Plasma Cutting Explained: What To Consider Before You Invest

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 TEC Products.

Plasma cutting uses a jet of ionised gas, usually compressed air, forced through a nozzle at high speed and heated by an electric arc to a temperature hot enough to melt through electrically conductive metal. The molten material is then blown clear by the same jet, leaving a narrow, clean cut. Unlike oxy-fuel cutting, plasma works on any conductive metal, including stainless steel and aluminium, not just carbon steel. Hypertherm is the plasma cutting brand we get asked about most, and it's worth understanding the basics before comparing specific units.

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.

Ambient temperature and airflow around the machine also affect real-world performance. A welder working in a hot, poorly ventilated space, or one that's been boxed in against a wall with no clearance for its cooling fan, will hit thermal cut-out sooner than the same machine used with proper clearance in a cooler environment. Keeping vents clear and giving the unit room to breathe protects both the duty cycle you paid for and the components inside.

Duty cycle is one of the most misunderstood figures on a welder's spec sheet, yet it tells you more about real-world usability than the headline amperage does. It's expressed as a percentage over a ten-minute period at a given output, so a machine rated at 30% duty cycle at its maximum amperage can run for three minutes out of every ten at that setting before it needs to rest and cool.

A welding table is easy to overlook when planning a workshop, yet a poor one undermines accuracy on every job that touches it. If the surface isn't flat, nothing clamped or squared against it will be either, and small errors compound quickly on anything with multiple joints or angles.