Assessments - 1, GPA: 5 ( )

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As a general rule calculate 40 amps welding current per 1 mm of electrode core wire diameter. Depending on electrode type, material thickness and weld position this calculated value may have to be adjusted plus or minus. The Invert 130/40 and 130/60 works perfectly with thin plate, which is the outstanding feature of this machine, aside from its extreme compact and robust design. It is characteristic of an inverter to generate a true direct current, which makes for a soft and smooth running arc with reduced spatter formation. Overview Of Stick Electrodes And Their Correct Use In order to achieve a good weld the electrode has to be dry, so storing in a dry place is essential. Should electrodes have become moist, dry in an oven at 200°C to 300°C for 1 - 2 hours. Basic-coated electrodes always require pre-drying at 200°C to 300°C for 3 hours, unless they are vacuum-packed. Stick electrodes are coded according to EN 499 and other standards, such as B.S. 639, AWS-SFA 5.1 and ISO 2560. The codes are always shown on the electrode package. The electrode description is defined by the manufacturer according to the standards, the description is checked by an independent test institute for compliance. This information is shown on the packaging. Welding Hints Because of the multitude of and great differences in the important points for welding only the very basic operations for the most common electrodes for low-carbon steels, the rutile or rutile cellulose electrode, are introduced here. In the case that other electrodes have to be used, the electrode manufacturers supply upon request all relevant information for the type of special electrode to be used. Always make some trial welds on scrap material. Select electrode diameter and welding current as per Table 1. Attach earth clamp to work piece and place electrode into electrode holder as described earlier. Now hold the electrode tip approx. 2 cm above the starting point of your weld seam. Hold the welding visor in front of your face and draw the electrode with a short stroke along the groove. Through the welding shield you watch the arc, keeping it to a length of 1 to 1.5 times the electrode diameter. wrong arc too long (Figure 3) correct approx. 1 - 1.5 the electrode-O (Figure 4) The correct arc length is important for a good weld, because with too short or too long an arc both welding current and working voltage change. A low working voltage causes insufficient penetration. Too high or too low welding current gives a poor welding seam. Too long an arc does not sufficiently melt the parent material, resulting in high spatter losses. Also the air, with its detrimental substances like hydrogen and nitrogen, may get access to the weld pool. For a good weld the work angle of the electrode (or electrode inclination angle) is of substantial importance. The inclination should be 70° - 80° to the welding direction. With the work angle too steep slag will run under the weld pool, too flat an work angle causes the arc to spatter, in both cases the result is a porous, weak welding seam (see figure 5 - 7). < 70° welding direction > 80° welding direction 70-80° welding direction wrong wrong correct (Figure 5) (Figure 6) (Figure 7) The welder has to keep the arc at the same length, that is the electrode burn-off is compensated by feeding the electrode into the weld. At the same time the welder has to watch the weld pool for even penetration and width. Welding is always done from left to right (backhand welding). At the end of the welding seam the electrode can not simply be lifted or pulled from the weld, this creates porous end craters, which weaken the weld. To correctly terminate a weld the electrode is held for a short moment at the end of the weld seam, then lifted in an arc over the just laid weld. wrong correct (Figure 8) (Figure 9) Remove slag only after it has cooled down and is no longer glowing. If an interrupted weld is to be continued, the slag at the end of the already finished weld must be removed. Then the arc can be started either in the groove or on the weld, as described earlier, and then moved to the end of the weld, which has to be thoroughly melted for good fusion. Welding is then continued normally. 6 TIG Welding (optional) Due to the same welding characteristics as with manual arc welding, TIG welding is possible with models Invert 130/40 and 130/60. For TIG welding a TIG torch model SR 17 V (see section 11) is used, which is always connected to the negative (-) pole. The arc is started by scratching with the tungsten electrode on the workpiece (causing a short-circuit). The shielding gas is supplied directly from the pressure reducing device of the gas cylinder to the torch. A gas flow rate of 6-7 l/min is recommended. Pure argon is required as shielding gas. The earth lead is connected to socket [4]. The welding current is selected with the potentiometer [2], then the arc is ignited by a brief contact of the tungsten electrode with the workpiece (scratch ...

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