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Weld 1054 17F
Welding
| Question | Answer |
|---|---|
| Push or forhand technique pros | Flat welds Controls speed |
| Backhand or Pull technique pros | Good for filling |
| Occilation | Movement of gun in a continuous pattern |
| Frequency | How many oscillations in an inch of weld |
| Spray weld | Uses 90% argon gas Only used in flat or horizontal welds |
| Pulse Technique | Allows to spray weld vertically by pulsing current so metal cools slightly between pulses of current |
| Stubbing | Excess material breaking off and melting to materials |
| Explain what each letter or number refers to in the following ER70S6 | 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 |
| What does MIG stand for | Metal Inert Gas |
| 6 things needed for MIG welding | 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 |
| In MIG welding explain power source | Constant voltage ( keeps metal melting at same rate) DCRP- Direct Current Reverse Polarity A rectifier is used to reverse polarity |
| What shielding gasses are commonly used in MIG | Carbon dioxide Argon Helium |
| Modes of metal transfer in MIG | Short circut- 14-21v Globular-21-21.3v Spray Pulased arc- also known as GMAW |
| What does GMAW stand for | Gas Metal Arc Welding |
| Describe Short circuit transfer method | 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 |
| The advantage of using a constant voltage machine is | small percentage change in voltage leads to a large percentage change in current |
| Which shielding gas gives the best cleaning action, cross-draft protection, and the lowest overall cost? | Argon. |
| A flowmeter measures and controls the ____ of the gas flow. | volume |
| When selecting a nozzle for GTAW or GMAW, what determines the nozzle diameter? | The volume of gas and the size of the joint opening. |
| Which shielding gas produces the deepest penetration when GMAW on carbon and low-alloy steel? | carbon dioxide |
| What number filter lens is recommended for use with GTAW, GMAW, and FCAW? | 10-14 |
| The polarity used with almost all GMAW applications is ____. | DCEP |
| Which of the following is not a GMAW metal transfer method? a. Short circuit. b. Solid metal. c. Spray. d. Globular. | b |
| In the spray transfer method of metal transfer, the metal travels across the arc as ____. | fine metal droplets |
| Spray transfer occurs when the current is set above the ____ point. | transition |
| Spray transfer will occur only when the percentage of argon in the mixture is above ____ percent. | 90 |
| When the electrode wire bunches up in the wire feeder, it is called a ____. | birds nest |
| To feed the electrode wire through the cable to the torch, the ____ switch is used. | 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. | d |
| 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. | a |
| When using short circuiting metal transfer, what causes the metal droplet to leave the electrode wire? | The surface tension of the pool and pinch force |
| The pulsed spray transfer method uses the peak current for welding. The background current is used to ____ the arc. | maintain |
| When GMAW, changing the wire feed speed changes the ____. | amount of current |
| Why is it possible and desirable to use a narrower groove when V-groove butt welding with GMAW or FCAW than with SMAW? | FCAW and GMAW penetrate more than SMAW. Narrow grooves take less welding metal. Narrow grooves are cheaper to make. |
| In FCAW or GMAW, the welder must maintain the ____. | nozzle-to-work distance |
| The end of a GMA or FCA weld should be shielded while it cools by ____. | c. holding the nozzle at the end of the weld during the postflow of the shielding gas |
| Which transfer method is very effective at filling large gaps between poorly fitted parts and is appropriate for performing GMAW in the overhead position? | short circuit |
| When the edge melts too quickly while doing a lap joint, the welder should ____. | point the electrode more toward the surface |
| What information is obtained from the first two or three digits of an AWS electrode classification number? | The tensile strength of the electrode. |
| The ____ is revealed by the last two digits of the AWS electrode classification number | the composition of the electrode coating |
| The suggested welding position for an electrode is indicated by the ____ digit from the right in the AWS electrode classification | 2nd |
| A number ____ filter lens is recommended for SMAW | 10-14 |
| A(n) ____ arc welding machine may consist of a DC rectifier and an alternator | AC/DC |
| A DCEP electrode has the same direction of flow as an electrode with a ____ designation | DCRP |
| What duty cycle is recommended for a welding machine that is to be used with automatic or semi-automatic welding? | 100% |
| The approximate temperature of the SMAW arc is ____F (3593C – 3871C). | 6500–7000 |
| The average no-load voltage in a DC arc welding circuit is ____ volts. | 60-80 |
| factors in determining the polarity of the circuit while welding are | The rate at which you wish to deposit the filler metal The type of base metal The position of the joint |
| What may be the result if a person receives an arc flash? | The person may be temporarily blinded. The person may see white spots for a time. Permanent damage to the retina may occur. |
| The weaving bead width should be ____ the diameter of the electrode being used | 6 times |
| A flip motion is used to ____. | allow the weld time to cool |
| Where should a weld be restarted on a previously unfinished bead? | At the leading edge of the previous bead. |
| Undercut in a horizontal inside corner joint usually is a(n) ____ | depression along the upper edge of the weld on the vertical piece |
| Gravity causes the metal in the arc to fall as it travels across the arc. What may be done to reduce this tendency while welding in the horizontal, vertical, or overhead positions? | Decrease the arc gap slightly. |
| ____ 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 | voltage |
| To reduce spatter, stabilize the arc, and improve metal transfer during GMAW operations, carbon dioxide and/or ____________________ may be added to argon. | oxygen |
| Argon has a lower heat ____________________ than helium | conductivity |
| Adding small quantities of ____________________ to argon gas will greatly reduce spatter and help to stabilize the arc. | oxygen |
| The development of the constant ____________________ welding machine made the use of GMAW more practical. | voltage |
| When GMAW or FCAW, the welder must control the welding speed, the nozzle-to-work distance, and the ____________________. | torch electrode angle |
