Adding a Vacuum Chuck and Aspirator to Electric Discharge Machining Equipment.
Original Publication Date: 2001-Dec-13
Included in the Prior Art Database: 2005-Jun-09
National Institute of Standards and Technology
Paul C. Brand: INVENTOR [+3]
Today, Electric Discharge Machining (EDM) as a manufacturing process is well established. Several classes of parts that are machined with the aid of this process could benefit from the use of various vacuum-chucking techniques. These classes are: parts that are thin and/or difficult to hold using a vise or clamps; parts that would be distorted by traditional two-surface clamping methods, i.e. vises and clamps; parts requiring reference to a precision datum that cannot be supplied by standard tooling but could be by an EDM machined surface; and those circumstances, not yet envisioned, that would benefit from the single-surface clamping possible with a vacuum chuck but not practical or possible with a magnetic chuck. Vacuum chucks have the added advantage of not leaving tooling marks. Furthermore, in a production environment, vacuum chucks offer the possibility of fewer setups, faster cycle times, and higher yield. To the best knowledge of the inventers, vacuum chucks have not been used in EDM systems. Despite their versatility, they are only rarely used in machining practices. For general cutting processes, such as milling, vacuum chuck use is limited due to the high cutting forces typically present. In the case of EDM, tooling forces are minimal thus the vacuum chuck has far more versatility; however, the technology has not been utilized due, primarily, to difficulties resulting from the aspiration of water or oil, which are omnipresent in EDM systems. The subject invention addresses this concern by using a so-called aspirator as the source of vacuum (see Figure 1). An aspirator works by forcing a jet of liquid through a Venturi-tube and is normally used in chemical labs to provide the source of vacuum for various filtering techniques. In an operating EDM system there are several liquid pumps present that can be hard-plumbed into a commercially available aspirator pump. An aspirator is insensitive to the presence of even large quantities of liquid in the vacuum line. It therefore enables automatic continuous machining even while using a vacuum chucking system.