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Rick V
01-12-2007, 02:53 PM
How Many Feet of MIG Wire on a Spool?

Once in a while I need the answer, so here it is.
I provide one sample calculation (that you can ignore) followed by a Table for the common MIG wire sizes in steel, stainless steel (SS), aluminum and for reference - copper.

Material Density------gm/cm^3----lbs/in^3
Iron/Steel------------7.7--------0.27812
Stainless Steel ------8.0--------0.28896
Aluminum--------------2.7--------0.09752
Copper----------------8.9 -------0.32147

Sample Calculation
How many feet of 0.035 inch diameter mild steel wire in a 2 lb spool of MIG wire?
Density conversion factor: 1 gm/cubic cm = 0.03612 lbs/cubic inch
Density of steel = 7.7 gm/cubic cm or 7.7 x 0.03612 = 0.27812 lbs/cubic inch
2 lbs of steel wire has a volume of 2 lbs / 0.27812 lbs/cubic inch = 7.191 cubic inches.
Wire of 0.035 inch diameter (D) has a cross-sectional area of = pi/4 x DxD = 3.14156/4 x 0.035 x 0.035 = 0.000962113 square inches.
Wire Volume = Wire Length x Wire Area.
Wire Length = Volume/Area = 7.191 / 0.0009621 = 7,474.3 inches or 622.8 feet.

Formula: Wire Length = [weight of wire (lbs) / density (lbs/in^3)] / [3.14159/4 x Diam^2 (inches^2)]

TABLE: FEET OF MIG WIRE ON A SPOOL (Solid Wire, not Flux Core)

Wire Diam---Spool--Steel----SS------Aluminum---Copper
(inches)---(lbs)---(feet)--(feet)---(feet)-----(feet)
0.023--------1-------721------694-----2056-------624
0.023--------2------1442-----1388-----4112------1248
0.023--------10-----7210-----6940----20560------6240
0.023--------44----31724----30536----90464-----27456

0.030--------1-------424------408-----1209-------367
0.030--------2-------848------816-----2418-------734
0.030--------10-----4240-----4080----12090------3670
0.030--------44----18656----17952----53196-----16148

0.035--------1-------311.4----300------888-------269.4
0.035--------2-------623------600-----1776-------539
0.035--------10-----3114-----3000-----8881------2694
0.035--------44----13703----13189----39080-----11855

0.045--------1-------188.4----181------537-------163
0.045--------2-------377------362-----1074-------326
0.045--------10-----1884-----1810-----5373------1630
0.045--------44-----8289-----7978----23640------7172

0.060--------1-------106------102------302--------91.7
0.060--------2-------212------204------604-------183
0.060--------10-----1060-----1020-----3022-------917
0.060--------44-----4662-----4488----13298------4034

Rick V

pulser
01-12-2007, 06:46 PM
Good info Rick.
Based on wire feed rate and arc time, or on weld joint volume, you can figure how much wire you're using in lbs or feet.

Rick V
01-13-2007, 03:29 PM
Hey Pulser, your are right... and once in a while folks tell us tales of how many lbs per hour they were laying down.

Not only that, the Table is interesting/useful if a fellow takes the time to measure (calibrate) the wire-speed at various settings of his welding machine.
e.g.
Here is the Wire Feed Measurements from my Lincoln Mig PAK 15 (SP-175T)
Setting inches/min
Min. 48
1. 51
2. 90
3. 140
4. 190
5. 265
6. 320
7. 380
8. 440
9. 500
10.. 560
Max... 563

Question: If my welder was loaded with a new 2 lb spool of 0.023 inch diameter steel MIG wire, I could weld continously at setting #4 for how long?

According to the Table, 2 lbs of 0.023 = 1442 feet or 12 x 1442 = 17304 inches.
Setting #4 = 190 inches/minute
Therefore, number of minutes = 17304 / 190 = 91 minutes or about 1.5 hours.

How much gas would I use? If I were running a typical gas flow of 15 cubic feet per hour, I would use/need 1.5 hours x 15 ft^3/hour = 22.5 cubic feet.

The range of my welder settings, maximum speed to minimum gives me from 1/2 hour to 6 hours continuous welding from a 2 lb spool of 0.023 solid wire.

Rick V