Phasa, which pioneered the Plastic Hot Air Stake Assembly process, has used a servo-based motion control system in place of a pneumatic actuator on its latest machines.

Essentially, the process involves selectively heating parts of thermoplastic mouldings using super-hot air, and then using cold tools to form, clamp and chill the parts into their required shapes. The resultant assemblies are strong, tight and stable. Applications for these fixings are diverse and include the automotive, electrical/electronics and white goods industries.

The company manufactures standard and custom machines to automate the entire assembly process – from inserting the thermoplastic mouldings into the components being joined, to selectively heating, forming and cooling them.

The new servo system provides the main movement of assembly nests. Of benefit, by using closed-loop control it is capable of fully programmable multi-stop positioning, resulting in faster and more accurate placement of the assembly nest.

In this case, Phasa chose a complete Festo assembly comprising a toothed belt axis, servomotor, gearbox and servo motor controller to provide the horizontal movement of the assembly nest platen on its large 40/80 machine. The servo controller is networked to the 40/80 machine’s host PLC. Compared to the all-pneumatic version of the machine, the electric servo based model accomplishes the same assembly operation in 33 seconds, improving throughput by nearly 6%.

In addition to programming flexibility, the CMM-AS servo controller offers a particular benefit for this application. Terry Elvidge, Phasa’s operations director, said: “A further advantage of using Festo servo drives is that they facilitate the capture of timed process parameters for every part made. This is vital to our customers’ quality management procedures, enabling the data to be networked to a central server system and logged against the barcode for that particular part, providing a complete manufacturing record.”

Phasa is now also looking at incorporating electric servos in a number of its smaller machines.


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