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ITI Mechanic Auto Body Repair (AITT Theory) study materials
ITI Mechanic Auto Body Repair (AITT Theory) study resources

ITI Mechanic Auto Body Repair (AITT Theory) practice questions

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Question 1Occupational Safety, Health and Environment

When spraying a two-pack automotive paint that contains an isocyanate hardener, which health effect is the main reason supplied-air respiratory protection is specified?

  1. Bone fracture from repeated trigger operation
  2. Hearing damage caused by the spray gun's high airflow
  3. Respiratory sensitization leading to occupational asthma Correct answer.
  4. Permanent colour blindness caused by pigment absorption

Explanation

Isocyanate hardeners are potent respiratory sensitizers; once a worker is sensitized, even very low subsequent exposures can trigger severe asthma attacks. Supplied-air respirators isolate the painter from isocyanate vapour and mist because air-purifying cartridges are not considered adequate protection for isocyanates. The other listed effects are not the recognised primary hazard of isocyanate exposure.

Question 2Occupational Safety, Health and Environment

A puddle of solvent-based paint thinner ignites on the shop floor. Which class of portable extinguisher is designed for this type of flammable-liquid fire?

  1. Class C
  2. Class A
  3. Class D
  4. Class B Correct answer.

Explanation

Class B extinguishers are rated for flammable liquids and gases such as paint thinner, solvents and fuel. Class A is for ordinary combustibles, Class C for energized electrical equipment, and Class D for combustible metals. Using a water-type Class A extinguisher on a solvent fire can spread the burning liquid.

Question 3Occupational Safety, Health and Environment

Before decanting a new thinner into a smaller container, where should the mechanic confirm the flash point, required PPE and spill-response measures?

  1. In the product safety data sheet Correct answer.
  2. On the shop job card
  3. On the supplier invoice
  4. In the vehicle manufacturer's repair manual

Explanation

The safety data sheet is the primary workplace document for a hazardous chemical's flash point, health effects, PPE, first aid and spill response. The product label gives a brief warning, but the SDS carries the detailed information needed before decanting. Invoices and job cards are not hazard-communication documents.

Question 4Occupational Safety, Health and Environment

In a body shop, an oxygen cylinder and an acetylene cylinder are kept in the same storage area. What minimum separation is normally required between them?

  1. 50 ft (15 m) in every case
  2. 10 ft (3 m) with no barrier required
  3. 20 ft (6 m) or a 5 ft noncombustible barrier Correct answer.
  4. 5 ft (1.5 m) with no barrier required at any time

Explanation

Oxygen supports combustion and acetylene is a fuel gas, so storing them together without separation increases the risk of a severe fire or explosion. Common fire-code practice is to separate oxygen and fuel-gas cylinders by at least 20 ft or by a noncombustible barrier at least 5 ft high with a fire rating of at least one-half hour. Chaining cylinders individually and closing valves are also required storage practices.

Question 5Occupational Safety, Health and Environment

Which statement best describes the main safety function of a downdraft spray booth during basecoat application?

  1. It raises the flash point of the paint
  2. It sweeps overspray and vapour away from the breathing zone Correct answer.
  3. It cools the paint surface to extend the mixed product's pot life
  4. It removes the need for the painter to wear a respirator

Explanation

A downdraft booth is an engineering control that sweeps air downward, carrying paint mist and solvent vapour away from the technician and out through filtered exhaust. It reduces exposure but does not eliminate the need for the correct respirator and skin protection. Ventilation cannot change the paint's flash point or pot life in the way described.

Question 6Occupational Safety, Health and Environment

A technician must move a heavy front bumper from a bench to a trolley. Which lifting technique is recommended?

  1. Bend at the waist with straight legs and lift quickly
  2. Lift with one hand while bracing the other on the bench
  3. Keep the load close, bend the knees, and do not twist Correct answer.
  4. Keep the bumper away from the body and twist at the waist

Explanation

Keeping the load close reduces the lever arm on the lower back, and bending the knees lets the leg muscles do the lifting. Twisting while under load is a common cause of back injury, so the technician should turn by moving the feet. A two-person lift or a mechanical aid should be used if the bumper exceeds a safe individual lift.

Question 7Occupational Safety, Health and Environment

Arc welding or grinding on galvanized steel can expose the technician to which specific fume hazard?

