Define the term duty cycle

Assignment Help Mechanical Engineering

Reference no: EM131003621

1A. What is the typical no-load open circuit voltage of a DC arc welding machine?

1B. How is the current in an AC welding machine changed to DC?

1C. List the three components of the transformer type arc welding machine.

1D. Describe the difference between a diode and a silicon-controlled rectifier.

1E. Which DC electrical polarity requires a larger electrode diameter, DCEP or DCEN?

2A. Define the term duty cycle.

2B. How does a welder know what type of electrode he/she is using?

2C. What is arc blow?

2D. What special precautions must be taken if the welding leads must be temporarily run across an aisle?

2E. Explain exactly how you would move your electrode to properly end a weld bead at the end of the joint.

3A. List two reasons why a small diameter gas nozzle would be used.

3B. List two reasons for rapid tungsten electrode consumption.

3C. Define downslope. Why is downslope used or necessary?

3D. If the flowmeter was not completely closed when the station was shut down, what might happen when the station is reopened?

3E. Explain why the flow rate of a shielding gas must be increased for welding in the vertical, horizontal, or overhead positions.

4A. Why is the area above 15 psig (103kPa) often marked with a red band on an acetylene low-pressure regulator?

4B. List four methods of preventing or compensating for shrinkage when making a butt weld joint.

4C. Why is a whipping motion used for welding out of position?

5A. List the five variables in resistance welding.

5B. List the five main parts of a resistance welding machine.

5C. List three requirements for resistance welding electrodes.

5D. What is the basic principle of all resistance welding?

5E. List the four greatest resistance welding dangers.

6A. To what temperature should gray cast iron be preheated for oxyfuel gas welding?

6B. What are the three 3-digit numbers assigned to the AISI stainless steel groups?

6C. List the four general classifications of stainless steel.

6D. List the four types of cast iron.

6E. List four things that are necessary to produce a good weld on plastics.

7A. Why should hydrogen pickup be eliminated or reduced during the welding of high-carbon and alloy steels?

7B. Define hot shortness.

7C. When GTAW or GMAW is performed on a pipe or tube, how can the root of the weld be protected from contamination?

7D. List six common welding defects that occur in a pipe weld.

7E. What is the advantage of "walking the cup" when creating a root pass with the GTAW process?

8A. What causes the bends?

8B. Name the six axes of motion typically used on an articulated robot.

8C. List five main items of equipment for a robot workcell.

8D. How are workers prevented from walking into a robot's working volume?

8E. List two types of electrical actuators used on an electrically operated robot.

9A. What three materials, in addition to air, are used in a blast furnace to produce pig iron?

9B. List the five major functions of a blast furnace.

9C. What is used to blow oxygen into the furnace during the basic oxygen process?

9D. Gases formed in a vacuum furnace are pulled away from the molten metal by the vacuum pumps. List three qualities of steel that are improved by this process.

9E. What type of current is used in the induction heating process?

10A. What is meant by the term alloy steel?

10B. List five methods of identifying a metal.

10C. What four characteristics of the spark in a spark test denote the nature and condition of the steel?

10D. What does AISI stand for?

10E. Describe the two regions in the heat affected zone and how they are formed.

11A. Describe the steps in the quench and temper process.

11B. Identify one hardening method that will produce a gear with a hard surface and a tough interior.

11C. Identify the type of heat treatment applied to an aluminum alloy with a T6 designation.

12A. When does a flaw become a defect?

12B. What happens to the sides of a small crack when a magnetic field is applied to the metal?

12C. Name three types of laboratory tests that are not normally performed in a small shop situation.

12D. Name three types of tests used to evaluate hardness.

12E. In the correct order, list the six steps required to perform a dye penetrant inspection.

13A. Explain why offices, restrooms, and cafeterias should be located away from the shop area.

13B. Explain the common reasons many new welding shops fail.

13C. Identify important features of a building to be used for a welding shop.

13D. Why is it important to have adequate ventilation in a shop?

13E. List four factors to consider when estimating the final cost of fabricating an item.

14A. Why is submerged arc welding called "submerged"?

14B. Why is the thermite welding process considered to be safe?

14C. List four advantages of ultrasonic welding.

14D. List at least five factors that the welder must control to obtain a good weld when doing SMAW.

14E. Describe lock-out, tag-out procedures performed when a machine is turned off for maintenance work.

15A. List the five basic weld joints.

15B. List the four welding positions in which the five basic weld joints are made.

15C. List five functions of the flux coating on a SMAW electrode.

15D. List five variables that influence the decision to use DCEN or DCEP.

Reference no: EM131003621

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