go to the home page

go to the page above this one

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


piercing saw


using a slitting saw or side and face cutter on the milling machine

hole cutter – trepanning



chain drilling


removing material in the form of a circle – trepanning

using a drilling machine

on the lathe

on the milling machine

parting on the lathe

By melting or vapourising a strip of metal

using oxyacetylene cutting

using oxypropane cutting

using plasma cutting


by shearing one piece of metal from the other

guillotining, shearing

shearing on two sides at once



electrochemical etching

printed circuit boards

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: