Before choosing a machine, it's worth checking what your workshop's consumer unit and incoming supply can actually handle, not just what socket is nearest the bench. Buying a three-phase-only machine for a single-phase workshop, or underestimating the load a higher-output single-phase welder places on existing wiring, are both avoidable problems with a bit of checking upfront.
The abrasive material itself matters as much as the shape. Discs formulated for steel typically contain aluminium oxide, while stainless steel usually calls for an inox-rated disc that's free from iron, sulphur and chlorine contaminants that could otherwise cause surface corrosion on the stainless. Aluminium and other soft, non-ferrous metals need their own dedicated abrasives too, since standard steel discs tend to clog quickly and produce a poor finish on softer materials.
Buying a first welder is easy to overthink. Rather than starting from a shortlist of machines, it helps to start from the work: what materials, what thickness, and how much of it will be done indoors versus outside or on-site. That single question narrows the choice between MIG, TIG and MMA far more usefully than comparing spec sheets in isolation, whether you end up looking at a Jasic entry-level MIG package or something further up the range.
Switching speed, the time the filter takes to darken once it detects an arc, is worth checking against how you actually work rather than assuming faster is always better for every budget. For most general fabrication and repair work, a mid-range auto-darkening helmet with a sensible shade range covers the vast majority of jobs comfortably.
If you're weighing up options for your own workshop, from portable units to fixed installations, it's worth talking through the layout with a supplier who stocks a range of systems, such as
tecproducts.co.uk.
The figure changes with output. Turn the amperage down and the duty cycle climbs, because the internal components are working less hard. This is why a welder can feel completely different in a busy production environment compared with occasional home workshop use: someone welding continuously through a shift needs a much higher duty cycle at their working amperage than someone doing short repair jobs a few times a week. It's the kind of spec worth comparing properly across brands such as Kemppi and EWM, not just reading off the headline amperage figure.