Wire EDM machining is an unconventional subtractive manufacturing process that excels in cutting hard metal materials.
When choosing a machining technology, most people think of machining, and the first thing that comes to mind is CNC Milling and CNC Turning. There are many other machining technologies on the market, and there may be one that is better suited for your application. Although wire-cutting machining technology is unsuitable for all applications, it is an essential machining process for many CNC machining shops, and even many companies would highly recommend this machining technology. The reason for this may be because of its accuracy, with wire EDM being able to achieve accuracies of up to +/- 0.00004″ (0.001mm), with the overall market accuracy being +/- 0.0002″ (0.005mm). While this accuracy is not achieved in all applications, it is a testament to the excellence of the process.
In this article, we will look more in-depth at wire EDM, its principles, advantages, why it is so accurate and where it can be used, and how Elimold believes that only a thorough understanding of technology can lead to selecting the correct method.
What is wire EDM?
Wire EDM is one of the many metal fabrication processes; it is a non-contact subtractive manufacturing process. It is similar to traditional machining, but the processing principle is entirely different from traditional machining, and in some ways, it is unique.
If you feel strange seeing “wire cutting,” it has many other aliases: EDM wire cutting, EDN cutting, EDM wire cutting, wire burning, wire etching, wire erosion, wire EDM and “cheese cutting machine” EDM.
Wire EDM uses metal wire to cut a workpiece, usually a thin, electrically charged wire and a dielectric fluid, following a precisely written path to cut the metal part into a set shape. It does this by melting or evaporating and separating tiny pieces of the electrode from the workpiece, which is washed away and filtered out in a cycle of dielectric flow. The principle differs from conventional machining, where a tool cuts the material.
In the wire-cutting process, there is no direct contact between the wire and the workpiece, which does not distort the wire’s path or the material’s shape due to machines or tools, etc. Also, due to the nature of this process, wire EDM is used for conductive metals and can cut through tough metals, including hardened steel, tungsten, titanium alloys, etc.
The working principle of wire-cutting machine processing
Wire EDM requires wire cutters, cutting wire, dielectric fluid, tools, and workpieces, and this process has a simple mechanism. The wire is usually supported by brass or layered copper and has a diameter between 0.1 and 0.3 mm.
The primary process starts with drilling a hole in the workpiece or starting from the edge, immersing the workpiece in the dielectric fluid and fixing it with a mechanical clamp, then passing the wire through the pre-machined hole or edge of the workpiece, where each discharge creates a crater in the workpiece in the machining area. The cutting line moves along the x and y axes as directed, and the cutting line can be tilted so that this process can make parts with taper or different contours. In principle, as with other EDM processes, the wire and the conductive workpiece carry an electrical charge, and the current discharge generates sparks between the wire and the workpiece, which erode the workpiece. Finally, the tiny particles are flushed away by a dielectric fluid.
Depending on the required accuracy and surface finish, the part may be rough machined once first to provide sufficient accuracy for specific jobs.
How accurate is wire cutting
Wire cutting is used to cut the desired part shape out of conductive materials. It can be cut in all directions.
Wire diameters for EDM range from 0.004″ (0.100mm) to 0.013″ (0.33mm), most commonly 0.010″ (0.254mm). It sparks when it cuts 180 degrees forward. The kerf width becomes wider. The actual width depends on the power supplied. It is usually about 1/3 larger than the wire diameter. A 0.10″ wire cut will produce a path approximately 0.13″ wide.
The speed and accuracy of wire cutting are controlled primarily by managing the cutting parameters and controlling the fluid flush rate. Using lower power and speed can improve accuracy. Because flushing moves the wire, flushing pressure increases significantly at high feed rates. Also, the wire will bend slightly due to the barrel phenomenon, which is more noticeable at higher speeds.
Tolerances of +/- 0.001″ can be achieved in relatively fast roughing processes. A flushing pressure of about +/- 0.0005″ can be achieved by cutting off the power and reducing the skim. A second skim is then performed to increase the accuracy of the EDM to about +/- 0.0002.
Advantages of wire cutting
EDM has unique advantages not found in traditional machining, making it the preferred process for machining complex parts in all production industries. First, it can machine very complex part shapes with high precision as well as have the ability to handle rigid materials. Also, due to the principle of the EDM process, there is no direct contact between the tool and the actual part being machined, making it easy to obtain an accurate and burr-free smooth surface finish. The advantages of EDM can be summarized as follows.
It allows for precise and accurate cutting without further machining and finishing the part.
The process is suitable for creating complex designs and shapes that would otherwise be difficult to produce using conventional CNC machining.
It is suitable for machining small parts and cutting highly detailed items that would otherwise be too delicate for other machining options.
EDM wire-cutting is ideal for fragile materials that cannot withstand machining stresses.
The machine cuts the material with only one processing stage without leaving burrs or distortion.
The machining process cuts continuously without interruption. Even if the wire is broken while cutting, the process continues immediately.
Applications of wire cutting
Wire cutting is commonly used in conventional machining processes to cut thick, rigid metal sheets. It is a popular process for producing punches, tools, and dies. Wire cutting does not cause part distortion and produces a good surface finish. Wire cutting is used in a wide range of applications, and the process is commonly applied to parts related to the aerospace, automotive, and medical industries, with more applications.
Manufacturing jewelry
Thick plate
Extrusion dies
Punching punches
Automotive and aerospace parts
Tight tolerance parts
Medical and dental equipment
Parts where burrs are unacceptable
Thin parts that may break during conventional machining
Graphite electrodes for EDM
Summary
Wire EDM is a versatile and precise machining process that can be used for hard materials and complex shaped parts. It is often used in industries requiring very high precision in parts, such as aerospace and medical. In this article, we hope you now have a clear understanding of the WEDM process. This includes the principles, benefits, capabilities, etc.
Are you seeking a professional manufacturer to help with your wire EDM project? Elimold is a manufacturing services company with pervasive experience in all CNC machining technologies, including the wire EDM process. Our team of experienced engineers can help you create any part and application you require. All you need is to send us the part drawing now. We will be happy to work with you to find the right solution.