©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
IX 9.2.6
Efficiency
of Flux Cored Wires - Flux cored wires have a lower flux-to-metal
ratio than
coated electrodes, and thereby, a higher deposition efficiency. Stub loss
need not be considered
since the wire is continuous. The gas shielded wires of the E70T-1 and E70T-2
types have efficiencies of 83%-88%.
The gas shielded basic slag type (E70T-5) is 85%-90%
efficient with CO2 as the shielding
gas, and the efficiency can reach 92% when a 75% argon, 25%
CO2 gas mixture is used. Use the efficiency figures in Figure 9 for your
calculations if the actual
values are not known. 9.2.6.1
The efficiency of the self-shielded
types of flux cored wires has more variation because
of the large variety of available types that have been designed for specific applica-
tions. The high deposition general
purpose type, such as E70T-4, is 81%-86%, depending on wire
size and electrical stick-out. The chart in Figure 9 shows the optimum conditions
for each wire
size and may be used in your calculations. 9.2.7
Efficiency
of Solid Wires for GMAW - The efficiency of solid wires
in GMAW is very
high and will vary with the shielding gas or gas mixture used. Using CO2
will produce the most
spatter and the average efficiency will be about 93%. Using a 75% argon-25%
CO2 gas mixture
will result in somewhat less spatter, and an efficiency of approximately 96% can
be expected. A
98% argon-2% oxygen mixture will produce even less spatter, and the average
efficiency will be about 98%. Stub
loss need not be considered since the wire is continuous.
Figure 6 shows the average efficiencies
you may use in your calculations if the actual effi- ciency
is not known. FIGURE
5 ELEC.
DEPOSITION 2"
3" 4"
5" LENGTH
EFFICIENCY STUB
STUB STUB
STUB 60%
50.0% 45.0%
40.0% 35.0%
65% 54.2%
48.7% 43.3%
37.9% 12"
70% 58.3%
52.5% 46.6%
40.8% 75%
62.5% 56.2%
50.0% 43.7%
80% 66.6%
60.0% 53.3%
46.6% 60%
51.4% 47.1%
42.8% 38.5%
65% 55.7%
51.1% 46.4%
41.8% 14"
70% 60.0%
55.0% 50.0%
45.0% 75%
64.3% 58.9%
53.6% 48.2%
80% 68.5%
62.8% 57.1%
51.4% 60%
53.3% 50.0%
46.6% 43.3%
65% 57.7%
54.2% 50.5%
46.9% 18"
70% 62.2%
58.3% 54.4%
50.5% 75%
66.6% 62.5%
58.3% 54.2%
80% 71.1%
66.6% 62.2%
57.7% STUB LOSS
CORRECTION TABLE FOR COATED
ELECTRODES EFFICIENCY
INCLUDING STUB LOSS
