Plasma cutter duty cycle: what the percentage means

You are halfway along a 3 mm bracket, the inverter case is already warm, and the listing you ordered from showed either 35% or 60%. A plasma cutter duty cycle answers that only when two numbers travel together: a percentage, and the current it belongs to. The percentage is the share of a ten-minute period the power source may spend cutting at that stated current. In the eleven amazon.co.uk listings in our plasma cutter comparison, only the Reboot CUT60 attaches 35% to its 60 A description. The SUSEMSE LT55 prints "60% high-duty circle" and names no amps. The other nine pages print nothing, and nothing is not a licence to cut all afternoon.

In short

A plasma cutter duty cycle is a fraction of ten minutes at a named current. Thirty-five percent is three and a half minutes of cutting in that window, and only at the current printed beside it. Sixty percent is six minutes, and only when the listing actually states the current. Where this set prints neither number together, treat the duty cycle as n/a and plan short cuts with a cool-down, rather than a continuous run at the headline amp.

What a plasma cutter duty cycle is counting

The useful reading is a clock, not a quality score. Take the ten minutes as the whole window. At 35%, the arc-on allowance is three and a half minutes, and the rest of the ten minutes is there for the power source to cool. At 60%, the arc-on allowance is six minutes. That arithmetic follows from the definition. It is not a stopwatch test of any machine in this set, and it collapses the moment the current is missing.

The current is the part people skip. A 35% rating at 30 A and a 35% rating at 60 A are different thermal jobs, because the inverter is shedding different amounts of heat. A 60% line with no amps beside it does not tell you whether those six minutes were claimed at 20 A, at 40 A, or at the biggest number in the title. You can still buy the cutter. You cannot turn the percentage into a working timetable.

The two figures these listings print

Eleven inverter air plasma cutters sit in the comparison file, from Reboot, SPRIGHOLLY, PLASMARGON, Haxiaoer and SUSEMSE, with shelf prices from £67.83 to £199.00 on amazon.co.uk. They are not Stahlwerk machines. Duty cycle is printed on two of the eleven pages.

The Reboot CUT60, ASIN B0DTG34CST, is the clear one. The listing price in this file is £132.04, with 4.6 from 28 reviews. A bullet puts a 12 mm clean cut, a 16 mm maximum and a 35% duty cycle on the 60 A description. Technical details say 240 V. The page does not print a plug rating. If you take the bullet as written, 35% at that 60 A description is three and a half minutes of arc in each ten-minute window, at that current.

The SUSEMSE LT55, ASIN B0C61S56PB, is the unclear one. The listing price is £99.99, with 4.1 from 34 reviews. The title says 55 A. A bullet says "60% high-duty circle". No current is attached to that percentage. Planning six minutes at 55 A from that phrase would invent the missing half of the spec.

The other nine pages leave the duty-cycle line empty: the SPRIGHOLLY CUT50L, CUT60 and CUT60L PRO, the Reboot 45 A, the Reboot non-HF 40 A, the PLASMARGON CUT55, PLC65 and CUT65 Pro, and the Haxiaoer HXC600D. The CUT50L, ASIN B0GKDNVWPD, at £67.83, does not print one. The missing percentage is still a missing percentage, on the cheap machine and on the £199 non-HF machine alike.

A review that says 60 percent

One UK review of the Reboot CUT60 states a 60% duty cycle. Keep that sentence in the review column. The bullet on the same product says 35%, attached to the 60 A description. Averaging them to something near 47% would describe no document you can point at. Use 35% at the 60 A description as the listing claim. When the machine arrives, the label and the manual outrank both.

Why a 13 amp machine prints a lower current

A BS 1363 plug with a 13 A fuse is rated at 13 A. That is the input side, at the wall. The 40 A, 50 A, 55 A and 60 A numbers on these titles are output claims at the torch. They are not the current the fuse is carrying. These listings do not print the input current next to the duty cycle, so you cannot finish the sum from the product page alone.

R-Tech's P32D shows what a complete line looks like on a different machine. That page publishes 35% at 30 A, a lower output so the input can stay at 13 A, with an 8 mm clean cut and 12 mm severance. Those are R-Tech's figures for R-Tech's cutter. Copying "35% at 30 A" onto the Reboot, the SUSEMSE, or the SPRIGHOLLY CUT50L would invent a spec their amazon.co.uk pages do not carry.

A long SPRIGHOLLY review, in the research behind this comparison, says these inverters are often happy near half the headline current on a 13 A plug, and that full headline current needs a higher-rated supply. Treat that as the reviewer's rule of thumb, not as a British Standard and not as a result we measured. Half of a 60 A title is 30 A. One verified review of the Reboot CUT60 says a 13 A fuse blew. Plugs and fuses are covered in the guide to a plasma cutter on a 13 amp supply. Anything beyond a standard 13 A socket is an electrician's job.

What to do when the cutter stops

Stop the arc and leave any thermal cut-out exactly as the maker fitted it. Bridging a sensor or holding the trigger through a trip turns a pause into a burnt inverter or a damaged torch. Unplug the machine and give it the remainder of that ten-minute window at least. Waiting six minutes and striking again at the same headline amp, on the same long extension, repeats the condition that stopped you.

Every cutter in this set needs an outside compressor, and no box includes one. The CUT50L bullet asks for 90 PSI and 60 L/min. The Reboot CUT60 lists 30–70 psi. The SUSEMSE lists 0.35–0.5 MPa, which the page also gives as 50–70 psi. A dry or starving torch can stop a cut and can overheat a tip. It is a different diagnosis from "the percentage was too low".

After a cool case and a restored air supply, a cutter that strikes again was behaving like a limited duty cycle or a supply limit. A cutter that will not hold an arc, or that fails again after a short spell of normal use, is a fault. The Consumer Rights Act 2015 gives you 30 days to reject goods that are faulty. Leave the fuse at the rating the plug and the circuit were built for.

How to read the next listing

Read the duty line as a pair before you compare prices. First, is there a percentage at all? Second, is a current in the same claim? A page that passes only the first test, as the SUSEMSE does, is unfinished. A page that passes both, as the Reboot CUT60 bullet does, can be turned into minutes with the ten-minute sum. A page that fails the first test gets n/a written next to it. Nine of these eleven fail that test.

The Reboot's 35% does not transfer to the CUT50L. The SUSEMSE's 60% does not transfer to a PLASMARGON title. R-Tech's 35% at 30 A does not transfer to any of these ASINs. Silence is allowed. Filling silence with a neighbour's number is how a buying note becomes a false spec.

Prices and review counts above are the amazon.co.uk shelf figures stored for this comparison in October 2026. Products Compared read the eleven listings, including bullets, technical details and the review lines those files contain, and used R-Tech's published 35% at 30 A on the P32D as a separate UK example. We did not cut metal in a lab, and we did not invent duty cycles for the nine pages that omit one. Links to amazon.co.uk use the tag pcuk26-21. A qualifying purchase can earn a commission at no extra cost to you.