Wireless Monitoring of Workpiece Material Transitions and Debris Accumulation in Micro-Electro-Discharge Machining

Wireless signals are inherently generated with each discharge in micro-electro-discharge machining (¿EDM), allowing direct observation of discharge quality. While traditional methods of monitoring machining quality rely on electrical characteristics at the discharge supply terminals, the wireless me...

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Bibliographic Details
Published in:Journal of microelectromechanical systems 2010-02, Vol.19 (1), p.48-54
Main Authors: Richardson, M.T., Gianchandani, Y.B.
Format: Article
Language:English
Subjects:
Applied sciences
Bandwidth
Batch-mode micromachining
Biological materials
Biomedical materials
Condition monitoring
Copper
Debris
Exact sciences and technology
Fault location
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Machining
Mechanical engineering. Machine design
Mechanical instruments, equipment and techniques
Micromachining
Micromechanical devices and systems
Monitoring
Physics
Position (location)
Precision engineering, watch making
process monitoring
Signal generators
spurious discharges
stainless-steel machining
Steel
wireless feedback control
Workpieces
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Description
Summary:Wireless signals are inherently generated with each discharge in micro-electro-discharge machining (¿EDM), allowing direct observation of discharge quality. While traditional methods of monitoring machining quality rely on electrical characteristics at the discharge supply terminals, the wireless method provides more accurate information because it is less affected by electrical parasitics in the supply loop and by spatial averaging. The depth location of a metal-metal interface can be distinguished in the wireless signal. This is useful for determining the stop depth in certain processes. For example, in machining through samples of stainless steel into an electroplated copper backing layer, the metal transition is identified by a 10-dBm change in wireless-signal strength for the 300-350-MHz band and a 5-dBm average change across the full 1-GHz bandwidth. As debris accumulate in the discharge gaps, shifts in the wireless spectra can also indicate spurious discharges that could damage the workpiece and tool. For example, when copper micromachining becomes debris dominated, the 800-850-MHz band drops 4 dBm in signal strength, with a 2.2-dBm average drop across the full 1-GHz bandwidth.
ISSN:1057-7157
1941-0158
DOI:10.1109/JMEMS.2009.2035642