MacGregor Welding Systems (Mildenhall, UK) manufactures a wide range of micro-resistance and pulsed micro-arc equipment, which is used in the medical, aerospace and automotive industries to perform high reliability joining and interconnection of electronic components and subassemblies.

Recently, the company designed and built a fully automated machine to produce miniature sensor modules used in analysis equipment. The multi-stage process involves precision assembly of a number of small parts. Specific operations include the fitting and lubrication of O-rings, final molding insertion, and the welding of two strips of metallic ribbon onto a pair of small pins on a sensor module and connector block.

Central to the success of the machine has been a network of pneumatic and electrical actuators supplied by automation equipment manufacturer Festo Corp. (Hauppauge, NY). These include a pair of SLTE electrical mini slides and associated SFC-DC motor controllers for those parts of the system that require exceptionally high positional accuracy. Specifically, one of the mini slides is associated with initial product assembly, while the second plays an important role in the welding stage.

“We elected to use Festo SLTE mini slides primarily because they provide a complete, ready-to-run positioning solution,” says MacGregor Welding Systems managing director Graham MacGregor. “The slides incorporate their own miniature motors, which simplifies system integration and makes them very cost-effective…. The supplied control software is also extremely easy to use.”

Micro-resistance welding involves passing a short-duration, high-current pulse through the materials being joined, while accurately controlling an applied force. In the sensor application, the welding head module provides 10-millimeters of dynamic movement through the use of the SLTE mini slide. In addition, a compression transducer provides feedback to the control system, which triggers the welding power supply to deliver a pulse of current when the weld electrodes are in the correct position.

This welding technique requires far less thermal energy than a conventional soldering system, making it ideal for heat-sensitive components. It also provides a much faster means of securing consistent, high-integrity electrical connections. By employing the Festo slides, MacGregor was able to provide the precision necessary for a successful application in a compact system.

For more on automation and motion control, visit www.festo.com.

For more on automated assembly systems, visit www.macgregorsystems.com.