Frequently Asked Questions
There is a wide range of power sources available and a major factor in the choice will be the mode of metal transfer: dip, spray or pulsed.
For thin section material, or welding in the vertical position, a low welding current is employed and the molten metal transferred to the workpiece by the wire dipping into the weld pool.
In spray metal transfer, the metal transfers in the form of a spray of fine droplets.
The pulsed mode of metal transfer is a means of achieving a spray type metal transfer at current levels below the threshold level. High current pulses, at a frequency of typically between 25 and 150Hz, spray used to detach dropletsas an alternative to dip transfer.
Fig.1. Voltage current output characteristics showing self-adjustment of the arc. V a=set arc voltage/arc length; V s=voltage at short arc length; V l=voltage at long arc length
Extracted from an article entitled 'Let's get technical - choosing an arc welding power source' by W Lucas and G Melton, published in Welding & Metal Fabrication, Vol.67, No.4, May 1999, pp.18-21. (Publishers - dmg BusinessMedia Ltd, Redhill, Surrey, UK - http://www.dmg.co.uk/dmgbm/ )
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