1. UNIVERSAL
MEASURING
MACHINE
DHARMASASTHA N,
CIPET-CHENNAI.

2. ESSENTIAL COMPONENTS
 Length
 Geometry
 Division of circle
 Roundness

5. Comparison of CMM & UMM
CMM UMM
It is useful for rapid
inspection of production
parts.
It does not inspect that
much fast.
It does not inspect
Geometric features of the
part.
But UMM does it.
It is not accurate. It is more accurate than
CMM.
Reveals the failure but not
reason.
UMM useful in this regard.
It is useful for Quality control. It is capable of resolving the
exact nature of the error of
all part features, regardless
of complexity.

6. INSPECTION ON UMM
 Essential that the work piece should be
mounted carefully on UMM.
 Measuring the location of hole.
 Measuring of awkward shaped work
pieces.
 Use of Microscopes for measuring small
size holes.

7. MECHANICAL ACCURACY
 Attainment of “cubic concept” of
accuracy in the UMM requires the
individual mastery of four mechanical
arts- Geometry, Length, Dividing of
Circles and Roundness.
 These are truly the “Foundations of
Mechanical Accuracy”.

8. Geometry
 Flat plane.
 Meehante cast iron(close grained).
 Elastic deformation-minimised-design and
support.
 Temperature differentials affects the
accuracy.
 Localized heating and cooling causes
unpredictable distortion.

9. Standards of Length
 Internationally acceptable standards.
 Accuracy of derived length-standards
such as gauge blocks, precision scales,
step gauges, lead screws, and laser
interferometer depends in large measure
on how truthfully they represent the
ultimate length standard.

10. Dividing the Circle
 Authority of “angles” of angle gauges,
rotary tables, or the angular relationships
in mechanical parts and assemblies is
derived from the self-proving principle of
dividing the circle

11. Roundness
 Precision machine tools must achieve
roundness and especially with their
spindles.
 Location, effective size and fit between
mating parts are all dependent on the
ability to measure and define the
conditions of roundness.