Why does surface rust appear on stainless steel rulers used in Wire EDM WEDM?

Rust on an MXRuler is usually external contamination from a rusted workpiece, contaminated coolant, or poor water quality. The rulers are made from corrosion-resistant 440C stainless steel. These deposits come from contamination sticking to the ruler, rather than rust originating in the ruler itself.

Surface deposits on ground areas usually wipe off easily.

Common causes include:

• High pH levels in the water. Test with a suitable water test kit and change the water if needed.
• Tap water containing minerals or metals. Use softened or deionized water as appropriate for the machine.
• A water-quality meter reading below the original recommendation of 50 kΩ. Check the deionizing bottle and confirm the meter units and operating range in the machine instructions.
• Contaminated or rusted workpieces depositing particles in the system.

Counterbores, screw holes, unground surfaces, and other areas with low water flow can collect deposits. Scrub these areas at the end of each day and dry the fixturing. Monitor water quality and keep rusted components out of the system.