Electrochemical grinding, or ECG, is a variation of ECM and popular surface treatment that combines electrolytic activity with physical removal of material by means of charged grinding wheels. ECG can machine very smooth edges, without the burrs, caused by mechanical grinding tools, which require further machining. Like ECM, electrochemical grinding generates little or no heat that can distort delicate components.
The basic components of the process are a conductive grinding wheel, typically made of a matrix of copper, abrasive and resin, a tank that holds an electrolytic solution, and a direct current power source.
The wheel is mounted on an electrolytic spindle equipped with carbon brushes that serve as a commutator. The dc power supply charges the spindle negatively, and charges the workpiece positively.
When the workpiece contacts the wheel, a nozzle applies the electrolyte, typically sodium nitrate, much like coolant in conventional mechanical grinding. The coolant fills the tiny irregularities in the grinding wheel, creating an electrochemical cell that oxidizes the workpiece surface. The abrasive wheel carries away the oxide film, thereby exposing fresh metal to the process.
Unlike other surface treatment, because the oxidized material is fluid, it requires much less force to be removed. Pressures are frequently 20 psi or less, depending on the area of contact between the wheel and the workpiece. This virtually eliminates the distortion that purely mechanical grinding causes to metal surfaces.
The dissolved oxide surface puts very little wear on the grinding wheel. The wheel is essentially self-cleaning, which greatly reduces the dressing and truing required with abrasive stainless steel surface treatments.
"Like ECM, the hardness of the workpiece is not a factor affecting electrochemical reactivity, so we can machine the hardest alloys, including Hastalloy, Inconel, and Stellite"
Contact us for more information on this unique process.