Rotationally symmetrical parts are used in the construction of motor vehicles (especially in engines and transmissions), in the watch- and clockmaking industry, and in other branches of industry. Where relatively simply structured components manufactured by turning or grinding operations were formerly used, today increasingly complex contours are produced through a combination of manufacturing processes. High requirements for quality standards
necessitate in-process quality control.

One typical example of this is the production control of camshafts and crankshafts for motor vehicle engines where a variety of different measuring tasks are combined. In order to perform a complete measurement in a single clamping action, a multisensor coordinate measuring machine is required. Due to the close run-out tolerances of the seats of the rolling bearings, maximum precision is necessary. All diameters, undercuts, grooves and run-out tolerances can be measured without contacting the workpiece using the image processing sensor. A measuring probing system or laser distance sensor is suitable for measuring the form, and measurements of axial run-out can be performed with tactile probes. This also applies to the measurement of cooling bores in the shaft.

The manufacture of different shafts in the same production line requires an extremely flexible measuring machine. Modules for measuring recurrent geometric features such as the cam contour, the bearing concentricity, the width of land, etc. are combined to form a single parameter program. The user can thus line up the individual modules of the measurement plan to match the design of the shaft and enter the corresponding parameters. Time-consuming, detailed programming of large numbers of individual features can thus be omitted. The results are displayed both graphically and numerically in a form suitable to the user’s needs.

Fig. 63: Measurement of vertically clamped camshaft: The measurement record also includes a graphic representation of the camshaft error.

It is advisable to clamp larger shafts in a vertical position for measurement (Fig. 63) in order to prevent deflection of the shaft and any resulting additional errors in measurement. This applies especially to the measurement of extremely complex crankshafts.

Precision shafts like the ones used in clocks and watches are measured together with their corresponding gearwheels and threads. Parametric programs are also used for this purpose. The high precision of the machines used to perform measurements like these enables the inspection of diameter tolerances of only several micrometers.