©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
III 3.4.2
Electrode
Deposition -
The deposition rate
of a given electrode influences the
total cost of depositing weld metal
substantially. The deposition rate is the weight of weld
metal deposited in a unit of time.
Deposition rate increases as the welding current increases
within the limits of a given electrode.
As can be seen in Figure 4, a 5/32" diameter E7024
electrode can deposit weld metal more
than twice as fast as a 5/32" diameter E6010 elec- trode.
It is apparent that a substantial saving in labor and overhead can be achieved
if one of the
higher deposition electrodes can be used. 3.4.2.1
The deposition
efficiency of a given electrode also has an effect
on welding costs. The
deposition efficiency is the weight of the weld metal deposited compared to the
weight of the
electrode consumed, expressed as a percentage. Average
Class Efficiency*
E6010 63.8%
E6011 68.5%
E6012 66.9%
E6013 66.8%
E7014 64.6%
E7016 62.8%
E7018 69.5%
E6020 65.2%
E7024 66.8%
E7027 68.6%
* Includes 2" Stub Loss
Stub Loss ** Stub
5/32" 6010 %
Loss Length
% Deposit 14"
Electrode 2"
63.8% 36.2%
3" 58.5%
41.5% 4"
53.2% 46.8%
5" 47.9%
52.1% 6"
42.6% 57.4%
** E6010 is 71.57% efficient.
Loss due to slag, spatter, and smoke
EFFICIENCY =
Weight of Weld Metal
Weight of Electrode Used
ELECTRODE EFFICIENCY AND STUB LOSS
FIGURE 5 3.4.2.2
When welding with coated electrodes,
some of the electrode weight is lost as slag, spatter,
fumes, gases, and stubs. If an electrode is 65% efficient, it means that
for every 100 pounds
of electrodes consumed, 65 pounds of weld metal will be produced. Stub loss,
the part of the
electrode that is thrown away, is not considered in the deposition efficiency,
since the stub
length will vary with the operator or the application. Figure 5 illustrates
how stub loss affects
efficiency. An 6010 electrode has an actual average efficiency of 71.5%
before the allowance
for stub loss. A 2" stub results in the efficiency dropping to 63.8%. If
6" stubs are thrown
away, 100 pounds of electrodes will produce only 42.6 pounds of weld metal. Methods
of calculating total weld costs will
be covered in a subsequent lesson.