  1. Silica dust from the zinc layer
  2. Zinc oxide fume causing metal fume fever Correct answer.
  3. Carbon monoxide only, with no metal fume
  4. Asbestos fibres released from the galvanized coating

Explanation

Galvanized steel carries a zinc coating, and welding or grinding vaporizes the zinc into fine oxide fume. Inhaling this fume can cause metal fume fever, with flu-like symptoms, and repeated overexposure can cause more serious respiratory effects. Local exhaust ventilation and appropriate respiratory protection are needed, and the zinc coating should be removed from the weld area where practicable.

Question 8Occupational Safety, Health and Environment

When spraying solvent-based basecoat in a spray booth, which respirator filter is selected for the solvent vapour?

  1. A nuisance-dust mask
  2. A P100 particulate filter
  3. An acid-gas cartridge
  4. An organic-vapour cartridge Correct answer.

Explanation

Organic-vapour cartridges contain adsorbent media for solvents such as those in automotive basecoats and thinners. A particulate filter captures mist and dust but lets solvent vapour pass through, while a nuisance-dust mask offers no protection against vapours. Cartridge selection must also match the full product hazard; isocyanate-containing clearcoats require supplied air rather than an air-purifying cartridge.

Question 9Occupational Safety, Health and Environment

Which action is the correct way to remove body dust from a technician's clothing before leaving the repair area?

  1. Brush the clothing with a dry paintbrush
  2. Shake the clothing vigorously in the booth
  3. Vacuum the clothing with a HEPA-filtered vacuum Correct answer.
  4. Blow off the clothing with compressed air at 90 psi

Explanation

A HEPA-filtered vacuum captures fine dust instead of dispersing it into the air, reducing inhalation and cross-contamination. Compressed air is especially dangerous because it can force dust deep into the lungs and can inject air through the skin if directed at the body. Shaking or dry brushing simply re-suspends the dust in the breathing zone.

Question 10Occupational Safety, Health and Environment

After oxy-acetylene cutting or welding is finished in a collision repair bay, what fire-watch period is commonly required by hot-work practice?

  1. 5 minutes
  2. 10 minutes
  3. 30 minutes Correct answer.
  4. 60 minutes

Explanation

A fire watch is required during hot work and must continue afterward because smouldering material can take time to develop into a fire. Common hot-work practice, such as NFPA 51B, requires a fire watch for at least 30 minutes after the work is completed. The area should also be examined for concealed smouldering before the watch is ended.

Question 11Occupational Safety, Health and Environment

Prolonged use of pneumatic hammers and angle grinders in a body shop exposes the technician to which health effect caused by high sound levels?

  1. Arc flash burns to the eyes
  2. Vibration white finger in the hands
  3. Contact dermatitis from metal dust
  4. Noise-induced hearing loss Correct answer.

Explanation

Sustained exposure to high sound pressure levels from pneumatic and grinding tools damages the hair cells of the inner ear, and the loss is cumulative and irreversible. Hearing protection matched to the noise level must be worn whenever these tools are running.

Question 12Occupational Safety, Health and Environment

A technician uses an angle grinder to strip paint and dress weld seams. Which eye and face protection is appropriate for this task?

  1. No eye protection provided the guard is in place
  2. Safety glasses alone
  3. A face shield alone with no glasses
  4. A face shield worn over safety glasses Correct answer.

Explanation

Grinding throws high-speed particles from many angles, and a face shield alone leaves gaps at the sides and below. Safety glasses should be worn under a face shield so that small particles are stopped even if they pass the shield.

Question 13Occupational Safety, Health and Environment

A technician raises the front of a vehicle with a floor jack to inspect the exhaust system. What must be done before any part of the body goes under the vehicle?

  1. Ask a second person to hold the jack handle steady
  2. Chock the rear wheels and then lower the jack slowly
  3. Place rated jack stands under the specified lift points Correct answer.
  4. Leave the jack in place with the handle locked

Explanation

A floor jack is a lifting device, not a support; it can creep or fail once it is holding load. Rated jack stands placed under the manufacturer's lift points carry the load mechanically and allow safe work underneath.

Question 14Occupational Safety, Health and Environment

A portable electric grinder is found with a deep cut in its power cord exposing the inner conductors. What is the correct action?

