Smooth movement in sensor test rigs

Initially, this work and the quality assurance testing were done manually. However, as the number of products grew, the time and labor required increased, as did the demands on quality inspection. The company developed a test cell where the test processes are automated. A SCARA robot is used to move the sensors from electrical to optical testing. Another robot removes the parts from the line every ten seconds and sorts them into the groups "faultless" and "faulty". Hoffmann + Krippner have set up two of these inspection lines, each of which inspects one million sensors per year.

A suitable driven linear actuator including control system was required for the feed to the visual inspection station. The actuator had to be durable and maintenance-free, and the control system had to be intuitive.

A pneumatic solution, which was initially considered, was rejected for cost reasons.

Our toothed belt actuators from the drylin ZLW series in conjunction with the drylin W pillow block WJ200UMA fulfilled all customer requirements. Unlike conventional rolling bearings, which have to be lubricated, igus bearing technology does not require lubrication or maintenance. The sliding element of the pillow block is made of the robust material iglidur J200, which offers a very good coefficient of friction even at low loads. In the event of wear, the bearing can be replaced on the rail without disassembly.

With this linear unit, Hoffmann + Krippner has found a solution that is easy to install and standardized. The clearance height of the drylin ZLW-1040 is only 45mm, the stroke length is variable, and the suitable carriages are supplied in three different sizes. Initial tests were carried out on a toothed belt actuators with a stroke length of 150mm, although, the company later also installed a unit with a longer stroke. The linear module was provided ready for connection with a powerful stepper motor in installation size NEMA 23. A drylin D1 motor control system for stepper, DC and EC/BLDC motors is also used. The customer is pleased that the control system is absolutely identical and completely independent of the length of the unit.

Finally, another igus product helps ensure that the two test lines can run smoothly: the moving cables on the robot are safely guided by a modular e-chain®, which is easy to install and can be opened and filled quickly if required.