MACHINE TOOL TESTING
The accuracy of manufactured parts
depends on the accuracy of machine tools. The quality of work piece depends on
Rigidity and stiffness of machine tool and its components. Alignment of various
components in relation to one another Quality and accuracy of driving mechanism
and control devices.
can be classified into
If the alignment of the components of
the machine tool are checked under static conditions then the test are called
If the alignment tests are carried out
under dynamic loading condition. The accuracy of machine tools which cut metal
by removing chips is tested by two types of test namely.
o Geometrical tests
In this test, dimensions of components,
position of components and displacement of component relative to one another is
In these test, test pieces are machined
in the machines. The test pieces must be appropriate to the fundamental purpose
for which the machine has been designed.
Purpose of Machine Tool
The dimensions of any work piece, its
surface finishes and geometry depends on the accuracy of machine tool for its
manufacture. In mass production the various components produced should be of
high accuracy to be assembled on a non-sensitive basis. The increasing demand
for accurately machined components has led to improvement of geometric accuracy
of machine tools. For this purpose various checks on different components of
the machine tool are carried out.
Type of Geometrical
Checks on Machine Tools.
types of geometrical tests conducted on machine tools are as follows:
equi-distance and coincidence.
movements or squareness of straight line and plane.
spindle is to be tested for
of an axis.
Various tests conducted
on any Machine Tools
Test for level of installation of
machine tool in horizontal and vertical planes.
Test for flatness of machine bed and for
straightness and parallelism of bed ways on bearing surface.
Test for perpendicularity of guide ways
to other guide ways.
Test for true running of the main
spindle and its axial movements.
Test for parallelism of spindle axis to
guide ways or bearing surfaces.
Test for line of movement of various
members like spindle and table cross slides etc.
Use of Laser for
The alignment tests can be carried out
over greater distances and to a greater degree of accuracy using laser
Laser equipment produces real straight
line, whereas an alignment telescope provides an imaginary line that cannot be
seen in space.
This is important when it is necessary
to check number of components to a predetermined straight line. Particularly if
they are spaced relatively long distances apart, as in aircraft production and
Laser equipment can also be used for checking
flatness of machined surface by direct displacement. By using are optical
square in conjunction with laser equipment squareness can be checked with
reference to the laser base line.