Fundamentals of MIG Welding and Techniques Table Review

Welding Question Push or forhand technique pros Backhand or Pull technique pros Occilation Frequency Spray weld Pulse Technique Stubbing Explain what each letter or number refers to in the following ER70S6 What does MIG stand for 6 things needed for MIG welding In MIG welding explain power source What shielding gasses are commonly used in MIG Modes of metal transfer in MIG What does GMAW stand for Describe Short circuit transfer method The advantage of using a constant voltage machine is Which shielding gas gives the best cleaning action, crossdraft protection, and the lowest overall cost? A flowmeter measures and controls the ____ of the gas flow. When selecting a nozzle for GTAW or GMAW, what determines the nozzle diameter? Which shielding gas produces the deepest penetration when GMAW on carbon and low-alloy steel? What number filter lens is recommended for use with GTAW, GMAW, and FCAW? The polarity used with almost all GMAW applications is ____. Which of the following is not a GMAW metal transfer method? a. Short circuit. b. Solid metal. c. Spray. d. Globular. In the spray transfer method of metal transfer, the metal travels across the arc as ____. Spray transfer occurs when the current is set above the ____ point. Spray transfer will occur only when the percentage of argon in the mixture is above ____ percent. When the electrode wire bunches up in the wire feeder, it is called a ____. To feed the electrode wire through the cable to the torch, the ____ switch is used. Answer Flat welds Controls speed Good for filling Movement of gun in a continuous pattern How many oscillations in an inch of weld Uses 90% argon gas Only used in flat or horizontal welds Allows to spray weld vertically by pulsing current so metal cools slightly between pulses of current Excess material breaking off and melting to materials E-electrode R-rod 70-tensile strength S-solid. (this refers to the state and can be I either S for solid or C for core) 6- class of metal Metal Inert Gas 1 power source 2 shielding gas 3 regulator- sets gas flow cubic feet per hour 4 feeder 5 whip/gun 6 wire.023 .052 common size Constant voltage ( keeps metal melting at same rate) DCRP- Direct Current Reverse Polarity A rectifier is used to reverse polarity Carbon dioxide Argon Helium Short circut- 14-21v Globular-21-21.3v Spray Pulased arc- also known as GMAW Gas Metal Arc Welding Electrode metal touches base metal short circuting in an arc and melting electode wire that is fed at a continuous pace. Cycle can repeat between 20 and 250 times a second small percentage change in voltage leads to a large percentage change in current Argon. volume The volume of gas and the size of the joint opening. carbon dioxide 10-14 DCEP b fine metal droplets transition 90 birds nest inch Which of the following statements is not true for GMAW? a. It can be used in all positions. b. It can be used to weld magnesium. c. It can be used to weld all commercially important metals. d. It is also known as TIG welding. Which of the following statements is not true for GMAW with a short circuiting arc? a. The weld pool cools slowly. b. There is no metal transfer through the arc. c. It works in all welding positions. d. It works on metal in the overhead position. When using short circuiting metal transfer, what causes the metal droplet to leave the electrode wire? The pulsed spray transfer method uses the peak current for welding. The background current is used to ____ the arc. When GMAW, changing the wire feed speed changes the ____. Why is it possible and desirable to use a narrower groove when V-groove butt welding with GMAW or FCAW than with SMAW? In FCAW or GMAW, the welder must maintain the ____. The end of a GMA or FCA weld should be shielded while it cools by ____. Which transfer method is very effective at filling large gaps between poorly fitted parts and is appropriate for performing GMAW in the overhead position? When the edge melts too quickly while doing a lap joint, the welder should ____. What information is obtained from the first two or three digits of an AWS electrode classification number? The ____ is revealed by the last two digits of the AWS electrode classification number The suggested welding position for an electrode is indicated by the ____ digit from the right in the AWS electrode classification A number ____ filter lens is recommended for SMAW A(n) ____ arc welding machine may consist of a DC rectifier and an alternator A DCEP electrode has the same direction of flow as an electrode with a ____ designation What duty cycle is recommended for a welding machine that is to be used with automatic or semi-automatic welding? The approximate