A common question that is asked when manufacturers are trying to determine costs associated with welding is: How many pounds of wire can I deposit per hour? Or, how many pounds of wire can I deposit at a specific amperage or wire feed speed?   There are charts to help you determine this, but it’s always good to have a simple formula.

Before we get into this calculation is very important to make a distinction between deposition rate and melt-off rate.  A lot of people in our industry use these two terms interchangeably and that is not correct.  Melt-off rate is how much wire is being consumed and does not take into account the efficiency of the electrode.  Deposition rate is how much wire is actually converted into weld metal.  Solid wire efficiencies can range from 88 – 98%, so you can have the exact same melt-off rate but considerably different deposition rates if you are welding at the same wire feed speed but with a different mode of metal transfer.

So now to the formula:

Deposition Rate =  13.1 (D²) (WFS)(EE)

D = electrode diameter

WFS = wire feed speed (in/min)

EE = electrode efficiency

13.1 is a constant used for steel and it is based on steels density. This same constant can be used for stainless steel wires as it is only 1/1000 difference.  Aluminum on the other hand would have to be a constant of about a third that of steel, or 4.32.

Electrode efficiencies for solid wires can vary depending on the mode of metal transfer.  We are not going to get into the specifics of how to achieve each at this time.  Below are typical efficiencies for each of the modes.

Short-circuit Transfer: 90-93%

Surface Tension Transfer:   98%  (STT is a trademark and of the Lincoln Electric Company)

Globular Transfer: 88 – 90%

Axial Spray Transfer: 98%

Pulsed Spray Transfer: 98% is typical, but can be lower depending on the parameters and power source

Example: A customer wants to know the deposition rate of an .052 ER70S-6 wire.  They are running 90/10 shielding gas at 320 in/min and 30 volts.  We are in spray transfer mode at these settings.

Deposition Rate = 13.1(0.052)² (320) (0.98) = 11.1 pounds per hour

NOTE: This formula only works for with imperial units, if you are using the metric system simply follow the following steps:

1. Calculate the area of the circle ->  Radius squared * pi
2. Multiply times the density of the metal being used
3. Multiply times the wire feed speed
4. Multiply times 60 (to get deposition rate per hour if wire feed speed was expressed per minute)
5. Adjust any units to match (i.e if you used cm for the density or other units)
6. Multiply by the efficiency of the electrode

Source: Lincoln Electric’s GMAW Welding Guide