| Basics of Coordinate Metrology Unit 7: Design of Coordinate Measuring Machines - Axes | Step 2 of 12 |
| The axes of the coordinate measuring machine control the positioning of the stylus system. The position of the stylus system is reported by the length measuring systems to the controller. The length measuring systems consist of measurement scales and scale readers. Apart from the precision of the guideways, bearings and drives, the obtainable measuring uncertainty of a coordinate measuring machine is affected in particular by the precision of the length measuring systems of the moving axes. The straightness of the guideways and the parallelism of the guiding mechanisms, relative to one another, are essential to the mechanical precision of the measuring machine, simply because they constitute the machine coordinate system. The most widely used guideways are air-bearing granite guideways. They have the advantage of being free of any sticking effect and capable of carrying large loads in static and dynamic operation. Owing to their high age, granite guideways exhibit long-term stability. Owing to their weight, they damp vibrations effectively. The air bearings provide a frictionless and no-contact axis movement. |
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 Ball screw | Continuously changing travel directions and travel speeds require sturdy drives of high speed range. The transmission of power from the drive to the moving component is effected by means of ball screws, friction wheels, belts, less frequently via toothed gears, their selection being determined by properties such as rigidity, dynamic behavior, slip, backlash, wear and friction. |