What's inside
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What “1/2-inch capacity” really means
For a fabrication shop, a cutter that can sever 1/2-inch steel is not necessarily a cutter that will make clean, production-ready cuts through it all day. Manufacturers often distinguish between recommended cut, maximum cut, and severance capacity. Maximum or severance ratings usually mean the machine can get through the plate under favorable conditions, not that it will leave a square edge at a useful speed.
For regular work on 1/2-inch mild steel, look for a machine with a rated cut capacity around 5/8 inch or more, and check that rating at the input voltage you can actually supply. That gives the cutter some reserve instead of forcing it to run at its limit. If half-inch plate is occasional work, a lower-capacity unit may be adequate, but expect slower travel, more dross, and less room for imperfect technique.
Power supply and duty cycle matter
Many cutters suitable for this work need 240-volt single-phase power and a circuit sized to the manufacturer’s instructions. Some dual-voltage machines also run on 120 volts, but their output and cutting capacity generally drop on that supply. A machine advertised with a high maximum capacity may not deliver it from a standard household outlet. Confirm the input current, breaker requirements, plug, and extension-cord guidance before buying.
Duty cycle tells you how long the machine can cut within a ten-minute period at a stated output. A 40% duty cycle means about four minutes of arc time followed by six minutes of cooling at that rating. It does not mean four minutes of continuous production is always practical: setup, repositioning, and cuts at lower output affect real work. If you routinely cut long parts or batches of plate, favor a stronger duty cycle at the amperage you’ll use.
Cutter types worth considering
A conventional 240-volt inverter plasma cutter is the practical choice for most shops. It balances capacity, portability, and cost. Compare machines by their rated capacity and duty cycle at a specified amperage, not just the largest thickness in the headline. A 240-volt plasma cutter rated for at least 5/8-inch cutting is a sensible starting category for frequent half-inch work.
Dual-voltage cutters make sense when portability is useful or the shop has both 120- and 240-volt outlets. Treat 120-volt operation as a convenience for thinner material and light work, not a substitute for full-capacity cutting. A dual-voltage plasma cutter can be a good compromise if you accept that its strongest performance depends on 240 volts.
Air-plasma cutters require a clean, dry air supply at the pressure and flow the machine specifies. A small compressor that cannot maintain the required flow can cause a ragged cut, sputtering, or frequent pauses. Factor in a water separator or suitable air treatment if your shop air carries moisture or oil. Built-in compressors avoid a separate air line but add weight and limit available airflow; check the machine’s capacity before assuming it will handle repeated half-inch cuts.
How the main options compare
| Option | Best fit | Main trade-off |
|---|---|---|
| 240 V inverter, 5/8-inch-plus rated capacity | Frequent half-inch plate work | Needs suitable 240 V power and compressed air |
| Dual-voltage inverter | Mixed shop and field use | Less capacity on 120 V; full output still needs 240 V |
| Lower-cost, lower-capacity cutter | Occasional cuts and thinner stock | Slow or rough cuts near its limit; less production headroom |
| CNC-ready cutter | Table cutting and repeatable profiles | May require compatible controls, torch, and consumables |
Torch, consumables, and shop use
Consumables are not an afterthought. Electrodes, nozzles, swirl rings, and shields wear, and the wrong parts can produce an unstable arc or poor cut quality. Check that replacement consumables are readily available and that the torch is comfortable for the type of work you do. A pilot arc can help when starting on painted, rusty, or expanded metal, but it does not eliminate the need to prepare the cut path or maintain consumables.
For repeated straight cuts, a machine that accepts a guide or mechanized torch setup can save time. For occasional brackets and repairs, paying extra for CNC features is unnecessary. If you plan to connect a cutter to a table, verify the interface and torch compatibility before purchase; “CNC-ready” can mean different things across products.
Getting a clean cut through half-inch plate
Remove heavy rust, paint, oil, and scale where the work clamp will attach. Poor electrical contact can interrupt the arc, while coatings can contaminate the cut and produce fumes. Set air pressure and output according to the manual, keep the torch square to the plate, and travel at a steady speed. Moving too slowly leaves a wide kerf and excess dross; moving too fast can leave an incomplete cut or a pronounced bevel. Watch the arc: a clean cut sends sparks through the bottom of the plate, rather than letting them trail backward along the top.
Thick plate needs sound workholding and a safe path for sparks and molten metal. Wear appropriate eye, hand, and body protection, and provide ventilation—especially when cutting coated or unknown material. Plasma cutting can also create substantial noise and ultraviolet light, so protect people nearby, not only the operator.
When the cheaper cutter is enough
If half-inch steel means a few short cuts a month, a less expensive machine may be a reasonable choice. It can still do the job if its rated capacity, power supply, and duty cycle match your actual work. Budget for air treatment and consumables rather than spending every dollar on advertised amperage. If half-inch plate is a daily material, or cut edges need little cleanup, choose more capacity than the minimum and compare real rated-cut specifications. The extra margin buys faster work and fewer frustrating cuts at the machine’s limit.