Another component of preventative maintenance is checking all machine components to make sure they’re in proper working order. These include cables, the wire transport system, rollers, bearings and flush cups.

Wire EDM operates with high frequency current that uses the outer surface of the cables. Cables are the number one cause of speed loss in an otherwise normal machine. There are three types of cables on most wire EDM machines: ground cables, auxiliary cables and power feed cables. Auxiliary cables are used on larger machines to shorten the distance the current has to flow, improving cutting speed. These cables can improve cutting speeds .005~.015”/min. depending on material thickness.

They should be replaced at the first signs of wear—including a broken attachment clip, ripped cover or residue build-up caused by improper cleaning. Power feed cables bring the cutting current to the machine heads from the power supply. They’re normally a coaxial type cable with the outer shielding used as the return ground. Broken power feed cables can result in up to a 40 percent loss in cutting speed. It’s recommended that these be replaced every three years. Do not try replacing your ground cables with automotive type jumper cable; it is not the same thing!

The wire transport system includes everything from the wire spool to the waste basket. Wire pretension motor, main tension brake, limit switches, wiper pads and rollers all have to be checked regularly. Wire guides, set screws and contacts all play a part in wire stability. Keeping them clean will prevent clogging and inaccuracies in part quality.

Inspect all rollers and bearings for smooth operation and wear. Bad bearings create vibration and can cause lines in the workpiece surface. Worn grooves can cause wire curl that can hinder machine operation.

Flush cups direct the high pressure flush into the gap to remove sludge quickly. Chipped, cracked or broken cups allow that water pressure to escape to the sides, resulting in reduced cutting speed.