  1. Wrap the damaged section with electrical tape and continue
  2. Use it only for short bursts until the job is finished
  3. Plug it into a residual current device and use it carefully
  4. Withdraw it from service and tag it for repair Correct answer.

Explanation

A cord with exposed conductors can cause electric shock or arc flash, and tape is not a repair. The tool must be withdrawn from service, the plug removed or locked out, and the cord replaced by a competent person before reuse.

Question 15Occupational Safety, Health and Environment

After a solvent-based basecoat wipe-down, the used rags are placed in an open plastic bucket. What is the correct way to handle these rags at the end of the shift?

  1. Keep them in the open bucket until the next morning
  2. Place them in a self-closing metal waste can Correct answer.
  3. Seal them in a cardboard box for general waste
  4. Lay them flat on the floor so the solvent evaporates

Explanation

Solvent-soaked rags can self-heat and ignite, so they must not be left in the open or in ordinary waste. A self-closing metal container limits oxygen and vapour, and the contents are disposed of as hazardous waste.

Question 16Occupational Safety, Health and Environment

Oxy-acetylene equipment is fitted with flashback arrestors at the regulator outlets. Which hazard do these devices control?

  1. A flame travelling back through the hose into the cylinder Correct answer.
  2. Acetylene accumulating in the bay from a leaking hose
  3. A sudden drop in gas pressure when the cutting nozzle blocks
  4. Overheating of the torch tip during continuous cutting

Explanation

A flashback occurs when a flame travels back through the torch and hose against the normal gas flow, and it can reach the regulator and cylinder. Flashback arrestors contain the flame and stop the pressure wave before it reaches the cylinder.

Question 17Hand Tools, Measuring and Marking Instruments

In auto body repair, which hammer has a wedge-shaped peen that concentrates force along a narrow line and is used for planishing a weld bead and stretching a local area of steel?

  1. Shrinking hammer
  2. Pick hammer
  3. Ball-peen hammer
  4. Straight-peen hammer Correct answer.

Explanation

The straight-peen hammer carries a wedge-shaped cross peen that stretches steel along one direction, which makes it the tool for planishing weld beads and stretching a local area. Its flat face is used for ordinary bumping, while the peen concentrates the blow on a narrow line.

Question 18Hand Tools, Measuring and Marking Instruments

A feeler gauge set is the correct hand tool for which of these auto body repair tasks?

  1. Measuring the dry film thickness of paint on a repaired panel
  2. Checking the tightening torque of a door hinge bolt
  3. Checking the hardness of a repaired panel
  4. Measuring the width of a panel gap between a door and its aperture Correct answer.

Explanation

Feeler gauge blades are ground to known thicknesses and are combined until they just fill a gap, so in body work they are used to measure and compare panel gaps and clearances. The resulting figure tells the technician whether a door, hood or fender sits within the manufacturer's gap tolerance.

Question 19Hand Tools, Measuring and Marking Instruments

A standard centre punch used to mark drill locations on a sheet metal panel is ground to which included point angle?

  1. 90 degrees Correct answer.
  2. 30 degrees
  3. 120 degrees
  4. 45 degrees

Explanation

A centre punch is ground to a 90 degree included angle so that the point sinks a generous conical dimple which guides the drill and stops it wandering. The sharper 60 degree point belongs to a prick punch, which is used only for marking out layout lines.

Question 20Hand Tools, Measuring and Marking Instruments

A vernier caliper has a main scale graduated in 1 mm and a vernier scale of 50 divisions. The main-scale zero sits just past the 12 mm mark and the 24th vernier division coincides with a main-scale line. What is the reading?

  1. 12.24 mm
  2. 12.96 mm
  3. 12.45 mm
  4. 12.48 mm Correct answer.

Explanation

Fifty vernier divisions give a least count of 1 divided by 50, which is 0.02 mm. The main scale contributes 12 mm and the coinciding 24th vernier line adds 24 multiplied by 0.02, that is 0.48 mm, so the reading is 12.48 mm.

Question 21Hand Tools, Measuring and Marking Instruments

A metric outside micrometer has a spindle pitch of 0.5 mm and 50 thimble divisions. The barrel shows the 7 mm mark plus one 0.5 mm graduation, and the thimble reads 28. What is the measured size?

