− Machine the cores to separate pieces of mould steel and attach the piece to the mould assembly.

Explanation: The harder grades are used in automatic re-threading mechanisms and also if the machined shapes contain high flat surfaces. Hard wires resist change in direction and for that reason are likely to produce nice flat surfaces.

Explanation: Zinc coated wire is used in machining high melting point workpiece materials. The zinc coating vaporises in lower temperature than the brass core. Vaporisation reduces the amount of heat that transmits to the brass and the core wears less.

Explanation: The dielectric fluid in the die-sink EDM process is usually some petroleum product. In the wire cut EDM process, it is most common to use de-ionised water.

• Machining cores and corresponding fastening holes in the mould plates and inserts.

Explanation: It is important to harden the insert or mould plate steel before making the tightly tolerated ends in the ejector pin holes because the heat treatment tends to change the workpiece shapes at a certain degree.

Explanation: There is a need to cut the ejector to a right dimension and if the cavity surface is shaped there is also a need to shape the ejector end. The wire ED machine is one of the most accurate machines in mould shops and usually there is also free machining time available. Another option is to cut and shape the ejectors in a milling machine, but the most accurate milling machines are used in mould cavity machining operations and normally they are rather busy for long periods of time.

Explanation: The selection depends on the core dimensions and shapes. High and narrow cores or cores with sharp shapes are easiest to manufacture with separate parts. Special cases are core pins. Core pins are used in making small diameter holes to castings.

Explanation: Like every wall in the mould opening direction, the core walls are also drafted. It is rather difficult to make high drafted walls with a milling machine. Especially in the case of injection moulding or high pressure die casting moulds where the accuracy requirements are very high. The wire ED machine produces these shapes accurately with ease.

Explanation: Soft wires are useful in applications with complex shapes, where the machine changes the wire tilting angle several times. The harder grades are used in automatic re-threading mechanisms.