Zero Defect Press-Fit Assembly Enabled by Force Monitoring

Press fitting of bearings, bushings or shafts, for example in housings or gearboxes, can be monitored very accurately through the variation in the pressing force over the displacement. The characteristic nature of this force curve allows evaluation of the quality of process and tool. ControlMonitors from Kistler analyze the curve and decide whether or not the assembly is acceptable.

CoMo brand control monitors record the interdependent measurement variables of pressing force and displacement in pairs during the press-fit process. They display their functional relationship as shown in the diagram below and evaluate it at the end of the cycle.

Process evaluation

To reveal deviations from a reference part, a reference curve determined from an optimal press-fit process can be stored in the CoMo and shown in blue. The press-fit process is evaluated on the basis of thresholds, tolerance boxes and stop position windows. These objects can be almost freely defined in terms of position, size and type of evaluation (entry, exit and transit, minimum and maximum force, etc).

To obtain a part that is acceptable the measured curve must pass through the chosen evaluation objects as defined. Entry and exit sides are highlighted in green and the direction in which the curve passes through them shown by an arrow. Red limits must not be breached. A maximum of 12 evaluation objects may be freely combined.

Kistler Instrumente AG

Kistler’s core competence is the development, production and use of sensors for measuring pressure, force and acceleration. Kistler’s know-how and electronic systems can be used to prepare measuring signals for use in analyzing physical processes, controlling and optimizing industrial processes, improving product quality in manufacturing and improving performance in sports and rehabilitation

Kistler offers a comprehensive range of sensors and systems for engine development, automotive engineering, plastics and metal processing, installation technology and biomechanics.

A worldwide sales presence in the form of 18 group companies and 30 distributors ensures customer proximity, application support on an individual level and short lead times.

With a staff of 800, the Kistler Group is one of the world’s leading providers of dynamic measuring instrumentation. The Kistler Group achieved turnover of 174 million Swiss Francs in the 2006 financial year.