| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 104 === The integrated apparatus for detecting ferrous debris concentration and viscosity in
EDM fluid has been developed successfully. This apparatus contains a sampling unit,
and measurement units of the ferrous debris concentration and viscosity with a displayer
unit. Measurement unit of the ferrous debris concentration adopts Ferrography
technology, where ferrous debris are captured at the gap between the poles of magnet to
change the magnetic flux, and its concentration is measured by using the output signal
of Hall effect sensor. Measurement unit of the viscosity uses a piston to squeeze the
EDM fluid in a hydraulic cylinder, and a load cell is used to measure the squeeze load.
The output signal of load cell is transformed into the viscosity of EDM fluid.
The ferrous debris concentration is calibrated using the given concentrations, and
the maximum error is less than 2.3 ppm under numerous tests. The viscosity is
calibrated using the general purpose viscosity fluids, and the maximum error is less than
5% under numerous tests. The ferrous debris concentration and viscosity in EDM fluid
are detected using this integrated apparatus, and the effect of ferrous debris
concentration on material removal rate and surface roughness of the machined
workpieces is investigated. Experimental results show that this apparatus is capable of
detecting ferrous debris concentration in EDM fluid. On the other hands, ferrous debris
concentration in EDM fluid has an appreciable impact on the material removal rate and
surface roughness of the machined workpieces. To maintain the performance of EDM
machine, it is necessary to change the EDM fluid when the ferrous debris concentration
is larger than 270 ppm. This indicates that the general EDM machine equips with a
detecting apparatus for ferrous debris concentration in EDM fluid is important.
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