Using its extensive pneumatics knowledge and experience, European automation specialist Festo helped develop a new handling system for ultrasonic welding manufacturer Herfurth UK Ltd. The Luton-based company is to supply its innovative precision bumper welding system to the prime contractor of a global car manufacturer.

Herfurth UK is an industry-renowned manufacturer of specialist ultrasonic welding equipment, and the only company manufacturing these advanced systems in Britain. The new machine, developed with pneumatics expertise from Festo, incorporates new-generation pneumatic handling equipment for maximum performance at low cost. It performs ultrasonic ‘staking’ to secure various moulded subassemblies into the final bumper form.

The state-of-the-art system uses high-quality components in 39 ultrasonic heads to activate seventy weld points on the bumper assembly. It uses Herfurth’s proprietary ultrasonic switching unit, enabling several welding transducers to be operated from one or more generators. The machine is designed to run for 20 hours per day for two to three years – based on the expected life of the given vehicle bumper before being superseded by a facelift variant. In addition, it is likely to continue operating after this time producing spare bumpers.

Festo’s HMP range of cylinders, designed expressly for handling applications, was specified in the load and unload stages of the bumper assembly. These units feature a robust integral guide, giving a powerful but controllable interconnection between the X and Z axes. Servo-pneumatic controllers drive the load frames accurately into position; these devices offer precision control over end positions, velocity and motion profile. The welding machine also uses a Fieldbus system to dramatically reduce the amount of wiring, with the specification also calling for integration to a Siemens PLC. With the Profibus implementation, interfacing was straightforward, thanks to existing corporate collaboration between Festo and Siemens.

Herfurth had used Festo equipment in previous applications and was considering the use of Festo’s pneumatic products in the weld head drivers. While scrutinising the overall design, the Festo consultant recommended also using pneumatics for the handling stages, based on the exceptional mechanical integrity of the company’s new HMP handling range. Although it seemed an unorthodox application of pneumatics, Herfurth’s design team was finally convinced of the viability of the process and was happy to benefit from significantly lower costs than servo-electric solutions. The result was the evolution of Herfurth’s new bumper welding machine, with collaboration from Festo to help achieve a ‘right first time’ solution.

Colin Coles, Design Manager at Herfurth comments: "The new technologies used in the machine were all new departures for us, but everything went well; the wiring was simple; ‘clipping’ on the modules was easy; we used a contractor to programme the PLC software and that proved to be straightforward; and the final machine looks very clean in its design. We are very pleased with the outcome”.

Asked about the future for automation options at Herfurth, Coles says: “Pneumatic pick & place handling now offers our customers and us a real alternative to electrical servo-driven robot solutions. It gives the same levels of control in positioning, speed and motion profile but without the complexity and cost. We were, in fact, able to reduce the cost over all other solutions we had investigated. It was a team effort that resulted in a fully integrated solution, and I anticipate that we’ll be using more of this technology.”

Further information can be obtained from:

Festo Ltd
- Addr: Automation House, Harvest Crescent, Fleet, Hampshire, GU13 8XP , UK
- Contact: Nicola Street
- Tel: 01252 775000
- Fax: 01252 775001
- WWW: http://www.festo.com
- Email.