Spark erosion
From Wikipedia, the free encyclopedia
Spark erosion is a machining process that is particularly used in the making of plastics moulding tools. Instead of using grinding or cutting processes, spark erosion simply involves the slow lowering of a shape (often in copper or graphite) onto the metal (usually steel), which is immersed in paraffin oil, with a voltage applied between the two. Constant sparking over a period of hours erodes the metal away, leaving a very precise shape.
Spark erosion is particularly useful because it allows awkward shapes to be formed. For example, a square hole is easily made in a block of steel by lowering a square tool onto it. It can also be used on pre-hardened steel moulds, or to modify moulding tools that have been hardened without the need for heat treatment to soften and re-harden them.
[edit] Advantages
This is a much faster way of producing a die compared to hand making one.
[edit] Disadvantages
Leaves many spall indentations on the the mould which in turn produce many small indentations on the final product. This gives it a matt effect as against a shiny smooth surface. There are advantages to thus though. It allows the manufacturer to hide any small deffects and also will stay cleaner in the long run.
