Tsuneo Mita

Spatter reduction - power source considerations

(1991). Spatter reduction - power source considerations. Welding International: Vol. 5, No. 11, pp. 847-850.

Mechanism of welding fume suppression during AC-pulsed MIG welding of Al–Mg alloys

Summary Welding fume, inevitably generated during arc welding processes, may be a source of occupational pneumoconiosis when persistently inhaled in the long term and accordingly merits serious consideration in occupational hygiene respects. To improve the working environment at welding sites, it is imperative to ensure total air exchange at work sites, local extraction in the vicinity of welding facilities, and the wearing of respiration protection devices in other respects.1 Currently available preventive measures, however, suffer from a number of drawbacks, such as heavy investments needing to be made in equipment and facilities and operability being obstructed by the wearing of respiration protection devices. Alongside such passive measures, it is desirable to develop welding materials or methods able to suppress welding fume generation at source.

Pulse mig welding of aluminium using constant voltage characteristic power source

The adoption of the synergic (1 pulse 1 droplet transfer) pulse welding process developed in the early 1980s facilitated the achievement of a stable arc state over a wide welding current range by setting relatively simple pulse parameters; consequently, the workability of pulse MIG/MAG welding was substantially improved. In addition, the introduction of the inverter control system for welding power sources from the mid-1980s led to the attainment of high speed/high accuracy control of the output current/voltage; in addition, analysis/ research on arc/welding phenomena has been significantly progressed and novel output control methods for welding sources have been successively developed. Examples are, pulse current rate control-, current compensating control during short circuits, low frequency pulse superimposition control and alternating current pulse control or alternating current/direct current composite control; various developments leading to high function and high performance have been promoted. In a common pulse MIG/MAG welding power source, droplet transfer control employs a relatively easy constant current characteristic; however, this paper describes in outline and gives the characteristics of a standard pulse MIG welding (1 pulse 1 droplet transfer welding) of pulse MIG/MAG welding power source which takes best advantage of the constant voltage characteristic and low current pulse welding (2 pulses 1 droplet transfer welding) developed in recent years, mainly for aluminium sheet.

Problems of arc welding technologies

In keeping with the progress and development of power semiconductor technology and electronic control technology over recent years, output control systems for the welding power unit have also advanced from thyristorcontrol to transistor-chopping-control and then to inverter-control. This has enhanced the speed and precision of output control. As a result, the output control techniques have been applied to finer and more detailed areas, and hence the welding power devices developed have achieved higher performance and function and become able to perform finer control of arc welding phenomena. In this article, a report is made of some representative control methods of welding phenomena and their characteristics as examples to show the recent progress in arc welding techniques.