  1. 7.53 mm
  2. 7.78 mm Correct answer.
  3. 8.28 mm
  4. 7.28 mm

Explanation

Each full turn of the thimble advances the spindle 0.5 mm and is divided into 50 parts, so one thimble division equals 0.01 mm. The barrel contributes 7.5 mm and the thimble adds 28 multiplied by 0.01, that is 0.28 mm, giving 7.78 mm in total.

Question 22Hand Tools, Measuring and Marking Instruments

During repair of a unitised body, a tram gauge is used to do which of the following?

  1. Measure the diameter of a drilled hole in a repair panel
  2. Check the valve clearance of a dismantled engine
  3. Measure the paint film thickness on a refinished panel
  4. Compare diagonal and point-to-point distances between underbody reference points Correct answer.

Explanation

A tram gauge is a long adjustable bar fitted with pointed or hooked legs, used to compare point-to-point and diagonal distances between datum points on the underbody. Unequal diagonals show that the body shell has been pushed out of square, so the gauge is the standard check for collision misalignment before and after pulling.

Question 23Hand Tools, Measuring and Marking Instruments

A technician has to trim a repair panel of 0.9 mm mild steel along a tight curve that bends to the left. Which hand tool is designed for this cut?

  1. Long-nose aviation snips
  2. Offset straight snips
  3. Left-cutting aviation snips Correct answer.
  4. Right-cutting aviation snips

Explanation

Aviation snips are made in left-cut, right-cut and straight patterns, and the direction refers to the way the cut curls as the tool moves forward. Left-cutting snips let the blades follow a tight curve to the left without the offcut curling up and jamming the blades, whereas right-cutting snips are used for curves that bend the other way.

Question 24Hand Tools, Measuring and Marking Instruments

A contour (profile) gauge is used in body repair for which purpose?

  1. Setting a door-to-aperture gap
  2. Checking the runout of a brake disc
  3. Measuring the depth of a dent in a panel
  4. Copying a curved profile for transfer to a new panel Correct answer.

Explanation

A contour gauge is made of many closely spaced sliding pins; when pressed against a shape the pins lock and reproduce the profile, which can then be traced onto a card or a replacement panel section. It is a copying tool rather than a measuring instrument and does not give a numerical gap or depth reading.

Question 25Hand Tools, Measuring and Marking Instruments

A vernier caliper has a main scale graduated in 1 mm, and 20 divisions on its vernier scale exactly coincide with 19 divisions of the main scale. What is the least count of this caliper?

  1. 0.50 mm
  2. 0.10 mm
  3. 0.02 mm
  4. 0.05 mm Correct answer.

Explanation

Least count equals the value of one main-scale division minus the value of one vernier division. One vernier division spans 19 divided by 20, that is 0.95 mm, so the least count is 1.00 minus 0.95, which equals 0.05 mm.

Question 26Hand Tools, Measuring and Marking Instruments

With its jaws fully closed, a vernier caliper reads a positive zero error of 0.06 mm because the vernier zero lies ahead of the main-scale zero. A component then measures 34.58 mm on the same instrument. What is the true dimension?

  1. 34.64 mm
  2. 34.55 mm
  3. 34.52 mm Correct answer.
  4. 34.61 mm

Explanation

When the jaws are closed the instrument should read zero, so an offset of three vernier divisions means a positive zero error of 3 multiplied by 0.02, that is 0.06 mm. Every reading is therefore too large by 0.06 mm, and the true size is 34.58 minus 0.06, which equals 34.52 mm.

Question 27Hand Tools, Measuring and Marking Instruments

A technician must cut a 1 mm thick mild steel repair panel using a hand hacksaw. Which blade pitch is most suitable for this cut?

  1. 24 teeth per inch
  2. 14 teeth per inch
  3. 32 teeth per inch Correct answer.
  4. 18 teeth per inch

Explanation

Thin sheet metal requires a fine-pitch blade so that at least two teeth remain in contact with the material throughout the stroke. A 32 TPI blade cuts 1 mm steel cleanly, while coarser blades tend to snag, chatter and tear the panel edge.

Question 28Hand Tools, Measuring and Marking Instruments

Which hand tool is used to quickly level and shape a layer of body filler before finish sanding?

