-4- © COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON IX





Lesson 1
The Basics of Arc Welding
Lesson 2
Common Electric
Arc Welding Processes
Lesson 3
Covered Electrodes for Welding
Mild Steels
Lesson 4
Covered Electrodes for Welding Low Alloy Steels
Lesson 5
Welding Filler Metals for Stainless Steels
Lesson 6
Carbon & Low Alloy
Steel Filler Metals -
GMAW,GTAW,SAW
Lesson 7
Flux Cored Arc Electrodes Carbon Low Alloy Steels
Lesson 8
Hardsurfacing Electrodes
Lesson 9
Estimating & Comparing Weld Metal Costs
Lesson 10
Reliability of Welding Filler Metals
9.2.4 Deposition Efficiency - Deposition efficiency is the relationship of the weight of the weld metal deposited to the weight of the electrode (or wire) consumed in making a weld. It can be accurately determined only by making a timed test weld, and carefully weighing the weldment and the electrode or wire, before and after welding.  The efficiency can then be calculated by the formula: Deposition efficiency    = Weight of Weld Metal  ÷  Weight of Electrode Used (or) Deposition Rate (lbs/hr)  ÷  Burn-off Rate (lbs/hr) 9.2.4.1 The deposition efficiency tells us how many pounds of weld metal can be expected from a given weight of the electrode or welding wire purchased.  As an example, 100 pounds of a flux cored electrode with an efficiency of 85%, will produce approximately 85 pounds of weld metal, while 100 pounds of coated electrode with an efficiency of 65%, will produce approximately 65 pounds of weld metal, less the weight of the stubs discarded, as described below. 9.2.5 Coated Electrodes - The deposition efficiency of coated electrodes by AWS definition, and in published data, does not consider the loss of the unused electrode stub that is discarded.  This is understandable since the stub length can vary with the operator and the application.  Long continuous welds are usually conducive to short stubs while on short inter- mittent welds, stub length tends to be longer.  Figure 3 illustrates how the stub loss influences the electrode efficiency when using coated electrodes. 9.2.5.1 In Figure 3, a 14” long by 5/32” diameter E7018 electrode at 140 amperes is con- sidered.  It is 75% efficient, and a two inch stub loss is assumed.  The 75% efficiency applies FIGURE 3 DEPOSITION EFFICIENCY = 75% actual efficiency, including stub loss = 9 ÷ 14 = 64.3% 12" LENGTH OF ELECTRODE CONSUMED AMOUNT THAT BECOMES WELD METAL (LENGTH CONSUMED X EFFICIENCY) 14" LOST TO SLAG,SPATTER & FUMES 2" STUB LENGTH 9"
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