Separating a piece of metal into two parts
If a piece of metal is too large for making a particular part then there are two possibilities. The unneeded bit can be machined away, for example, by turning it on the lathe or by milling part off using a milling machine. In both the cases the bit that was not needed is turned into swarf. Turning a piece of metal into swarf may be gratifying to the machinist but machining like this takes time and the metal machined off become worthless.
Time and money can be saved by finding ways of separating a piece of metal into two parts. This becomes a very common task because much metal is supplied in long lengths or large sheets and efficient ways to divide them up become necessary.
There are many ways of doing this. Which is the best for any particular job will depend upon the equipment available, the material being cut etc.
In many cases the separating process consists of two processes. Firstly the metal is separated but this leaves a finish that is unacceptable. This process, therefore, has to be followed by some means of finishing the edges. If only one piece is required immediately the other piece might be left in the unfinished state.
In many cases the two parts are separated along one or more straight lines which are simply determined to give the minimum necessary size to one part in order to make a specific component. In one special case the two parts might be separated by a round cut. This is trepanning. Another special case is where one part is pressed out of a larger piece of material.
Two parts may be separated by:
removing some material between them by
sawing by using
hacksaw
piercing saw
jigsaw
using a slitting saw or side and face cutter on the milling machine
hole cutter – trepanning
bandsaw
drilling
chain drilling
nibbling
removing material in the form of a circle – trepanning
using a drilling machine
on the lathe
on the milling machine
By melting or vapourising a strip of metal
using oxyacetylene cutting
using oxypropane cutting
using plasma cutting
laser
by shearing one piece of metal from the other
shearing on two sides at once
nibbling
punching
electrochemical etching
printed circuit boards
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