Explain how to measure the wirefeed ipm The working rangeSol

Explain how to measure the wire-feed ipm. The working range.

Solution

Most welding professionals know the wire-feed speed (WFS) where a process runs well based on their experience, or can quickly get WFS from manufacturer\'s recommended procedures. However, determining how fast to travel for a particular size weld bead ends up being an iterative, time-consuming process. By understanding a few concepts and doing some math with a few simple formulas, we can determine at least a good starting point for a welding procedure that produces the desired weld.

Deposition rate — It is essential to recall that Deposition Rate is directly proportional to the speed at which a particular wire diameter emerges from a welding gun during welding. Deposition rate has nothing to do with how fast the gun is traveling nor the voltage setting on the machine. Deposition rate is simply a measure of how many pounds of wire come from the welding gun in a certain amount of time, typically measured in lb./hr. If wire-feed speed increases, deposition rate increases. We also understand that if we maintain the wire-feed speed and change to a larger diameter wire, deposition rate will increase as well. Armed with this understanding, calculating deposition rate ends up being a very powerful exercise that gives you a number that can be used to calculate key welding parameters.

Let\'s look at the formula and an example:

Deposition rate calculation

Deposition rate (lb./hr) = 13.1×(Wire diameter)²×(Wire-feed speed)×(Efficiency)

E.g.: Wire diameter = 0.045 in. (1.2 mm) solid wire, WFS = 300 IPM.

Deposition rate = 13.1×(0.045)² ×(300)×(1.0) = 7.96 lb./hr

Calculating travel speed with deposition rate — Knowing the deposition rate, we can calculate the travel speed in inches per minute (IPM) for a particular weld. Let\'s say we want to make a 3/8-in. steel fillet weld (assume 10% reinforcement or 0.4125 in. leg) using 0.045-in. solid wire at 300 IPM, the weight of weld metal per foot can be calculated by multiplying the density of steel (0.283 lb./in³) by the volume of weld metal per foot as follows:

Weld weight per foot calculation

Vol. of weld metal/ft=1/2×b×h×12 in.=1/2×0.4125 in.×0.4125 in.×12 in.=1.02 in³.

Weight of weld metal/ft of 3/8 in. fillet weld=(0.283 lb./in³)×(1.02 in³)=0.2887 lb./ft.

From the calculation below, we see that the travel speed for a one-pass, 3/8-in. fillet weld would be 5.52 IPM, 11.03 IPM for a two-pass fillet weld, or 16.55 IPM for a three-pass weld.

Travel speed calculation

Travel speed = (deposition rate)×(# of passes)/5×(weight of weld metal per foot {lb./ft}) = (7.96)×(1)/5 × (0.2887) = 5.52 IPM

Calculating wire-feed speed with deposition rate — Let\'s assume a requirement to make fillet welds at a rate of 12 lb./hr using 0.045 in. welding wire. We can calculate the WFS using the formulas below and Weight of Weld Wire per foot in Table 1.

Wire-feed speed calculation

Wire-feed Speed = (deposition rate)/5×(weight of wire per foot {lb./ft}) = (12)/5×(0.0054) = 444.4 IPM

Of course, the travel speed for a one-pass, 3/8 in. fillet weld at 12 lb./hr deposition rate would be 8.31 IPM as calculated below.

Travel Speed = (deposition rate)×(# of passes)/5×(weight of weld metal {lb./ft}) = (12)×(1)/5×(0.2887) = 8.31 IPM

Making it easier — The Bartonian Conversion Factor (Table 2) makes things a bit easier for fillet welds. The example below uses the conversion factor to calculate travel speed at 5.57 IPM for that same 3/8 in. fillet weld using a 0.045 in. solid wire.

Travel Speed = 7.96×0.7 = 5.57 IPM (.2887)

Table 1: Weight of Wire

Wire Diam., in.	Weight of Wire (lb./ft)	Wire Diam., in.	Weight of Wire (lb./ft)
0.035	0.0033	3/32	0.023
0.040	0.0043	1/8	0.042
0.045	0.0054	5/32	0.065
0.052	0.0072	3/16	0.094
1/16	0.01	7/32	0.128
5/64	0.016