Heidenhain MT12 Metro Length Gauges provide 1Vpp output, the MT 12 is in the extended position via a spring at rest while the MT 12P is retracted and extended by pneumatic (air) air push. The MT 12 are equipped with either a sliding guide or a ball-bush guide is opting for the MT 12B.
Metro length gauges are designed with ball-bush guides. The following are some of the basic properties of ball-bush guides in HEIDENHAIN length gauges: Low friction, which makes versions of length gauges with reduced gauging force possible. Safe plunger extension and retraction even with high radial force. High precision of the measuring loop thanks to a guide that is free of play (the bearing and plunger are specially fitted during manufacture).
The Heidenhain MT 12 Metro comes with a built in spring that extends the plunger to the measuring position and produces the gauging force. While at rest the plunger is extended. The gauging force depends on the following criteria:
· Operating orientation
· Plunger position (the force changes over the course of the measuring range)
· The direction of measurement (whether extension or retraction of the plunger is used)
If opting for the MT 12 P Metro with Pneumatic Plunger Actuation the gauge with be extended by the application of compressed air. When the air is ventilated out the plunger retracts back to its protected resting position. The gauging force can be adjusted as needed through the level of air pressure used.
· The operating orientation (0.02 N, 1.1 N)
· The plunger position (can be adjusted through the air pressure level)
· The direction of the measurement (whether extension or retraction of the plunger is used)
Thermal dynamics: Heidenhain MT 12 length gauges have a defined thermal behavior. Since temperatures can vary during the measurement process and possibly cause a measuring loop, Heidenhain uses special low coefficient of expansion material for the components of the measuring loop. The Heidenhain MT 12 has IP 50 Protection.
Repeatability: Whereas the system accuracy applies over the entire measuring range, for some applications the reliability is the decisive factor. It plays an important role in repeated measurements. The repeatability of the length gauges is usually better than the values listed by Heidenhain. Reliability depends on the combination of materials used in the components, installed electronics, optomechanics used, and the bearing of the plunger.