Latest News

Electronic dimensional gauging in hostile environments

Using electronic gauging probes for dimensional gauging of manufactured parts is a well-established quality assurance technique.

Typical gauging probes are cylinders with diameters of about 9mm and lengths ranging from 65mm to 100mm. They incorporate a non-contact inductive position sensor, either LVDT or half-bridge, which uses a spring-loaded movable armature coupled to a shaft that is supported in a high-precision linear bearing. They generally have a maximum gauging range of .25mm to 2.5 mm, with resolutions of fractions of a micron.

In hostile environments such as the shop floor, gauging probes can encounter serious problems. For example, the zero-clearance linear ball bearing must be protected from even the slightest contamination or it will jam up and fail. The thinness of the probe body makes it susceptible to accidental damage, which usually means replacement is necessary.

Many of the problems associated with dimensional gauging in hostile environments can be solved by Macrosensors’ GHS series of rugged and robust LVDT-based gauging probes, which are available from Bestech Australia.

These LVDTs feature a 19mm hermetically-sealed stainless steel probe with integral connector, a clearance-fit sleeve bearing, and gauging ranges up to ±25mm. The high accuracy of these LVDTs means that they are satisfactory for virtually any shop floor gauging function.

The sleeve bearing offers nearly the repeatability of a zero-clearance linear ball bearing, but is less susceptible to jamming. Some versions of the GHS series can be connected to a positive-pressure air stream to continuously purge the bearing space and prevent infiltration of contaminants. Also, the probe bodies are large enough to accommodate built-in sensor support electronics. This can reduce overall system cost by simplifying the gauging apparatus.

Send this to a friend