Buying guide
Buying a used EDM machine: wire or sinker
Published on October 13, 2026
Wire EDM, sinker EDM or EDM hole drilling: the generator, the dielectric and the accuracy of the axes determine the machine's value. The points to check and the costs to plan for.
An EDM machine works without contact and without cutting forces: well maintained, it keeps its accuracy for a long time. But it relies on a sophisticated electronic generator and a demanding dielectric circuit. A careful visit avoids unpleasant surprises.
The right process and the right capacities
- Wire EDM: X, Y, Z travels, U/V taper angle, maximum workpiece weight and dimensions, usable wire diameters.
- Sinker EDM: travels, tank size, maximum electrode weight, electrode changer and C axis where applicable.
- EDM hole drilling (EDM drill): diameter range and depth, useful for wire start holes.
- CNC control: version, ability to read your files and compatibility with your CAM software.
The generator, the heart of the machine
The generator determines the cutting speed and the achievable surface finish. Ask for the stated minimum roughness (Ra) and whether the machine has an anti-electrolysis generator, which matters for carbide and titanium. Look at the fault history: a faulty power board can be expensive, and some parts are no longer made for older models. Note the number of sparking hours if displayed.
Dielectric and filtration
- Wire machine: deionised water, ion-exchange resin and filters. Check the displayed conductivity and the date of the last resin change.
- Sinker machine: dielectric oil, cleanliness of the work tank and reservoir, fire suppression system in working order.
- No leaks, corrosion or deposits in the tank or on the tables.
- Working chiller unit: temperature stability determines accuracy.
Mechanics and wear
On a wire machine, inspect the wire guides, power contacts, pulleys and the used-wire disposal system; test the automatic wire threader several times, including in a start hole. On a sinker machine, check the play in the head and the electrode changer. The axis linear scales must be clean and error-free.
The proof is in the part
Have a test part cut or eroded in a material similar to yours, with a finishing pass. Measure the dimensions, taper and roughness. A machine that holds its dimensions on a part lasting several hours is a good sign of thermal stability.
Running costs
Include wire, filters, resin, electrodes and energy in your calculation. Ask the manufacturer or its Swiss representative about the availability of parts and service, and about the cost of reconditioning the generator if needed.