temperature of the SMAW arc is ____ F (3593 C – 3871 C). The average no-load voltage in a DC arc welding circuit is ____ volts. factors in determining the polarity of the circuit while welding are What may be the result if a person receives an arc flash? The weaving bead width should be ____ the diameter of the electrode being used A flip motion is used to ____. Where should a weld be restarted on a previously unfinished bead? Undercut in a horizontal inside corner joint usually is a(n) ____ Gravity causes the metal in the arc to fall as it travels across the arc. What may be done to reduce this d a The surface tension of the pool and pinch force maintain amount of current FCAW and GMAW penetrate more than SMAW. Narrow grooves take less welding metal. Narrow grooves are cheaper to make. nozzle-to-work distance c. holding the nozzle at the end of the weld during the postflow of the shielding gas short circuit point the electrode more toward the surface The tensile strength of the electrode. the composition of the electrode coating 2nd 10-14 AC/DC DCRP 100% 6500–7000 60-80 The rate at which you wish to deposit the filler metal The type of base metal The position of the joint The person may be temporarily blinded. The person may see white spots for a time. Permanent damage to the retina may occur. 6 times allow the weld time to cool At the leading edge of the previous bead. depression along the upper edge of the weld on the vertical piece Decrease the arc gap slightly. tendency while welding in the horizontal, vertical, or overhead positions? ____ will help prevent undercutting Stopping momentarily at the upper end of each electrode movement Welding machines used for GMAW or FCAW must be constant-____________________ type machines To reduce spatter, stabilize the arc, and improve metal transfer during GMAW operations, carbon dioxide and/or ____________________ may be added to argon. Argon has a lower heat ____________________ than helium Adding small quantities of ____________________ to argon gas will greatly reduce spatter and help to stabilize the arc. The development of the constant ____________________ welding machine made the use of GMAW more practical. When GMAW or FCAW, the welder must control the welding speed, the nozzle-to-work distance, and the ____________________. The type of current that flows from the electrode across the arc to the work is called ____________________. The constant ____________________ machine is most desirable when doing manual arc welding DCRP has the same direction of electron flow as ____________________. When using a constant current machine, if the arc gap increases, the resistance will ____________________. Each bead is cleaned before the next bead is made to prevent ____________________ inclusions voltage small electrodes are used for-------- Used on thin metal Used in overhead welding. Used on the root pass of a weld on thick metal Used to deposit larger amounts filler metal Used on single pass welds on thick metal section Large Diameter Electrodes are used for-----T/F FCAW may be used without a pressurized shielding gas T/F GMAW can be used on all commercially important metals T/F GMAW can be used in all positions. T/F In globular transfer, the metal moves across the arc in the form of large drops T/F Good ventilation is especially important when using CO2 gas T/F Chlorinated hydrocarbon solvents left on metal surfaces will form phosgene (a poisonous, highly toxic gas) at welding temperatures T/F GMAW can be done only when using DCEP. T/F Both GMAW and FCAW may be semi-automatic or automatic processes T/F SMAW and GMAW use constant current arc welding machines T/F One advantage of a constant current arc welder is that a large percentage change in voltage results in a small percentage change in amperage. T/F The length of the arc welding cables generally has little or no effect on the weld being made. T/F The materials in the flux covering on an electrode determine the electrical characteristics of the electrode. T/F Using a CC welding machine, the amount of amperage will increase if the connections at the work or electrode holder are loose. T/F A stringer bead width should be 2-3 times the electrode diameter. oxygen conductivity oxygen voltage torch electrode angle DCEN DCSP current DCEP increase slag T T T T T T T T F T F T F T T/F The flat position is the best position in which to weld any joint. T/F When multiple beads are used, it is not always necessary to remove slag between beads T/F The reversal of current in an AC circuit virtually eliminates arc blow Explain why the flow rate of the shielding gas must be increased when welding in the vertical, horizontal, or overhead positions. T F T The shielding