107 lines
4.6 KiB
Plaintext
107 lines
4.6 KiB
Plaintext
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WELDING-Wire
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M.I.G.(Metal Inert Gas) - Points to Remember
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1. Mig (GMAW) welding is often referred to
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by the manufacturer's trade name as Micro-wire,
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Aircomatic, Sigma, and Millermatic Welding.
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2. Mig welding is faster than stick electrode
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welding and is much easier to learn.
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3. Spray transfer type of welding is particu-
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larly adapted for welding heavy gage metals.
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4. Short circuiting transfer welding is best
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for welding light gage metals.
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5. For optimum efficiency, DCRP current is
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required for Mig welding.
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6. For Mig welding, a constant potentiaI
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power supply with a nearly flat volt-ampere char-
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acteristic produces the best results.
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7. As a general rule, an air-cooled gun is
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satisfactory when welding with amperage
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around 200 and a water-cooled gun for welding
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heavy metals requiring higher amperages.
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8. The use of CO2 as a shielding gas is most
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effective and less expensive when welding steel.
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9. Argon or a mixture of argon and oxygen
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will produce the most effective results in welding
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aluminum and stainless steel.
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10. The rate of gas flow for welding most
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metals is approximately 35 cu ft/hr. However,
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this rate may have to be varied somewhat, de-
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pending on the type, electrode size, and thick-
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ness of metal.
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11. The effectiveness of the shielding gas is
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often governed by the distance of the gun from
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the workpiece. Generally the gas nozzle should
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not be spaced more than 2" from the workpiece.
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12. The use of correct diameter wire electrode
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is necessary for good welds. Check recommen-
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dations for correct electrode diameters.
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13. The correct current for welding must often
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be determined by trial. Check recommendations
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for starting current.
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14. Be sure the wire feed is set for the amper-
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age which is to be used for welding.
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15. For most Mig welding applications, the
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wire stick-out should be about 3/8" to 3/4".
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16. Keep the gun properly positioned to insure
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uniform weld with proper penetration.
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17. Cold laps will occur if the arc does not
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melt the base metal sufficiently.
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18. Check the weld for surface porosity. Sur-
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face porosity is usually caused by improper gas
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shielding.
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19. Do not remove the gun from the weld area
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until the puddle has solidified, otherwise cracks
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may develop.
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20. Remember, insufficient or excessive pene-
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tration is the result of failure to control heat
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input.
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