Application of interest
Pressing to a Depth Relative to a Part Feature
Motor Assembly – SCHMIDT® Application 4189
Schmidt Technology was asked to design a pressing station to assemble a magnet onto the shaft of a motor assembly. The application required the magnet to be pressed onto the shaft of a motor assembly such that the top surface of the magnet is within +/-0.12 mm from the top of a PCB that is soldered onto the motor housing (see picture above). The shaft was to be support on the opposing side to prevent bearing damage within the motor and no force greater than 9 N could be applied to any area of the PCB. Additional requirements included a pressing force in excess of 670 N, a cycle rate of less than 6 seconds and assurance that the interference fit between the magnet and shaft were within their specification.
With a component tolerance stack-up of more than +/- 1 mm for the entire assembly and the above requirements, conventional wisdom would be to use a fully controlled ServoPress system, but our solution was much simpler and cost effective.
We selected a Nr. 20.100.2 Direct Acting Air Press with PRC-50D-1 control, Schmidt SpeedControl, PM9310 monitoring package and designed a custom press tool that incorporated a light spring loaded probe and sensor.
For the operation, the operator loads the magnet into the bottom of the nest and the motor assembly into the nest, above the magnet. The operator initiates the cycle and the press ram extends at full speed, pressing the magnet onto the shaft. At a predetermined height, approximately 2 mm above the final pressing height, the speed control engages to slow the ram speed to a controlled rate. During this controlled stroke, the spring loaded probe contacts a non-populated section of the circuit and is pushed into the tooling until it triggers a sensor. The sensor input is what initiates ram retraction.
The results of this approach produced a machine that achieves a final assembly tolerance of +/-0.05 mm, a cycle rate of approximately 4 seconds and provides 100% quality control.
See other interesting applications at www.schmidtpresses.com/products/presses/7appFliers/qFliers.cfm
Tip of the Month
With our customer base spreading their manufacturing out to different parts of the world, Schmidt Technology has been striving to maintain a presence for sales, service and support across the globe, including sales offices in Asia and Africa. In order to serve our more regional customers better, Schmidt Technology Corp has expanded it coverage to include Central and South America. We are currently working on establishing representation in Brazil and Argentina and will be increasing this coverage to all of the Americas.