Molybdenum wire cutting machines offer many advantages over conventional brass wire cutting machines.
The molybdenum wire diameter commonly used is 0.18mm which meets most design requirements of narrow cuts and near sharp inside corner radii. The 0.18mm size has been found to give a perfect balance between lifetime, cutting speed, cutting tolerance and surface quality.
Because of its high tensile strength, molybdenum wire aids in maintaining excellent wall straightness whilst reducing the number of wire breakages common with copper or brass wires.
In special cases, typically in medical and military applications, there must be no copper or zinc contamination of the wire cut surface. These criteria eliminate the use of copper-based wires and facilitate the use of molybdenum or tungsten wires.
In contrast to copper (Tensile strength 200-250MPa) or brass wires (Soft tensile strength +/-375MPa and Hard tensile strength +/-1180MPa), molybdenum wire has a very high tensile strength of +/-1725MPa. Molybdenum wire is therefore more resistant to very high pulling forces.
This gives several advantages:
- Reduced wire breakage.
- Reduced elongation (<2%) of the wire during cutting.
- A higher pulling force guarantees straighter cuts in that the wire better resists side forces with less deformation in angular cutting movements. This allows very precise straight side detail with sharp definition.
- Due to the higher pulling force the cutting speed of the wire can be increased for higher productivity.
Because molybdenum wire has a very high melting temperature (2625oC) compared to copper (1085oC) and brass (900-940oC) molybdenum wire CNC cutting machines are designed to handle very high working temperatures, with the result that almost all conductive materials – including the hardest and the toughest – can be cut successfully. Normal grade steels can be cut faster due to the use of higher spark power per second and per length of wire used compared to normal wires.
The spark craters left on the wire surface are very small compared to those left on the workpiece after cutting, resulting in much longer wire life than softer wires. On the other hand, the sparks produced on the workpiece are much bigger and give a better and faster cutting result. The metal removal rate can be very high with an electrical discharge machine (EDM) correctly designed to quickly flush away the burnt metal particles from the cut.
Typical molybdenum EDM parameters are given below:
Worktable size: 350mm x 600mm.
Cutting axis: 320mm (X) x 400mm (Y) x 400mm (Z).
Maximum weight of workpiece: 300kg.
Maximum machining speed: 170mm/min.
Wire diameter: 0.10 – 0.20mm.
Cutting tolerance: +/-0.015mm.
Surface finish: Ra <=1.2mm.
Power supply: 380V 3 phase.
Power consumption: 2.5KW.
NOCKERS ENGINEERING PRODUCTS stock 0.18mm diameter molybdenum cutting wire on 2000m vacuum packed plastic spools.