  1. Ball-peen hammer
  2. Spring dividers
  3. Feeler gauge
  4. Body file Correct answer.

Explanation

A body file has a long, flat, coarse-toothed face that cuts through surplus filler rapidly and brings it down to the panel contour. Finish sanding then removes the file scratches.

Question 29Hand Tools, Measuring and Marking Instruments

A technician needs to measure the outside diameter of a round steel tube and then transfer that size to a steel rule. Which measuring instrument is designed for this task?

  1. Depth gauge
  2. Divider
  3. Inside caliper
  4. Outside caliper Correct answer.

Explanation

Outside calipers have legs that face inward and are set across the outside of the tube; the setting is then held against a steel rule. Inside calipers measure internal bores, depth gauges measure depth, and dividers are for marking arcs or transferring distances.

Question 30Hand Tools, Measuring and Marking Instruments

A technician must scribe a 40 mm radius arc on a 1.2 mm aluminium repair panel. Which marking tool is most appropriate?

  1. Spring dividers Correct answer.
  2. Contour gauge
  3. Centre punch
  4. Tram gauge

Explanation

Spring dividers have two sharpened legs and a setting screw; set the points to 40 mm, pivot on the centre mark and scribe the arc. A centre punch marks a point, a tram gauge is for large distances and alignment, and a contour gauge copies profiles.

Question 31Hand Tools, Measuring and Marking Instruments

A body file has become clogged with cured body filler dust and no longer cuts efficiently. Which action correctly restores its cutting action?

  1. Rub the file face with emery cloth until clean
  2. Wash the file in thinner and keep cutting
  3. Draw a file card along the tooth grooves Correct answer.
  4. Strike the file against a steel bench to shock it

Explanation

A file card is a stiff wire brush used to pull packed material out from between the teeth; draw it along the tooth grooves. Abrasives and impact damage the teeth, and solvent does not remove cured filler.

Question 32Hand Tools, Measuring and Marking Instruments

A 0–25 mm metric outside micrometer is checked with its jaws closed. The thimble zero is below the barrel datum line by 3 divisions, giving a zero error of −0.03 mm. When measuring a panel thickness, the micrometer reads 5.62 mm. What is the corrected thickness?

  1. 5.59 mm
  2. 5.65 mm Correct answer.
  3. 5.62 mm
  4. 5.68 mm

Explanation

A negative zero error means the micrometer reads 0.03 mm low, so the error must be subtracted algebraically: 5.62 − (−0.03) = 5.65 mm. Adding 0.03 would be the correction for a positive zero error.

Question 33Sheet Metal Work and Body Panel Fabrication

In hammer-and-dolly planishing of a low-crown dent, where should the dolly be held?

  1. Directly behind the panel, opposite the hammer face Correct answer.
  2. On the outside of the panel, beside the hammer
  3. At the edge of the panel, away from the dent
  4. Under the nearest body mount for support

Explanation

Planishing works by trapping the panel between the hammer face and the dolly so the metal is squeezed back to shape instead of being driven inward. The dolly must therefore sit on the back of the panel directly opposite the hammer blow, with light overlapping blows worked from the outside of the damage inward.

Question 34Sheet Metal Work and Body Panel Fabrication

Which material is the correct catalyst for a polyester body filler?

  1. A few drops of clean water
  2. The cream hardener supplied with the filler Correct answer.
  3. Cellulose thinner
  4. A two-part epoxy resin

Explanation

Polyester filler cures by a chemical reaction started by the organic peroxide hardener, usually MEKP in a cream carrier, that comes with the product. The ratio stated on the label must be followed: extra hardener shortens pot life and can leave a brittle, porous film, while too little leaves the filler tacky.

Question 35Sheet Metal Work and Body Panel Fabrication

On the standard sheet-metal gauge scale, a 22-gauge steel panel compared with an 18-gauge panel is:

  1. Thicker
  2. More resistant to corrosion
  3. Thinner Correct answer.
  4. The same thickness but harder

Explanation

Sheet gauge numbers run inversely to thickness: the higher the gauge number, the thinner the sheet. A 22-gauge panel is therefore thinner than an 18-gauge panel, which matters when setting welder amperage, choosing hammer force and selecting the right body filler grade.

