Average Indicating Instrument with Interchangeable
Pickups and Alternate Drive Units
The instrument selected to typify this group (Fig. 15-9)
represents the repeatedly improved model, with substantially extended capabilities,
of an original that may be considered the prototype of stylus using
average-roughness measuring instruments. This historical background, although
barely recognizable in the exterior appearance and engineering characteristics
of the present-day instrument, still persists in two significant respects: (a)
The basic principle of measurement by the conversion of
surface-roughness-caused stylus excursions into proportional electrical
signals, and (b) the trade name Profilometer that, in this country’s technical
language, is widely associated with the general method of stylus type
surface-roughness measurement.
The illustrated group of units is one of several
alternative combinations, yet it is typical enough to represent the principles
of this category of instruments.
Fig. 15-9. Surface roughness
measuring instrument with digital display, built-in memory and PC connectivity.
Fig. 15-10. Surface
roughness measuring instrument with processor control module.
Modern devices like those pictured in Figs. 15-9 and
15-10 contain four principle elements:
a. A stylus lift mechanism which allows for approximately 2
inches of vertical adjustment and rotation of the pick-up to a variety of
measuring positions, including right angle and inverted. This feature allows
for the time-saving gaging of parts without the need for additional fixturing.
b. Built-in memory/storage allows for the digital
display of individual amplified readings and portable
storage of up to 100 separate measurements. These measurements can be
downloaded to a PC or printer as may be convenient.
c. A comprehensive range of pick-ups and accessories are available
to accommodate a variety of parts features (e.g., small bores, grooves, sharp
edges, curved gear teeth, recesses and rougher surfaces). d. Powerful software
options are made possible via the RS232 connectivity of the surface roughness
gaging instrument to a PC. The software itself allows for the display of
visually advanced images thereby clarifying the recorded information as it is
analyzed.
The instrument shown in Fig. 15-10 goes a step further by
including a wireless processor control module. Equipped with a color VGA touch
screen panel, the operator can set inspection parameters, control the measuring
device and instantly receive graphically displayed information. This
information can of course be transferred to PC for storage of further analysis.
Surface Analyzing
Instrument with Computerized
Recorder for Multiple Characteristics
The instrument group shown in Fig. 15-11 comprises members
that were designed with particular emphasis on the analyzing, visual display
and recording capabilities of the system. The probe pickup, which is of a
breakaway design to eliminate damage, has full measurement capability including
skid support for average-roughness sensing, or it can be externally referenced
by being supported on a cantilever arm that is precisely guided inside the
drive unit.
A personal computer utilizing an advanced surface metrology
program allows the operator to visualize surface measurements. Hard-copy
records of measurement data can be outputted to either a standard printer or the
system’s own data acquisition controller unit printer/recorder. This system
offers complete analysis of all forms of profiles, roughness and waviness,
including all combinations thereof.
Fig. 15-11. Surface-analyzing
instrument (T8000) designed for comprehensive analysis, visualization and hard
copy recording of surface texture by exploring various surface parameters such
as roughness average and waviness.
Integrated Measurement of Dimension, Form and Texture
on Curved Surfaces
Most surfaces encountered have four measurable elements of
interest, namely: dimension, form, roughness and waviness. The simultaneous
measurement of these elements is possible with just a single traverse of the
stylus across the curved or straight feature being measured (see Fig. 15-12).
This skidless device has only the stylus coming in contact with the part
thereby allowing for unfiltered feature measurements which in-turn makes the
data collected suitable for an advanced and integrated analysis. The device
shown in Fig. 15-12 is in contact with a high precision spherical artifact used
for the purposes of calibration and correlation. Calibration over the ball
checks stylus condition, gage range, linearity and processor functions. Once
properly calibrated, data gathered may be viewed using the processor control
module previously shown in Fig. 15-10 or downloaded to a PC for analysis using
sophisticated software.
Fig. 15-12. “Form Talysurf
Intra” measuring instrument.