| The type of current that flows from the electrode across the arc to the work is called ____________________. | DCEN DCSP |
| The constant ____________________ machine is most desirable when doing manual arc welding | current |
| DCRP has the same direction of electron flow as ____________________. | DCEP |
| When using a constant current machine, if the arc gap increases, the resistance will ____________________. | increase |
| Each bead is cleaned before the next bead is made to prevent ____________________ inclusions | slag |
| small electrodes are used for-------- | Used on thin metal Used in overhead welding. Used on the root pass of a weld on thick metal |
| Large Diameter Electrodes are used for------ | Used to deposit larger amounts filler metal Used on single pass welds on thick metal section |
| T/F FCAW may be used without a pressurized shielding gas | T |
| T/F GMAW can be used on all commercially important metals | T |
| T/F GMAW can be used in all positions. | T |
| T/F In globular transfer, the metal moves across the arc in the form of large drops | T |
| T/F Good ventilation is especially important when using CO2 gas | T |
| T/F Chlorinated hydrocarbon solvents left on metal surfaces will form phosgene (a poisonous, highly toxic gas) at welding temperatures | T |
| T/F GMAW can be done only when using DCEP. | T |
| T/F Both GMAW and FCAW may be semi-automatic or automatic processes | T |
| T/F SMAW and GMAW use constant current arc welding machines | F |
| 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 |
| T/F The length of the arc welding cables generally has little or no effect on the weld being made. | F |
| T/F The materials in the flux covering on an electrode determine the electrical characteristics of the electrode. | T |
| T/F Using a CC welding machine, the amount of amperage will increase if the connections at the work or electrode holder are loose. | F |
| T/F A stringer bead width should be 2-3 times the electrode diameter. | T |
| T/F The flat position is the best position in which to weld any joint. | T |
| T/F When multiple beads are used, it is not always necessary to remove slag between beads | F |
| T/F The reversal of current in an AC circuit virtually eliminates arc blow | T |
| Explain why the flow rate of the shielding gas must be increased when welding in the vertical, horizontal, or overhead positions. | The shielding gas falls away from the joint area due to gravity, so more gas is required. |
| Explain how the arc is struck when GMAW or FCAW. | 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 |
| What is the difference between semi-automatic welding and automatic welding? | In semi-automatic welding, the welder controls the welding gun; in automatic welding, the machine controls the gun |
| How is spatter kept from sticking to the nozzle? | A commercial anti-spatter compound is sprayed in and on the nozzle |
| What is the typical no-load open circuit voltage of a DC arc welding machine? | 60–80 volts |
| How is the current in an AC welding machine changed to DC? | The AC is passed through a rectifier and changed to DC |
| List five functions of the flux coating on a SMAW electrode | Produce a shielding gas to protect the metal from oxidation. Provide fluxing agents. Produce a solidified slag covering over weld bead while it cools. Slag allows the weld to cool slowly. Establish polarity and electrical characteristics of electrode. |
| Describe the term "duty cycle." | The percentage of time in a ten-minute timeframe that a welding machine can be used at its rated output current |
| How does the welder know what type electrode he/she is using? | The electrode number is printed on the flux covering at the bare end of the electrode. |
| What is arc blow? | A magnetic field around the DC electrode which tends to deflect or blow the arc stream forward or backward |
| Explain exactly how you would move your electrode to properly end a weld bead at the end of the joint | At the end of the joint the electrode direction is reversed as the electrode is lifted. The finishing crater should be filled just as the arc is broken. |
| Why should a covered electrode never be bent? | The covering will crack and poor welds will result. |
| List at least five factors that the welder must control to obtain a good weld when doing SMAW. | The arc gap length, welding current, speed of forward motion, electrode angle or position, penetration, weld width, and the bead contour |
| type(s) of current used for GTAW (TIG) | DCEP DCEN and alternating. |
| What is the constant in TIG, voltage or current? | Current |
| what is the benefit of DCEN in TIG | cleans-removes oxides from metal surfaces |
| what is the benefit of DCEP in TIG | increases arc force allowing for better penetration |
| what is the benefit of increasing AC frequency in TIG? | increasing the value will squeeze the arc narrower which promotes greater arc stability and a shallower bead (great for fine precision work) |
| What is the benefit of decreasing AC frequency in TIG? | lowering this value increases the arc width and promotes greater weld penetration |
| What are the 5 main components of a GTAW torch? | the torch body, a collet holder and collet , the end cap, and the nozzle |
| what metals would you weld with a green banded electrode? (pure Tungsten) | Aluminum and magnesium |
| what precautions should be given when shaping a Thoriated tungsten electrode? | do not inhale dust as it is radioactive |
| what does adding 2% Thorium to a tungsten electrode do? | the adding of Thorium effectively double their current carrying capacity. electrodes start easily and resist contamination well |
| what colour band does a 2% Thoriated Tungsten Electrode have? | red |
| what colour band does a1% Thoriated electrode have? | Yellow |
| what colour band does a2% Lanthanated Tungsten have? | Blue |
| what are the properties of a 2% lanthanated tungsten? | hares the characteristics of Thoriated electrodes, they 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 |
| what are the properties of a 2%Ceriated Tungsten | is an electrode perfect for both A/C or D/C, they can run for prolonged periods, start well, resist contamination, precision work on thin metals |
| what are the properties of a Zirconated Tungsten? | used to weld Aluminum and Magnesium where the highest quality is necessary, these tungsten’s replace 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" |
| role of high frequency current? | helps arc jump the gap Steele turns off, Aluminum stays on |
| What does pre flow do? | starts gas flowing before weld starts- clears 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 Percentage? | peak % of total amps 45% ( how long is it at peak amperage) |
Created by:
Neeneral