– By Industrial India Content Team
Electric Discharge Machining or EDM is a popular method of metalworking adopted by manufacturers. It gives them the ability to work-hardened metals and on ceramics to make complex components in an accurate manner and it has a diverse application across industries.
In this process, metal is worked by applying heat to it via an electric spark without the tool and the work material actually touching. Also known as spark erosion, the principle behind it is simple. The tool and material are connected to a D.C. source via a cable. Electric current is then fed and the tool and material are slowly brought closer together. When the gap is close enough, it ignites a spark that then erodes the metal. Also, known as Spark Erosion Oil or the dielectric, this fluid acts as an insulator, conductor, coolant and cleaner all in one. When the ‘spark-gap’, as the distance between the tool and material is called, is narrow enough the fluid ionizes, opening up a conductive corridor that allows the spark to ignite and erosion to take place. When the spark stops, it cools the material which can reach as high as 8,000 to 12,000 °C. Even more crucially, it plays a vital role in flushing away the eroded material which can otherwise render the process inefficient, damage the tool, resulting in a higher wear rate of the electrode but not erode the metal fast enough.
Electro Discharge Machining can trace its roots back to 1953 when two Russian scientists realized the erosive effect of capacitor discharges could be applied to the processing of metals. The scientists, B.R. and N.J. Lazarenko first used air as a dielectric. But they quickly came to realise that mineral oil-based fluids were far more suited to the process.
Today, there are a multitude of EDM oils available in the market place, each with its own insulating, conductive, flushing, ionizing, viscosity and cooling properties. Regardless of their composition, they all need to have stable dielectric strength to provide adequate insulation until the breakdown voltage is reached, low viscosity and effective cooling properties; it should be able to flush out the particles produced during the erosion process, be chemically neutral and have a high flash point so as not to be a fire hazard. It should neither emit toxic vapours nor unpleasant odours. Above all, it should retain all these properties despite temperature variations, contamination of eroded particles and those that result from decomposition.
Some manufacturers use kerosene-based SEOs. There’s a downside to this. Kerosene use leads to lots of problems while machining: its properties as a dielectric degrade fast, air pollution and carbon particles can easily get deposited on the workpiece when using kerosene. Overall, it lowers machining efficiency. The most effective SEOs tend to be mineral-based, like IPOL SEO 450. They are versatile, easy to use and have great efficiency. IPOL 450, for instance, is a low viscosity product which minimizes electrode wear and has excellent flushing properties. It also has high dielectric strength, which improves precision and control sparking. At the same time, it has a high flash point (110°C compare to Kerosene i.e. 40°C), making it less hazardous to work with. It has a uniquely selected hydrocarbon base. It’s virtually colourless, making it easier to machine parts, and doesn’t have a strong odour or fumes. Because of these properties, GP Global’s IPOL SEO 450 is one of the most popular with manufacturers and has been used in different industries for more than 25 years now. Ultimately, with spark erosion gaining acceptance, it is more important than ever that manufacturer’s select the right spark erosion oil.