gas falls away from the joint area due to gravity, so more gas is required. The trigger is pulled on the gun and the electrode feeds until it touches the base metal. The arc is struck when contact is made semi-automatic welding, the welder controls the What is the difference between semi-automatic welding In welding gun; in automatic welding, the machine and automatic welding? controls the gun A commercial anti-spatter compound is sprayed in and How is spatter kept from sticking to the nozzle? on the nozzle What is the typical no-load open circuit voltage of a DC 60–80 volts arc welding machine? How is the current in an AC welding machine changed to The AC is passed through a rectifier and changed to DC DC? Produce a shielding gas to protect the metal from oxidation. Provide fluxing agents. Produce a solidified List five functions of the flux coating on a SMAW slag covering over weld bead while it cools. Slag allows electrode the weld to cool slowly. Establish polarity and electrical characteristics of electrode. The percentage of time in a ten-minute timeframe that Describe the term "duty cycle." a welding machine can be used at its rated output current How does the welder know what type electrode he/she is The electrode number is printed on the flux covering at using? the bare end of the electrode. A magnetic field around the DC electrode which tends What is arc blow? to deflect or blow the arc stream forward or backward At the end of the joint the electrode direction is Explain exactly how you would move your electrode to reversed as the electrode is lifted. The finishing crater properly end a weld bead at the end of the joint should be filled just as the arc is broken. Explain how the arc is struck when GMAW or FCAW. Why should a covered electrode never be bent? List at least five factors that the welder must control to obtain a good weld when doing SMAW. type(s) of current used for GTAW (TIG) What is the constant in TIG, voltage or current? what is the benefit of DCEN in TIG what is the benefit of DCEP in TIG what is the benefit of increasing AC frequency in TIG? What is the benefit of decreasing AC frequency in TIG? What are the 5 main components of a GTAW torch? what metals would you weld with a green banded electrode? (pure Tungsten) what precautions should be given when shaping a Thoriated tungsten electrode? what does adding 2% Thorium to a tungsten electrode do? what colour band does a 2% Thoriated Tungsten Electrode have? what colour band does a1% Thoriated electrode have? The covering will crack and poor welds will result. The arc gap length, welding current, speed of forward motion, electrode angle or position, penetration, weld width, and the bead contour DCEP DCEN and alternating. Current cleans-removes oxides from metal surfaces increases arc force allowing for better penetration increasing the value will squeeze the arc narrower which promotes greater arc stability and a shallower bead (great for fine precision work) lowering this value increases the arc width and promotes greater weld penetration the torch body, a collet holder and collet , the end cap, and the nozzle Aluminum and magnesium do not inhale dust as it is radioactive the adding of Thorium effectively double their current carrying capacity. electrodes start easily and resist contamination well red Yellow what colour band does a2% Lanthanated Tungsten have? Blue hares the characteristics of Thoriated electrodes, they what are the properties of a 2% lanthanated tungsten? also ball well in A/C making them a good choice for general shop use What colour band is 1.5% Lanthanated gold What colour band is 1% Lanthanated black What colour band is 2%Ceriated Tungsten orange What colour band is Zirconiated Tungsten brown is an electrode perfect for both A/C or D/C, they can what are the properties of a 2%Ceriated Tungsten run for prolonged periods, start well, resist contamination, precision work on thin metals used to weld Aluminum and Magnesium where the highest quality is necessary, these tungsten’s replace what are the properties of a Zirconated Tungsten? the pure variety due to higher amperage carrying capability, and they are used with the balled end. amperage for air cooled TIG torch not more than 200amps water cooled TIG torch amperage range 200 amps + TIG electrode size range 0.010" to 1/4" helps arc jump the gap Steele turns off, Aluminum stays role of high frequency current? on starts gas flowing before weld starts- clears What does pre flow do? contaminants what does The balance control on an invertors allow allow the operator to reconfigure the a/c wave length PPS means? pulse per second peak % of total amps 45% ( how long is it at peak Peak Percentage? amperage)