NABTEB Light Vehicle Body Repair flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

PPE for 2K clearcoat

Air-fed breathing apparatus covering the full face, plus nitrile gloves and coveralls. Isocyanate hardeners can cause permanent occupational asthma, so a dust mask or a charcoal half-mask is not adequate protection.

Compressed air blow-gun limit

Restrict blow-gun pressure to about 2 bar (30 psi) with a dead-man nozzle and eye protection. Workshop line pressure used on skin can force air into tissue and damage hearing.

Shrinking hammer

A body hammer with a crowned or serrated face that gathers metal together. It is used to shrink a stretched, oil-canned area and is followed by planishing to smooth the surface.

Dolly heel and toe

The heel is the curved working face used for general off-dolly work; the toe is the narrow end for tight returns and flanges. The dolly acts as a reaction mass behind the panel.

Boron steel repair rule

Boron and martensitic steels in pillars and reinforcements can exceed 1,500 MPa and are normally classified as not repairable. They must be replaced at the manufacturer's sectioning points, not heated or straightened.

Galvanic corrosion

Corrosion caused when two dissimilar metals, such as steel and aluminium, are joined in the presence of an electrolyte. The less noble metal corrodes; isolate the joint with sealant or coated fasteners.

Torque-to-yield bolt

A bolt tightened past its elastic limit to a torque plus a specified angle, for example 40 Nm plus 90 degrees. It deforms permanently and must be replaced, never reused, on safety-critical joints.

Resistance spot weld nugget

The fused zone formed at the faying surface when current passes through the electrodes. Nugget diameter is typically 4 to 6 mm on 0.8 mm sheet and is checked by a chisel or peel test.

Spot-weld drill sequence

Centre-punch the weld, drill a 3 mm pilot, then cut with an 8 mm spot-weld cutter. Do not drill through both layers; remove the residual nugget with a belt sander before fitting the new panel.

Door gap and flush

Typical door gaps are 4 to 6 mm with flushness within plus or minus 1 mm. Record the gaps before strip-down as a baseline and adjust at hinges, shims and slotted mountings.

Off-dolly panel beating

The dolly is held beside rather than behind the hammer blow, so the panel is pushed back into shape without thinning. It is the primary method for removing shallow dents.

Oil-can effect

A stretched area that drums in and out when pressed, caused by metal worked beyond its elastic limit. Hammering alone cannot correct it; the area must be shrunk.

Heat shrinking and quenching

Heat a small spot to dull red, about 600 to 700 degrees Celsius on mild steel, then quench with a damp cloth. The rapid contraction of the hot spot removes stretch; repeat in small steps.

Heat limits on AHSS

Most manufacturers prohibit heating advanced high-strength steels above about 200 degrees Celsius, and some prohibit heat entirely. Boron and martensitic steels must not be heated at all.

MIG brazing

A joining process using copper-silicon wire that melts the filler but not the parent metal. It gives lower heat input than steel welding and protects zinc coatings, but it is not a fusion weld.

MIG settings for body sheet

With 0.8 mm wire on body sheet, typical settings are 60 to 90 amps and 15 to 18 volts, with shielding gas at 10 to 15 litres per minute. Wire feed sets current and voltage sets arc length.

Polyester filler mixing ratio

Measure hardener at about 2 percent by weight of the filler and mix to a uniform colour. Excess hardener causes cracking and shrinkage; too little leaves a tacky, uncured surface.

Body filler maximum thickness

Build filler in thin coats to a maximum of about 3 to 5 mm. Thicker areas should be repaired by panel replacement or fibreglass bridging, because thick filler cracks and shrinks.

Guide coat

A light contrasting dusting applied over primer or filler. Sanding cuts the guide coat away from high spots first, revealing low areas and scratches so the surface can be levelled.

Etch primer use

A thin, acid-containing primer applied to bare steel and aluminium for adhesion and corrosion protection. It is applied in thin coats and is not sanded before the next coat.

HVLP spray gun distance

Hold an HVLP gun 150 to 200 mm from the surface, perpendicular, with a constant speed and 50 percent overlap. Trigger before and after the panel edge to avoid a heavy build at the ends.

Fisheye paint defect

Small circular craters in the paint film caused by silicone or oil contamination on the panel or in the air line. The panel must be cleaned and the source of contamination removed before recoating.

Three-stage pearl colour

A ground coat, a pearl or tint mid-coat, and a clearcoat. Matching requires the correct number of mid-coats, checked against a spray-out card in natural daylight.

Spray-out card

A test card sprayed with the mixed colour and allowed to dry. It is compared with the vehicle in natural daylight, because artificial light changes the apparent hue of metallic and pearl colours.

Windscreen adhesive bead

A polyurethane bead typically 8 to 12 mm wide and 6 to 10 mm high applied to the primed aperture. The manufacturer specifies the drive-away time, which must not be shortened.

ADAS recalibration after glazing

A camera or sensor mounted behind the windscreen must be recalibrated after glass replacement. The vehicle must be on a level surface with correct tyre pressures and the specified load.

Direct and indirect damage

Direct damage occurs at the impact point; indirect damage is transferred through the structure; inertia damage is caused by components continuing to move after the impact. All three must be assessed.

Datum and control points

The datum is a horizontal reference plane; control points are specified holes and features on the underbody. Measurements are taken to the centre line and the datum and compared with the manufacturer's data sheet.

Structural sectioning rule

Cut only at the manufacturer's designated sectioning points, use the specified joint type, and restore the original weld count and corrosion protection. Unauthorised cuts weaken the occupant cell.

Seam sealer

A paintable compound applied to panel joints after welding or bonding to keep water out. It must be applied over primed metal and overpainted to restore the original corrosion protection.

Tram gauge limitation

A tram gauge measures point-to-point distance only. It cannot confirm three-dimensional alignment to the datum, so structural repairs need a bench or computer measuring system.

Panel alignment sequence

Align the largest fixed panel first, then the door to the aperture, then the front wing to the door and bonnet. Adjust gaps at hinges, shims and slotted mountings, checking flushness throughout.