Question 36Sheet Metal Work and Body Panel Fabrication

After heating a stretched area of steel to a dull red with an oxy-acetylene torch, which step completes a heat shrink?

  1. Hammer it hard while it is still red hot
  2. Let it air-cool slowly in still air
  3. Play compressed air on it from a distance
  4. Quench the hot spot with a wet sponge, then planish Correct answer.

Explanation

Rapid quenching contracts the hot, softened metal and takes up the excess stretch, so the spot is quenched with a wet sponge or rag while it is still hot. Light planishing afterwards smooths the surrounding area and blends the shrink into the panel contour.

Question 37Sheet Metal Work and Body Panel Fabrication

When MIG welding a butt joint in 0.8 mm body steel, which technique best limits heat distortion?

  1. Spaced stitch welds with cooling between passes Correct answer.
  2. One continuous pass at maximum amperage
  3. A fast continuous pass with high wire speed
  4. Preheating the whole panel to 250 degrees C first

Explanation

Thin sheet distorts because heat is concentrated in one place, so stitching spreads the heat along the joint and lets each tack cool before the next is placed. Continuous runs on 0.8 mm steel put far too much heat into the panel and cause buckling, oil-canning and a stretched weld seam.

Question 38Sheet Metal Work and Body Panel Fabrication

Before welding a replacement panel into position, the best way to confirm final alignment is to:

  1. Fit the panel with the doors removed so nothing can contact
  2. Apply filler to the gaps and sand them to final width
  3. Clamp or screw it in place and check gaps and door swing Correct answer.
  4. Tack the top edge first, then lever the lower gaps into place

Explanation

Panel gaps, door and hood operation and trim alignment must be set while the replacement part is still free to move. Temporary screws or clamps hold the panel in the correct position so the technician can check and adjust everything before welding locks the alignment in.

Question 39Sheet Metal Work and Body Panel Fabrication

Weld-through primer is applied to which surface during a plug-welded panel installation?

  1. The finished exterior, after the panel is painted
  2. The back of the wheel arch, after welding is complete
  3. Over the seam sealer once the welds have cooled
  4. The bare mating flanges, before clamping together Correct answer.

Explanation

Weld-through primer protects the flange faces that are pressed together and can never be painted later, while still allowing current to pass for a sound plug weld. It is applied as a thin coat to clean bare steel only, before the panels are clamped and welded.

Question 40Sheet Metal Work and Body Panel Fabrication

A replacement panel is being bonded with two-part structural adhesive instead of welding. The mating flanges should be:

  1. Coated with body filler to level the joint
  2. Left with the original e-coat and wiped with solvent
  3. Primed with etch primer and left wet when bonded
  4. Abraded, cleaned, and given the adhesive maker's primer Correct answer.

Explanation

Structural adhesives only develop full strength on a properly prepared surface: abraded bare metal, degreased, then coated with the primer specified by the adhesive manufacturer. Bonding over paint, filler or factory e-coat gives a weak joint that may fail under collision loads.

Question 41Sheet Metal Work and Body Panel Fabrication

On a wheeling machine, the amount of crown formed in a panel is mainly set by:

  1. The speed at which the panel is passed through
  2. The thickness of the upper wheel's rubber tyre
  3. The radius of the lower anvil wheel Correct answer.
  4. The grain of the aluminium sheet being formed

Explanation

A flatter, larger-radius anvil stretches the metal less across its width and produces a gentle crown, while a small-radius anvil concentrates the pressure and forms a tighter curve. Wheel pressure controls how much the metal is thinned and stretched rather than the radius of the crown itself.

Question 42Sheet Metal Work and Body Panel Fabrication

After a dent is pushed out, the panel oil-cans and snaps through under light finger pressure. The correct repair is to:

  1. Hammer the area on-dolly to raise the crown further
  2. Stretch the surrounding metal to match the bulge
  3. Shrink the stretched, over-crowned area back to shape Correct answer.
  4. Apply a thick skim of filler to stiffen the panel

Explanation

Oil-canning shows that the panel has been stretched and its crown is too high, leaving the metal unstable past a certain point. Heat shrinking or a shrinking hammer removes the excess surface area, restores the correct crown and returns the panel to a stable, springy shape.

