Assessments - 3, GPA: 4.7
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Electrodes used for shielded metal arc welding have two parts. The inner core is a metal rod or wire that should be similar in composition to the base metal. The outer coating is called flux. Various types of flux exist. Each coating is used for a particular welding situation. While the metal is molten, it can be contaminated by elements in the air. This contamination could weaken the weld. The flux coating creates a protective barrier called slag that protects the molten metal from contaminants. When current (amperage) flows through the circuit to the electrode, an arc is formed between the end of the electrode and the work piece. The arc melts the electrode and the work piece. The melted metal of the electrode flows into the molten crater and forms a bond with the work piece as shown in Figure 5. figure 5 Weld Slag Crater Work Piece Flux Wire NOtE: Discontinue using and discard electrodes that burn down to 1 to 2 inches from the electrode holder. STRIkInG An ARC Place the bare end of the electrode in the holder. Grip the holder lightly to reduce tiring of the hand and arm. NOtE: Always keep the jaws of the holder clean to insure good electrical contact with the electrode. Be careful not to touch the work piece or welding bench with the electrode as this causes arc flashes. There are two methods which can be used to start or strike the arc; the tapping method and the scratching method. In the tapping method, the electrode is brought straight down and tapped on the work piece. With the scratching method, drag the electrode at an angle along the surface much like striking a match. Regardless of method, upon contact with the plate, immediately raise the electrode a distance equal to the diameter of the electrode or it will stick to the surface. Always hold the electrode pointed into the weld (See Figure 6). figure 6 Same as electrode diameter Same as electrode diameter NOtE: Should the electrode stick to the work piece, break it loose by quickly twisting or bending at the holder while pulling upward. If the electrode does not break loose, disengage the electrode by releasing it from the holder. WS4369 and WS4469 ARC WelDInG BASICS Five basic techniques affect weld quality. These are: electrode selection, current setting, weld angle, arc length, and travel speed. Proper implementation of these techniques is necessary for good weld quality. eleCTRODe TyPe AnD SIze The correct choice of electrode type involves a variety of factors, such as welding position, work piece material type, thickness, and condition of surface to be welded. The American Welding Society, AWS, has set up certain requirements for each type of electrode. All electrodes are classified into five main groups: mild steel, high-carbon steel, special alloy steel, cast iron, and nonferrous such as aluminum. The majority of arc welding is done with the electrodes in the mild steel group. The electrode material should corres-pond with the work piece material. Flux coatings are made for use with either AC (alternating current), DC (direct current) reverse polarity, or DC straight polarity, although some function well on both AC and DC current. AWS eleCTRODe ClASSIfICATIOn E-6 0 1 3 E = Electrode 60 = Mild steel 70 = High strength Steel 1 = Electrode can be used in all positions 2 = Electrode is restricted for use in flat or horizontal position only Flux type Operating Instructions and Parts Manual WS4369 and WS4469 Welding Guidelines Consult specifications listed on the welders should weld from right to left. (Continued) electrode package or generalized chart The electrode should always point into in the Operation section. Excessive the weld puddle as shown. COMMOnly USeD eleCTRODeS current burns through light metals, ARC lenGTh 1. e-6011 Deep Penetrating • The strong arc force and rapid solidification of the metal makes vertical and overhead welding easier with this rod. • Where time does not permit rust, scale or paint removal, this rod penetrates rapidly and easily. • Acceptable for AC or DC welding current (reverse polarity). 2. e-6013 General Purpose • All position, smooth deposit rod with low spatter. • For all mild steel and general purpose work. • Acceptable for AC or DC welding current (straight or reverse polarity). 3. e-7014 Iron Powder • A general purpose "drag" rod for all positions. • Ideal for situations where fit between metal pieces is poor. • The iron powder in the flux coating combines with the filler rod to make a smooth deposit with very little spatter. • Ideal for ornamental work. • Acceptable for AC or DC welding current (reverse polarity). 4. e-7018 low hydrogen • An all position high strength electrode designed to produce low hydrogen content combined with excellent mechanical properties. • Acceptable for AC or DC welding current (reverse polarity). CURRenT The correct current involves the adjustment of the welding machine to the required amperage setting. Current represents the actual flow of electricity and i...
Este manual também é adequado para os modelos :Máquinas de soldar - IN973900AV (3.74 mb)
Máquinas de soldar - WS4469 (3.74 mb)