Omega Engineering GP901 - Manual (Page 5)

5 GP901 M-3343 05/08
Gauge Head Application Information
When mounting the Gauge Head in a fixture, care must be taken as the linear bearing assembly at the
tip end is made to very fine tolerances. If a high force is applied to the probe casing performance may be
affected. Ideally probes should be clamped in a yoke, split or collar clamp. If single point screw clamping
is adopted (see diagram), then a tightening torque (in Nm) should be limited to that which will give a
maximum of 50Kg point load. The Gauge Head may be mounted in any attitude.
where d = Screw dia. (mm)
P = Screw pitch (mm)
(assumes a V form thread and 0.15 coefficient of friction).
Typical maximum torque is 0.27 Nm (i.e. M5 x 0.8 steel or 10-32 UNF steel)
A clearance hole in the fixturing of 9.5 mm F is desirable around the gaiter for satisfactory operation.
Tip
Generally, where piece parts are automatically loaded into a fixture, or where there is the possibility of
severe side loads, the use of pneumatically operated transducers is strongly recommended.
To remove the tip, the shaft should be fully retracted into the body before unscrewing.
Pneumatic Gage Heads
The tip of a pneumatic Gage Head is normally biased in the inward direction and the extension of the tip is
achieved by applying air pressure to the Gauge Head nozzle.
Air pressure may be varied within the specified limits to achieve the desired tip force at zero. The
pneumatic Gage Heads are designed to be leak free and of small volume to minimise the air flow
requirements and maintain a consistent tip force. Care must be taken not to damage the gaiter seal as the
satisfactory operation of the Gage Head is entirely dependent on this component. A clearance hole in the
fixturing of 9.5 mm F is desirable around the gaiter for satisfactory operation.
To maximise working life of the Gage Heads the air supply should be both clean and dry for continual
reliable operation. Maximum relative humidity of 60 % RH and filtered to better than 5 µm particle size.
Environmental Considerations
Most Gage Heads are designed to be used with a gaiter and are designed to withstand the rigours of
in-process gauging and will operate satisfactorily in the presence of copious amounts of coolants and
cleaning solvents.
For Gage Heads without a gaiter such as Feather touch or in situations where removal of the gaiter is
necessary (i.e. at low temperatures where stiffening of the gaiter may be a problem) then the working
atmosphere must be both clean and dry. Ingress of dirt or fluids may interfere with the performance of the
probe or even cause damage.