Final Exam Questions

In plasma arc welding, the recommended size of the welding orifice occasionally decreases, despite an increase in gas flow rate and amperage. Why? a. A narrower orifice is sometimes required to adequately constrict the increased level of plasma gas b. wider orifices tend to become damaged more frequently than narrower orifices c. wider orifices increase the chances of the plasma gas reacting with the shielding gas d. narrower orifices reduce the risk of double-arcing

A. A narrower orifice is sometimes required to adequately constrict the increased level of plasma gas.

Which of the following best describes the concept of double-arcing? a. an electric arc that simultaneously forms between the electrode and the nozzle as well as the nozzle and the work piece. b. an electric arc created using alternating-current instead of direct-current c. an electric arc that touches two parts of the workpiece by forking in two d. an electric arc that uses twice the recommended welding current for increased speed

A. An electric arc that simultaneously forms between the electrode and the nozzle as well as the nozzle and the work piece.

The ________ uses its cone-like shape and the Law of Charges to accelerate and squeeze electrons in the electron beam welding process. a. bias electrode b. anode c. focusing coil d. cathode

A. Bias electrode

A radiation enclosure can be made of all but which of the following materials? a. Brick b. Concreted c. Steel d. Lead

A. Brick

An electron beam is always generated in a ________ environment. a. high-vacuum b. medium-vacuum c. low-vacuum d. nonvacuum

A. High-vacuum

Prior to the application of welding heat during resistance welding, the __________ feature is used to liquefy zinc or galvanized steel in order to remove it from the metal. a. Preheat b. forging force c. quench and temper d. downslope

Preheat

What is the function of a dopant? a. To ionize gas atoms b. To improve the mechanical strength of a substance c. To alter the electrical or optical characteristics of a substance d. To produce short bursts of intense light

To alter the electrical or optical characteristics of a substance

In resistance welding, which of the following documents provides a record of all welding equipment and settings used for a given material of a given size and finish? a. Material Safety Data Sheet (MSDS) b. ANSI Z49.1 c. Welding Schedule d. All of these

Welding Schedule

When a ______________ is used, a grid power source is required. a. cathode b. triode c. diode d. anode

B. Triode.

Which of the following distinguishes laser beam welding from electrode beam welding? a. It does not produce x-radiation b. Joining is accomplished using a high energy beam c. It is accomplished without filler metal d. It is a non-contact process.

A. It does not produce x-radiation.

Choose the pneumatic or hydraulic piece of equipment that is responsible for providing the resistance welding electrode with pressure. a. rectifier b. actuators c. capacitor d. all of these

B. Actuators

_______________ must be installed to limit the laser beam's path in order to ensure that a laser beam is never directed at staff. a. Gantry systems b. Baffles c. Lead Walls d. Robotic Systems

B. Baffles

The ___________ uses electromagnetic fields to manipulate the direction of the electron beam, making it possible for the machine operator to control its path. a. anode b. deflection coil c. focusing coil d. cathode

B. Deflection coil

Which of the following is NOT a function of CNC machine? a. Program beam current b. detect joint deviation in the welding path c. preprogram beam deflection d. change beam current

B. Detect joint deviation in welding path.

Which of the following is NOT a result of prolonged, unprotected exposure to the ultraviolet light produced when a laser beam strikes a work piece? a. Blindness b. Glaucoma c. Arc Eye d. Cataracts

B. Glaucoma

Define collimated light. a. Light that is made up of one wavelength b. Light that travels parallel to one another in the same direction c. when beam of light opens up in to a wide ray d. when the crests and troughs of light waves line up

B. Light that travels parallel to one another in the same direction

The ______________ is used to set up the welding operation, inspect the weld, align the weld joint with the electron beam, and center the gun on the weld joint. a. CNC machine b. optical viewer c. seam tracker d. eccentric table

B. Optical viewer

An Excessively high gas flow rate can cause which of the following? Select all that apply. a. Premature nozzel erosion b. Porosity c. Double-arcing d. Wider weld bead

B. Porosity

Which of the following is a resistance welding process? a. Diffusion welding b. Projection welding c. Ultrasonic Welding d. Friction stir welding

B. Projection Welding The remaining are spot, seam and flash.

Plasma arc welding is less forgiving of joint misalignment than gas tungsten arc welding. Why? a. The heat of the plasma beam causes more distortion that it does with gas tungsten arc welding b. the columnar shape of the beam produces a narrower spread of heat than it does with gas tungsten arc welding c. Plasma arc welding allows for a lesser torch stand-off distance than gas tungsten arc welding, resulting in more frequent welder error d. The larger size of the plasma torch makes the welding of certain joints impossible

B. The columnar shape of the beam produces a narrower spread of heat than it does with GTAW

Which of the following is made possible by the narrow kerf widths produced by the laser beam cutting process? a. The omission of semi-durable parts b. The use of closely nested patterns c. Fast cutting speeds d. Automotive applications

B. The use of closely nested patterns

Why is the keyhole method not recommended for manual plasma arc welding? a. The required equipment to perform manual keyhole welds is generally too costly for a single individual. b. There are too many variables to manage without the aid of computerized equipment c. The keyhole method is primarily used for cutting metal and has few manual welding applications. d. Keyhole welding is only required in industrial processes not meant for a single welder.

