Testing Machine Tools

Testing Machine Tools

Testing Machine Tools - The name of Dr. G. Schlesinger has for many years been linked with the subject of machine tool tests and alignments. Many years ago he established certain acceptance tests and tolerances in Germany for machine tools which were to be supplied to Russia under contract.

In later years, as Director of Research for the Institution of production Engineers, Dr. Schlesinger was instrumental in getting that institution, jointly with the Institution of Mechanical Engineers, to publish charts containing tests and tolerances for a number of machine tools.

After manufacture, erection, repairs or overhaul each machine tool must be tested as per accuracy test chart in order to check whether it meets the requirement of specification or not.

Machine tools are tested for:

1. The grade of manufacturing accuracy i.e, the accuracy with which tbe machine tool has been assembled. This is known as the Geometric test or Alignment test and consists of checking the relationship between various elements when the machine tool is idle and unloaded.

2. The second test is known as Practical test or Performance test and consists of checking the accuracy of the finished components. This test is performed after one hour of trial run so that spindles get sufficiently warmed up.

The Acceptance Test of machine tools includes both Alignment test and Performance test. According to approved general specifications, acceptance tests of machine tools should include:

(i) Idle run tests, mechanisms operation checks, certificate data checks,

(ii) Load tests and productive output tests,

iii) Checks of the geometrical accuracy, surface roughness, and accuracy of the workpieces being machined,

(iv) Rigidity tests of machine tools,

(v) Tests for vibration proof properties of machine tools in cutting.

In general, these tests should be carried out at the manufacturer's works because skilled persons will be available together with the necessary testing equipment which will not be obtainable at the user's end.

Moreover, it is hardly possible for the machine tool manufacturer to assume the responsibility for the consequences of treatment to which machine tools are subjected whilst being transported from the works to their destination.

As explained above also, performance tests check the accuracy of the finished component, whilst the geometrical tests cover the manufacturing accuracy of the machine tool. Both tests are practical and both form part of one indivisible whole. Neither the user nor the manufacturer can dispense with either of these tests.