Share EDM aka Electric Discharge Machining - Plastic Mould Making

Thu Apr 20 00:46:27 CST 2023

Once an incredible black art in mould making, EDM has evolved into a highly complex and predictable process. Powerful software, highly accurate positioning mechanisms, advanced dielectric oils and specially developed electrode materials combine to make EDM the workhorse of any injection mould manufacturing process.

The traditional method of the mould maker designing and manufacturing each electrode for the entire mould has disappeared with the new approach. Today's graphite, copper or copper/tungsten electrodes are produced in high-end CNC machining centres specially designed for this purpose.

EDM is non-contact machiningPlastic moulds

Instead of direct contact between the tool electrode and the workpiece, there is a spark discharge gap, usually between 0.05 and 0.3 mm, sometimes up to 0.5 mm or even larger, which is filled with working fluid and which is discharged by high voltage pulses to erode the workpiece during machining.

It is possible to "overcome the rigid with the soft"

Since EDM uses electrical and thermal energy directly to remove metal materials, it has little to do with the strength and hardness of the workpiece material, so it is possible to use soft tool electrodes to machine hard workpieces, thus "overcoming the rigid with the soft".

Any difficult metal or conductive material can be machined

The machinability of the material depends mainly on its electrical and thermal properties, such as melting point, boiling point, specific heat capacity, thermal conductivity, resistivity, etc., and is almost independent of its mechanical properties (hardness, strength, etc.). This makes it possible to break through the limitations of conventional cutting tools and to machine hard and tough workpieces with soft tools and even superhard materials such as polycrystalline diamond and cubic boron nitride.

Complex surface shapes can be machined

Because the shape of the tool electrode can be simply copied onto the workpiece, it is particularly suitable for machining complex surface shapes, such as complex cavity moulds. In particular, the use of CNC technology has made it possible to machine complex shaped parts with simple electrodes.

Parts with special requirements can be machined

Parts with special requirements such as thin-walled, elastic, low stiffness, micro-fine holes, shaped small holes and deep small holes can be processed, as well as fine text on moulds. Since the tool electrode and the workpiece are not in direct contact during processing, there is no mechanical machining cutting force, so it is suitable for processing low stiffness workpieces and microfabrication.