TL;DR
Contaminated dielectric fluid causes arcing instability, reduced cut speed, and surface quality degradation. Replace or treat the dielectric when conductivity and color fall outside the acceptable range.
What you might see
- dielectric fluid appears dark brown or black
- cut surface roughness increasing despite correct parameters
- EDM arcing unstable or irregular
- dielectric filter change interval shortening dramatically
Likely causes
Accumulated electrode erosion particles loading the dielectric beyond filter capacity
Cross-contamination from oil-based cutting fluids used on adjacent machines
Ion exchange resin exhausted allowing conductivity to drift high
Bacterial growth in stagnant dielectric fluid causing discoloration and odor
Required tools
- Replacement filter cartridges
- Replacement ion exchange resin cartridge
- Fresh deionized water or machine-specified dielectric
- Conductivity meter
- Protective gloves and goggles for fluid handling
Safety first
- Dielectric fluid disposal must follow local environmental regulations. Used dielectric containing electrode erosion byproducts may be a hazardous waste.
- Do not mix dielectric types or add oil-based fluids to the dielectric tank.
Procedure
- 1
Check the dielectric conductivity reading on the machine panel. Record the value and compare to the range in the Mitsubishi EDM specification.[1]
- 2
Inspect and replace the main filter cartridges if the pressure drop across the filters is above normal.[1]
- 3
Inspect the ion exchange resin cartridge for exhaustion. Exhausted resin appears dark brown. Replace to bring conductivity back into range.
- 4
If the fluid is heavily contaminated, drain the tank and dispose of the used dielectric per local environmental regulations. Clean the tank walls and filters before refilling.
- 5
Refill with fresh deionized water or the dielectric specified by Mitsubishi for the application. Do not use tap water.
- 6
After refill, check conductivity and allow the ion exchange system to stabilize before cutting.
Sources
Mitsubishi Mitsubishi MV2400R / MX600 EDM (Wire / Sinker) general technical documentation, Mitsubishi
Mitsubishi EDM operator and maintenance manual, dielectric system maintenance and fluid management (general)
More guides for Mitsubishi Mitsubishi MV2400R / MX600
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How to reduce wire break frequency on a Mitsubishi MV2400R / MX600 wire EDM
Frequent wire breaks are usually caused by incorrect feed rate for the material and thickness, degraded dielectric fluid, or contaminated wire guides. Check flushing pressure and dielectric conductivity first.
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