B. There are too many variables to manage without the aid of computerized equipment.

Which of the following is NOT true of using laser beam processes on highly reflective metals? a. Reflective surfaces are harder to process using laser beam process b. To reduce laser light feedback, position the focus plane above the work piece surface c. Laser light reflected off the weld pool or work piece surface can be transmitted back through the laser optics and damage the laser itself d. to reduce laser light feedback, tilt the weldment surface a few degrees away from normal to the laser beam

B. To reduce laser light feedback, position the focus place above the work piece surface.

Which of the following CO2 lasers is the most compact and powerful? a. Fast axial-flow laser b. Transverse laser c. Slow axial-flow laser d. Diffusion-cooled laser

B. Transverse laser

In resistance welding, the phase in which current is applied to the work piece for a predetermined amount of time is referred to as ______. a. current time b. weld time c. hold time d. squeeze time

B. Weld time A is not a correct answer- there is no such thing as current time

which of these is most commonly used as sheilding gas in plasma arc welding? a. argon/helium blend b. argon c. helium d. hydrogen

B. argon

The melt-in mode for plasma arc welding is typically run at which of the following welding current ranges? a. 250-500 amperes b. 0-15 amperes c. 15-100 amperes d. 100-250 amperes

C. 15-100

From a welding perspective, plasma can best be described as ______________. a. a pressurized and superheated liquid b.a colorless fluid that is part of several liquids, including blood c. an electrically-conductive ionized gas d. an inert, amorphous solid

C. An electrically-conductive ionized gas

______________________ is the number of electrons hitting the work piece per second. a. Acceleration voltage b. Travel Speed c. Beam Current d. Beam Velocity

C. Beam current

A baffle is only required when using which of the following pumps? a. Cane pump b. Cryogenic pump c. Diffusion pump d. Molecular pump

C. Diffusion pump

Which of the following laser beam drilling methods does not require piercing? a. Single Pulse b. Trepanning c. Helical d. Percussion

C. Helical

Which of the following is NOT a result of welding in a vacuum? a. Minimized heat-affected zone b. Work chamber size restraints c. Higher weld contamination d. delays due to evacuation time

C. Higher weld contamination

Which of the following is an advantage of laser beam drilling? a. It does not create a heat-affected zone b. It produces holes with taper c. It applies low forces to the material being drilled d. It drills holes at a maximum of 2 inches deep.

C. It applies low forces to the material being drilled.

In what way is the recessed tungsten electrode in a plasma torch beneficial? Select all that apply. a. It produces more consistent touch-starts. b. It creates a hotter, more concentrated plasma beam. c. It reduces tungsten inclusions. d. It extends electrode life.

C. It reduces tungsten inclusions

Certain solvents create________________ when exposed to the ultraviolet light given off during the electron bean welding process. a. chlorinated hydrocarons b. ethyl chloride c. phosgene gas d. carbon monoxide

C. Phosgene gas

Which of the following resistance welding processes is usually cooled by an external cooling system? a. Spot welding b. Diffusion welding c. Seam welding d. friction stir welding

C. Seam welding

A horizontal rotary table permits _______________________ motion. a. horizontal linear b. vertical linear c. vertical rotary d. horizontal rotary

C. Vertical rotary

Which of the following metals is very difficult to join with the resistance welding process due to its high conductivity and low resistance? a. stainless steel b. Copper c. Aluminum d. Mild Steel

Copper

Gloves should be worn during resistance welding to safegaurd against__________________ a. electric shock b. cuts c. burns d. all of the above

D. All of the above

Which of the following variables can lead to an increased in heat during resistance welding? a. current b. resistance c. time d. all of the above

D. All of the above Remember Joule's Law: Q= (I^2)RT Heat is DIRECTLY PROPORTIONAL to resistance (R), current (I), and time (T). IF you increase any variables (I, R, or T) it will directly increase heat (Q). Same applies of you are to decrease it.

Which of the following may occur if the pressure between the electrode and the work piece drops rapidly during resistance weld time? a. the contact surfaces between the electrodes and the work pieces may overheat b. the faying surfaces of the work pieces may overheat c. the surfaces of the work pieces may vaporize d. all of the above

D. All the above

What is the function of a plane mirror? a. It allows the laser beam out of the resonator cavity. b. It closes off one end of the resonator cavity and allows the beam to bounce off it. c. It focuses the laser beam into a small spot. d. It angles the ejected laser beam down toward the work piece

D. It angles the ejected laser beam down toward the work piece

Which of the following has the highest pressure? a. high-vacuum b. low-vacuum c. medium-vacuum d. nonvacuum

D. Non vacuum

_____________ is when the electrons in a heated metal break free from their parent atom. a. stimulated emission b. heat convergence c. spontaneous emission d. thermionic emission

D. Thermionic emission

Which part of the resistance welding electrode directly determines the current and pressure densities at the weld zone? a. Electrode face b. Electrode shank c. tapers d. all of the above

Electrode Face

Resistance welding is defined as: a. a group of solid-state welding processes that produce a weld by local application of high-frequency vibratory energy as the work pieces are held together by pressure b. a group of welding process that produce coalescence of the faying surfaces from pressure and the heat obtained from the workplieces' resistance to the flow of current c. A group of solid-state welding processes that produce a weld under the compressive force contact of work pieces rotating or moving relative to one another to produce heat and plastically displace material from the faying surfaces d. a group of solid-state welding processes that produce a weld by the application of pressure at elevated temperatures with no macroscopic deformation or relative motion of the work pieces.

b. a group of welding process that produce coalescence of the faying surfaces from pressure and the heat obtained from the workplieces' resistance to the flow of current