Plasma Cut Time, Consumable Life, and Cost per Part

The electrode and nozzle wear two ways and are rated two ways: each pierce blasts the electrode's hafnium insert, so a set carries a rated number of pierces, and steady cutting erodes it more slowly, so a set also carries a rated number of arc-on hours. Which limit arrives first depends entirely on the part -- a sheet full of small holes burns pierces, and a long straight rip burns hours -- so reporting both and naming the one that governs is what makes the calculation useful for quoting. A shop that costs consumables per pierce will underprice long cuts, and a shop that costs them per hour will underprice hole-intensive ones, and on a production run the difference is real money. A part with 240 in of cut at 40 in/min and 4 pierces takes 6 minutes of arc, which is a tenth of an hour, so a $35 set rated 500 pierces or 3 arc hours gives 125 parts on pierces but only 30 on hours: arc hours govern by a factor of four and the consumable cost is $1.17 a part, not the $0.28 a pierce-based estimate would have said. Reverse the part into a nest of 60 small holes with 30 in of cut and pierces govern instead, at 8 parts per set and $4.38 apiece -- same machine, same material, an order of magnitude apart. A costing estimate; the torch manufacturer's published consumable ratings and cut charts, and the shop's own consumable logs, govern.

cut_time_min = cut_length_in / cut_speed_ipm; arc_hours_per_part = cut_time_min / 60; parts_by_pierces = floor(rated_pierces / pierces_per_part); parts_by_arc_hours = floor(rated_arc_hours / arc_hours_per_part); parts_per_set = the smaller; cost_per_part = set_cost / parts_per_set.

Plasma consumable life from the two ratings a set carries -- pierces and arc-on hours -- with the smaller of the two governing, by name; the ratings and the cut speed for the amperage and thickness come from the torch manufacturer's published cut charts, entered rather than bundled. The manufacturer's ratings and the shop's own consumable logs govern.

The life and cost arithmetic is division on the shop's own part geometry and the manufacturer's published ratings, which the user enters.

Estimate. AHJ and licensed professional govern.

Field names used by the API: cut_length_in, cut_speed_ipm, pierces_per_part, set_cost, rated_pierces, rated_arc_hours, cut_time_min, arc_hours_per_part, parts_by_pierces, parts_by_arc_hours, cost_per_part

• Two ratings a set is rated in pierces AND in arc-on hours; the smaller number of parts governstorch manufacturer consumable ratings
• Whole parts parts per set are floored; the set is exhausted when either limit is reachedshop practice
• Cut speed from the manufacturer's cut chart for the amperage and thickness in use, entered rather than bundledtorch manufacturer cut charts