Weld Deposition Rate

A wire of known diameter fed at a known speed delivers a known volume of metal per minute; multiply by density for the mass, and by the deposition efficiency for the fraction that stays in the joint rather than leaving as spatter, slag or fume. This is the equation that turns a welding procedure into an estimate, and it is the one that decides whether a fabrication is quoted profitably.

Watch the square on the diameter. It is the reason a small step in wire size is a large step in output. Moving from 1.0 mm wire to 1.2 mm at the same feed speed gives 44 % more metal, not 20 %. Moving to 1.6 mm gives two and a half times as much. It runs the other way with equal force when somebody loads the wrong spool and nobody notices because the arc still sounds right.

Deposition efficiency is not melting efficiency, and the difference is where the estimating money hides. Everything fed off the spool melts — the question is how much of it ends up in the joint. Solid wire under gas runs high, with spray transfer losing very little and short-circuit transfer losing more to spatter. Flux-cored and metal-cored wires carry flux that becomes slag, so the deposit is a good deal less than the wire consumed even though every gram of wire was used as intended. Stick electrodes lose the coating and the stub, which is why their efficiency is the lowest of the lot and why stub-length discipline shows up directly in the consumable bill. Get the figure from the consumable manufacturer's own data for the wire and the transfer mode you are actually running, or measure it: weigh a test plate, run a timed weld at a known feed speed, weigh it again.

And this is an arc-on rate, not shop output. The number this page returns assumes the arc is burning continuously. Multiply by an operating factor — the fraction of the shift the arc is actually lit — before anyone quotes from it. Hand-held semi-automatic work spends most of the day not welding: positioning, tacking, changing position, chipping slag, cleaning, waiting for a crane. Operating factors for manual work are low enough to be startling the first time somebody measures them, and the gap between arc-on rate and shop output is where mechanisation and positioners earn their keep. A robot's advantage over a good welder is far less about deposition rate than about operating factor.

Two smaller notes. The feeder's dial may read inches per minute or metres per minute, and this page's picker offers metres per minute and feet per minute because those are the units the engine has — 400 in/min is 33.3 ft/min, and dividing or multiplying by twelve at the wrong moment is a real error with no symptom other than a weld that comes out wrong. And a cored wire is the awkward case for density: its cross-section is not solid metal, so the bulk figure that belongs in this equation is lower than the density of the metal itself, and the manufacturer's kilograms-per-metre data beats any calculation from the outside diameter.