Institute for measurement and sensor technology

Mahr - OMS 443

The MarVision OMS 443 HA is a high-precision bridge-type multisensor coordinate measuring machine. It’s high accuracy, large measuring range in three dimensions and the variety of available sensors make it applicable for many measuring tasks. 

The machine base is made of fine-grained granite. The fixed bridge - of fine-grained granite as well – carries the quill. The laterally mobile measuring table with a glass pane can hold specimen up to 50 kg. All axes are driven by DC servo motors and are equipped with high precision backlash-free ball screws and precision air bearings on lapped granite guideways. This configuration allows for a high acceleration and a travel speed of 200 mm/s as well as very accurate measurements.

The machine has a large measuring range of 450 mm in x-direction, 400 mm in y-direction, and 300 mm in z-direction. The length measuring uncertainty according to VDI/VDE 2617 is E1 = (0.5 + L/900) μm or according to ISO 10360-2 it is E3 = (1.5 + L/500) μm. L describes the measuring length in mm.

The term “multisensor” describes the ability to measure both tactilely and – touch-free and fast – optically. The two sensor principles are combined on one measuring head.

An overview of the optical sensor technologies:

  • A system of two digital cameras and two magnification stages following a 10x object lens with a fixed focal distance allow the detection of edges and contours as well as contactless optical touching.
  • A coaxial incident light, a backlight for high contrast, and a four-segment ring light (all of them LED) can be either used individually or collectively to provide optimal illumination. 
  • A coaxially coupled laser focuses the camera’s field of vision and measures the depth of small bores, heights, contours, and shapes. 

The tactile sensor consists of mechanical touch-trigger probes based on strain-gauges. The Renishaw TP200 is a 6-way system with stylus changing rack and exchangeable stylus modules for different styli, ball diameter, and materials of the specimen.

The software used for operation and measurements is MarSoft Vision 3D.

The machine is installed in a climatic chamber solely equipped for this purpose. The temperature set to constantly 20 °C and the humidity to 50 %. 

Further developments of the system will be the integration of additional sensors such as an interferometrical white-light surface sensor and additional axes.

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