Question 43Sheet Metal Work and Body Panel Fabrication

When roughing out a broad, shallow dent in a steel door skin, which hammer face is the best starting choice?

  1. A high-crown planishing face
  2. A serrated shrinking face
  3. A low-crown general-purpose face Correct answer.
  4. A sharp pick face

Explanation

A low-crown general-purpose face moves metal over a wide area without concentrating stress, so it suits broad, shallow damage. Pick faces are for sharp local damage, serrated faces are for shrinking, and high-crown planishing faces are used for final finishing.

Question 44Sheet Metal Work and Body Panel Fabrication

Which tool creates an offset step along a panel edge so a replacement panel can sit flush for a lap joint?

  1. A joggler Correct answer.
  2. An English wheel
  3. A shrinker
  4. A bead roller

Explanation

A joggler punches or flanges a step into the panel edge, producing an offset that lets the replacement panel sit flush for a lap joint. Bead rollers form ribs, shrinkers gather edges, and English wheels shape compound curves.

Question 45Sheet Metal Work and Body Panel Fabrication

What is the primary effect of running a panel edge through a shrinker?

  1. It gathers the edge and contracts the metal Correct answer.
  2. It rolls a wire edge into the panel
  3. It planishes welds and flattens high spots
  4. It stretches the edge and increases crown

Explanation

A shrinker uses jaws that gather the metal in small increments, contracting the edge and pulling the panel into shape. It is used to remove slack or excess metal along an edge, not to stretch or planish.

Question 46Sheet Metal Work and Body Panel Fabrication

Why is a replacement patch panel sometimes given a slight over-crown before it is welded into a flat area?

  1. To allow for the thickness of primer and paint
  2. To make the panel easier to trim with aviation snips
  3. To provide extra clearance for the dolly
  4. To compensate for shrinkage along the weld seam Correct answer.

Explanation

Weld heat causes the seam and surrounding metal to shrink, which pulls a flat patch tighter and can create a low area. A slight over-crown gives the panel room to flatten as the weld cools.

Question 47Sheet Metal Work and Body Panel Fabrication

What is the main effect of running a flat panel through a bead roller with a beading die set?

  1. It shrinks the panel edge to remove slack
  2. It punches a line of plug-weld holes
  3. It forms a stiffening rib Correct answer.
  4. It planishes weld seams flush

Explanation

A beading die set forms a raised rib or groove that adds stiffness to a flat panel and helps control oil-canning. It does not shrink edges, planish welds, or punch plug-weld holes.

Question 48Sheet Metal Work and Body Panel Fabrication

Which MIG wire and shielding gas combination is typical for welding 1.0 mm mild steel body panels?

  1. ER308L stainless wire with pure argon shielding
  2. ER4043 aluminum wire with pure argon shielding
  3. ER70S-6 with argon/CO2 gas Correct answer.
  4. ER5356 aluminum wire with helium shielding

Explanation

ER70S-6 is a common mild-steel MIG wire, and an argon/CO2 mixture provides stable arc characteristics and good bead shape on thin body steel. Stainless and aluminum wires require different base metals and shielding gases.

Question 49Sheet Metal Work and Body Panel Fabrication

A 90-degree flange in 1.2 mm mild steel springs back to 87 degrees after the ram is released. What is the correct compensation on the press brake?

  1. Overbend to approximately 93 degrees Correct answer.
  2. Reduce ram travel until the bend reads 87 degrees
  3. Increase the die opening without changing ram depth
  4. Bend to 90 degrees and correct the angle by planishing

Explanation

Springback is the elastic recovery of the bend after the load is released; here it is 3 degrees. The ram must overbend by that same amount, so a 93-degree bend is needed to leave a 90-degree flange.

Question 50Sheet Metal Work and Body Panel Fabrication

Why is alternating current with high-frequency arc stabilization normally used when TIG welding thin aluminum body panels?

  1. It prevents the filler wire from melting before the base metal
  2. It gives oxide cleaning and stable penetration Correct answer.
  3. It keeps the tungsten electrode from ever touching the workpiece
  4. It allows the weld to be made without any shielding gas

Explanation

On aluminum, the alternating current provides a cleaning action on one half-cycle and penetration on the other, while high frequency stabilizes the arc. This combination helps break up the oxide layer without excessive heat input.