EDM is a process in which a conductive electrode is charged with electricity and brought into contact with a workpiece to thereby electrically erode away the unwanted portion thereof. Typically, a thin wire (from 0.002 inches to 0.014 inches diameter) is used as the electrode and is thus capable of precision machining. EDM is a very precise and complicated machining process that is typically controlled by an on-board computer.
All wire EDM machines come standard with a cartridge-type filter system for filtering the water used to flush the swarf or waste from the workpiece as it is burned away. Proper flushing of the workpiece is critical in attaining the high degree of accuracy and reliability required for most EDM operations. The standard cartridge filter on most wire EDM machines can be relatively expensive and, under heavy machining conditions, require replacement on a relatively frequent basis. This not only becomes expensive due to the cost for the replacement filter elements,the disclosures of which are incorporated herein by reference.
In order to minimize the expense and down time normally associated with the primary filter systems for EDM machines in the prior art, the inventors herein have succeeded in developing a prefilter which can be utilized as a kit to retrofit existing EDM machines and which can be incorporated into the design of new EDM machines. Essentially,sheet-type filter paper, a float switch in the tank for sensing the level of water in the tank and actuating a motor operatively coupled to the take-up roll for advancing the filter paper through the tank. The tank is designed to fit over the top of the water tank of an EDM machine and under the return water line such that the flush water which contains machine residue fills the prefilter tank and is processed therethrough prior to being filtered by the primary filter of the EDM machine. |
