Heidenhain MT 25 Metro Length Gauges provide an 11uApp output and ± 0.5um accuracy. The MT 25/MT 25W/MT 25B plunger is extended via spring actuation, and the MT 25P is extended via pneumatic (air) actuation with a measuring length of 25mm for all.
The MT 25B 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 25/25W/25B Metro length gauges all work with a sliding guide. The sliding guides have these important properties:
· Sturdiness thanks to few moving parts
· Impervious to shock and vibration
· High plunger speeds and long service life thanks to high-quality ceramic bearings
· Less sensitivity to improper clamping
Pneumatic plunger actuation: The MT 25P length gauges are extended by the application of compressed air. When the air connection is ventilated, the integral spring retracts the plunger to a protected resting position. The gauging force can be adjusted to the measuring task through the level of air pressure. At constant pressure, it depends on the operating orientation and the plunger position.
Gauging Force: MT 25P
· Downward: (0.2 N/ 1.1 N)
· Upward: (0.2 N/0.9 N)
· Horizontal: (0.2 N/1.0 N)
The Heidenhain MT 25/MT 25W/ MT 25B come 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)
Operating orientation: MT 25/MT 25B/MT 25W
· Upward: 0.28-0.6 N/ 0.28-0.6 N/ 0.2-3.0 N
· Downward: 0.6-0.85 N/ 0.6-0.85 N/ 0.5-3.5 N
· Horizontal: 0.48-0.73 N/ 0.48-0.73 N/ 0.35-3.25 N
The plungers of the Heidenhain MT 25W Metro length gauges are protected by a rubber bellows. The bellows has high resistance to chemical and thermal influences, and have relatively no stiffness. There is little to no influence on the gauges mechanical behavior and measuring force.
Thermal dynamics: Heidenhain 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.
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.
