AC pulsed MIG welding

TWI has recently installed an AC pulsed MIG welding robotic system.

This equipment which is believed to be the first of its kind in the UK is on loan from OTC Daihen Europe. The system comprises a CPDACA-200 power source, a DR controller and a DR4000 robot.

In the AC pulsed mode, both negative and positive polarity pulses are applied to the wire. This enables the relationship between welding current and wire feed speed to be varied.

On negative polarity the burn-off rate is greater and hence for a fixed deposition rate the welding current is reduced. This enables thinner materials to be welded than can traditionally be welded with the MIG process and largergaps to be bridged without burn through. The process can also be used for MIG brazing.

AC pulsed MIG is particularly suited to welding thin sheet materials as thin as 0.8mm and the equipment is pre-programmed for aluminium, carbon-manganese and stainless steels.

Because heat input is lower, distortion is reduced and also fume levels are claimed to be lower.

TWI has recently launched a Group Sponsored Project to investigate applications for the AC pulsed MIG welding process.

For more information contact Geoff Melton. E-mail: geoff.melton@twi.co.uk