NABTEB Vehicle Body Building flashcards

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

Hierarchy of control

Ranking of hazard controls from most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment as the last defence.

Isocyanate hardener hazard

The curing agent in 2K paints can cause occupational asthma; sensitisation may follow a single overexposure, so supplied-air respiratory protection and health surveillance are required.

Spray booth face velocity

Air speed across an open booth face, typically at least 0.5 m/s (about 100 ft/min), which keeps solvent vapour and overspray from escaping into the workshop.

Flash point

The lowest temperature at which a liquid gives off enough vapour to ignite near an ignition source; below 23 °C the product is classed as highly flammable.

Dolly types

Heel dolly for general panel work, toe dolly for tight flanges, and curved dollies matched to panel curvature to avoid marking the surface during hammering.

Body hammer faces

Flat face for planishing, crowned face for stretching metal, and cross-peen for shrinking and working into corners during panel beating.

Torque wrench calibration

Checking the wrench against a known reference at least annually; impact wrenches must never be used to tighten torque-critical fasteners.

HVLP gun inlet pressure

Pressure measured at the gun inlet with the trigger pulled, typically 2–3 bar for gravity-feed HVLP, which gives high transfer efficiency and less overspray.

Boron steel repair limit

Press-hardened boron steel at about 1500 MPa must not be heated for straightening; heat destroys the martensitic structure and the crash performance.

Grade 8.8 bolt meaning

Tensile strength 800 MPa and yield strength 0.8 × 800 = 640 MPa; grade 10.9 gives 1000 MPa tensile and 900 MPa yield.

Galvanic corrosion prevention

Isolate aluminium panels from steel fasteners using coated or stainless fasteners and sealant barriers, because the dissimilar metals form a corrosion cell in moisture.

Blind pop rivet use

A rivet set from one side for non-structural panels; the hole diameter matches the rivet shank closely, and structural joints need monobolt or structural rivets.

Monocoque load path

Load is carried through sills, floor, A/B/C pillars and roof; cutting a sill or pillar removes structural strength and requires a sectioned repair.

Crumple zone purpose

Front and rear body sections designed to deform and absorb impact energy, while the passenger safety cell of pillars, sills and floor cross-members stays rigid.

Panel gap and flush target

Typical target of 4–6 mm gap and about ±1 mm flush between adjacent panels, checked with a gap gauge before final tightening of fasteners.

Frame diamond damage

A parallelogram distortion in plan view, detected by comparing diagonals between corresponding cross-member points; unequal diagonals indicate sway or diamond.

Spot weld nugget diameter

Target nugget diameter is 4√t mm for sheet thickness t; for 0.8 mm sheet this is about 3.6 mm minimum on a 12–16 mm flange.

Sectioning cut point rule

A high-strength rail may be sectioned only at the manufacturer's defined cut points, usually away from the crumple zone and reinforcement, with a backing insert.

Bend allowance formula

BA = θ × (π/180) × (R + K × t), where θ is bend angle in degrees, R inside radius, t thickness, and K the K-factor.

Minimum bend radius

About 1 × t for mild steel and 1.5–2 × t for aluminium alloys; bending tighter than this cracks the outer surface of the sheet.

Sheet metal gauge rule

Gauge numbering is inverse: a higher gauge number means thinner sheet; 20 gauge mild steel is about 0.9–1.0 mm.

Heat shrinking technique

Heat a small spot of about 5–10 mm to cherry red, then quench with a damp rag to lock in contraction and gather the stretched metal.

English wheel function

Upper and lower anvil wheels shape sheet metal; more pressure with closer anvils stretches and crowns the panel, while light pressure smooths the surface.

Springback compensation

After forming, metal springs back by an amount proportional to yield strength and inversely to thickness; over-bend by the measured springback.

MIG settings for thin steel

Use 0.6–0.8 mm wire, Ar/CO₂ or CO₂ shielding gas, and about 30–60 A for 0.8 mm sheet in short-circuit transfer only.

MIG brazing temperature

CuSi3 bronze filler works at about 950–1000 °C, below the steel melting point, so distortion is lower and it suits galvanised or high-strength steel joints.

Plug weld procedure

A rosette weld made through a punched hole of 6–8 mm, used to replace factory spot welds where access for a spot welder is limited.

Off-dolly hammering

The dolly is held under the low area while the surrounding high metal is hammered down onto it, lifting the low spot back to shape.

Oil-canning cause

A panel that pops between two stable shapes because the crown has been flattened without shrinking; the repair is to restore the crown by shrinking.

Direct hammering effect

Hammering directly on the dolly compresses and stretches the metal between hammer and dolly, flattening a crown rather than raising a low spot.

Pull direction rule

The pull must oppose the original impact direction; pulling the wrong way folds the metal further and work-hardens it, making correction harder.

Orange peel cause

A rough, textured paint finish caused by too little solvent, too high a viscosity, too fast a thinner, or too great a spray gun distance.

Feather edging

Sanding the paint step down so the repair blends smoothly, working through progressively finer grits such as 80, 180 then 320–400.

Vernier caliper reading

Read the main scale at the vernier zero, then add the vernier division that aligns; typical resolution is 0.02 mm.

First-angle projection

A drawing convention where the view from the front is placed below the front view; check the projection symbol before reading the drawing.