Macrosensors GHS series LVDT-based gauging probes

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 9 mm and lengths ranging from 65 to 100 mm. 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 0.25 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.

The Macrosensors GHS series rugged and robust LVDT-based gauging probes feature a 19 mm hermetically sealed stainless steel probe with integral connector, a clearance-fit sleeve bearing and gauging ranges up to ±25 mm.

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.