High accuracy length gauge for use in harsh environments

A new, incremental length gauge for high precision measuring and in-process control applications in harsh environments has been introduced by Heidenhain. It is ideal for use in the working area of grinding machines, lathes and other metal-cutting machine tools and produces results accurate to ±1µm over its 30mm measuring range. The device is called SPECTO ST 3087RC, and has a special housing to protect its precision mechanism. A built-in spring keeps the plunger, surrounded by a rubber bellows, retracted behind a guard and splash cap when the gauge is in its rest position. Extension of the plunger to the measuring position is actuated by compressed air, normally with the coolant switched off. A significant increase in productivity and a reduction in floor-to-floor time result from not having to transfer components to a measuring station external to the machine tool, or to a quality control department. Should rework be necessary after metrology functions have been completed, in-process gauging preserves accuracy by eliminating the need to set the component up again for a second operation. The device has an IP rating of 67, so it is totally protected against ingress of dust and is unaffected by high pressure coolant jets and even short periods of immersion. It is also tolerant to extremes of temperature, vibration and shock. The 1 VPP interface opens up many possibilities for feedback to a machine tool control, as well as for logging measured results and processing them for statistical analysis.