2.35.
Vernier height gauges and height masters rely to some extent on the skill of the operator
and are also relatively slow. A big advantage of the digital height gauge is that it provides an
immediate unambiguous digital readout of the measurement value. It is possible to hold this value
in memory and use as a datum for further readings, or be compared with given tolerances, etc. It
is also possible to provide a binary coded digit (BCD) output to enable the results to be further
statistically analysed and for a printout to be provided. These are provided with heavier steel or
granite bases with air-bearing floatation systems. Thus these provide a cushion of air between the
base of the stand and the surface plate which reduces, both the effort required to move the gauge
and the possibility of damage to the surface plate. The instrument can be zeroed at any position
after which it will display positive and negative dimensions with reference to the datum. There is
very fine adjustment facility and the slide can be securely clamped for marking out.
2.35.1.
Digital Height Gauge With Statistical Production Control.
Today’s modern
production techniques reflect a growing need for Statistical Process Control (SPC). Systems capable
of predicting or anticipating “out of tolerance” are thus of great value. The improvement in quality,
the reduction of scrap and the increase of efficiency in production capacity are all closely related.
Fig. 2.108
The digital height gauge with capability to provide SPC is best suited in this direction. Such a gauge
has following features.
— storage of upto 400 dimensions
— data retention on failure of electric power
— automatic entry of data as component is measured
— entry of data via the custom touch key-pad
— calculation of capability indices for quick and easy assessment of machine/plant or
process capability
— easy identification of component features out of tolerance
— calculation of mean, standard deviation and range
— assessment of 2-sigma, 3-signal, and 4-sigma confidence intervals
— comprehensive print-out of statistical data including histograms
— each sequence of measurement is recorded in numerical order and can be recalled
subsequently and printed out in the format required.
