Technical springs tested for demanding automotive tasks

>In order to provide guaranteed safety based on product dependability, Joos performs exhaustive testing of its springs so that they can withstand, for example, one billion load cycles with no damage when used in a diesel injection pump. Since springs must have the correct length in order to ensure a defined restoring force, Joos measures the length of its springs prior to delivery. Here the maXYmos BL force-displacement monitoring system from Kistler was chosen for use in a new sorting system.

>The maXYmos BL monitors and evaluates XY curves in which two measurands (force and displacement in this case) are required to exhibit a certain relationship with respect to one another. Using two switching thresholds and the UNI-BOX evaluation object, the maXYmos BL records the three possible states of the springs under test - spring too short, spring in tolerance and spring too long - and reports the result to the sorting chute via the PLC. Thanks to 100% testing of its springs, Joos can guarantee exact conformance with the customer's requirement profile, enabling consistent delivery and 100% quality assurance.

>Moreover, the compression springs must undergo mechanical processing in addition to testing. A grinding process ensures optimal faces for dependable bearing surface and also guarantees the exact spring length. The maXYmos BL also supports this process: based on threshold X for the defined force of approximately 0.5N, the monitor outputs the spring length at this point via its table of process values.

>The force of 0.5N defines the initial contact between the force sensor and the spring: the associated increase in force at this position thus precisely indicates the length of the spring under test. For managing director Jürgen Marx and head of quality management Dirk Retzlaff, the maXYmos BL has opened up a new range of test possibilities. Thanks to the 100% quality assurance, they can continue to satisfy the growing requirements imposed by the automotive industry for complete production monitoring, without increasing staffing levels.