluid is free from all unsave particles and is clean to perfect the machining process.
  • System for cooling. This system helps to keep the machine from overheating and to ensure its operation safety.

Step-by-step Electrical Discharge Machining Process

EDM Working Principle

EDM Working Principle

Step 1 – Prepare the items needed.

You need to prepare the following:

  • The electrode.
  • The material or workpiece.
  • EDM machine.
  • Safety wear (gloves, eyewear)
  • Dielectric fluid.

Step 2: Mounting the workpiece and electrode

Begin by mounting your workpiece and electrode. When mounting these, make sure a small distance is left. So, the tip of the electrode shouldn’t touch the workpiece.

Step 3: Turn on and off the dielectric supply

You will need to turn the dielectric supply on, to have the workpiece and electrode immersed in dielectric fluids. After that, turn it off.

Step 4: Setup Command via Control Unit

Initiate the command for machining to begin via the control unit. This ensures the right amount of power is created to have the right sparks take over.

Step 5: Melting and Vaporizing stage

Electric sparks, when generated, result in thermal energy, which is high. This causes metal to melt and vaporize; thus, machining is achieved.

Difference between CNC and EDM

  • CNC requires physical contact with workpieces, and EDM doesn’t require that.
  • CNC cuts with a cutting tool that is sharp, while EDM uses electrical discharges or sparks for workpiece shaping or cutting.
  • Cutting complex designs is easier with EDM, while it is very difficult with CNC.
  • EDM costs more to machine workpieces, while CNC doesn’t cost so much.

How to Choose Right Electrical Discharge Machine

Here are some tips to decide on the right EDM:

  • You need to check the abilities of the machine where hole tapering is concerned.
  • Check the size of the machine and your space.
  • The dielectric fluid it uses. It is important that you use the right fluid.
  • Be sure it has a smooth maintenance structure.
  • Compare prices to be sure you invest in what meets your budget.
  • Is it easy to use? You must consider this greatly.

Material you can Machine with EDM

Although versatile, EDM is able to work with some materials more. Below are those:

  • Steel- This includes stainless and hardened steel types that are very tough
  • Copper- Has great electrical conductivity
  • Aluminum- It is not heavy, but very strong
  • Inconel- Is able to stand against temperatures that are extreme. Also, it is a nickel alloy
  • Brass- Machining is very easy with brass.
  • Graphite- Works perfectly for the EDM process
  • Titanium- Resists corrosion and is very strong
  • Hastelloy- Highly resistant to corrosion
  • Tungsten carbide- Resists wear and is very hard
  • Kovar- This alloy is able to stand against different thermal expansion levels
  • Gold
  • Silver- Has great electrical and thermal conductivity.

Best Software to use in EDM

Listed here are the best apps you can use for EDM:

  • CAM and CAD integration. This app, brought together, is able to transform intricate and complicated designs into reality. It does this through the guidance of the machine.
  • Simulation app. This app is used for visualizing and optimizing the whole procedure before it begins. When this is done, you get to know all the probable inefficiencies or errors. So, time is saved and material waste is prevented.
  • CNC software. This interface is what offers the machine with its programming operations. This ensures the right amount of electrode movement control.
  • Process Monitoring and control software. This software help to adjust current, voltage, and more to ensure work output is perfect.
  • Toolpath Generation Software. It is used to have specific paths generated for the tool to follow. This leads to high accuracy levels.

How EDM Compare to Other Machining Processes

Here are some things that makes EDM different from other machining methods:

  • Contactless process. EDM is contactless in the sense that, you do not have physical contact with the material. Electrical sparks or discharges do the work here. This cannot be said for traditional or other machining methods.
  • Hardness of the material. It is easy for you to machine materials that are very hard using the EDM method. Sadly, traditional methods of machining find it hard to achieve this.
  • Accuracy and intricacy. If you want to have complex shapes and accurate details that are perfect, EDM is the go to method. However, you cannot count on traditional methods of machining for the same outcomes.
  • Surface finishing. The level of surface finishing that you get with EDM will always be higher. So, you will not need a process for post machining. This, however, cannot be said where other machine methods are concerned.
  • Wear of the tool. It is not frequent to experience tool wear where EDM is concerned as compared to other processes. Also, maintenance is not complicated with EDM.
  • Setting up the process. EDM setup is mostly complicated and consumes a lot of time. This is even worse when you have intricate designs done. However, other machining methods are not.
  • Restrictions on workpiece materials. EDM is able to work perfectly only with materials that are electrically conductive, but traditional machining is able to handle different types of materials.
  • Cost of operation. You will spend much more on operating EDM as compared to other machining methods. This is because of the specialized machines needed, the use of electricity, and maintenance.

Electrical Discharge Machining Applications

Below are some industries you will find electrical discharge machining being used primarily:

  • They are used here to create dies for the parts of cars and also molds for car parts.
  • Used to machine engine parts and turbine blades.
  • Tool and die production. Used to create stamps, dies, and molds.
  • Medical devices. Ideal for producing complex surgical devices and implants.
  • Is beneficial in creating parts for wind, nuclear, etc.
  • Used to make connectors and semiconductor parts.
  • Machinery for manufacturing. To machine threads, gears, and other unique machinery components.
  • Research and Development. Ideal for experimental part prototypes and creation.
  • To create components used in military vehicles as well as equipment.
  • Ideal for creating infrastructure parts and connectors.

FAQs

How Accurate it EDM?

Electrical discharge machining is able to attain a tolerance of +/- 0.0002. This makes it very precise and accurate.

Which Finishes can ELECTRICAL Discharge Machining Achieve?

Electrical discharge machining doesn’t end up leaving marks on workpieces. So, you can expect superior surface finishes with this machining method. Note that, the level of cutting speed also determines the perfection of the finish.

Conclusion

Understanding the uniqueness of the electrical discharge machining process is definitely something that will help you. In all these details provided, you need to ensure the right machine is used to make the process super easy.

More resources:

Sinker EDM vs. Wire EDM – Source: TSINFA

Sinker EDM – Source: TSINFA

EDM Machining – Source: IQS DIRECTORY

EDM – Source: XOMETRY