Metal Fabrication (Craft Apprenticeship Programme)
Metal Fabrication is the SOLAS craft apprenticeship trade covering the manufacture, assembly and repair of steel and sheet-metal components. The examination tests your ability to read engineering drawings, mark out and cut material, form and join components, inspect finished work, and apply safe working practices in an off-the-job Phase 2 or Phase 6 training setting. It rewards decisions you can justify from the drawing, the material specification and the workshop procedure-not guessed dimensions.
Core rules and concepts
- Work to the drawing: identify views, datum faces, dimensions, tolerances, weld symbols and surface finish. Never scale a drawing; use the stated dimension.
- Mark out from a common datum, allow for material thickness, kerf and bend allowance/deduction, and check squareness before cutting.
- For sheet-metal bends, flat length depends on inside radius (R), thickness (T), bend angle (A) and K-factor: BA = (π/180)(R + K×T)A. Use the agreed K-factor for the material and tooling.
- Joining: match process and consumable to material; prepare edges; control fit-up, current, travel speed and distortion.
- Inspection: check dimensions, squareness, weld size/profile and surface defects before sign-off; record results.
Worked example
A 90° bend in 2 mm mild steel has inside radius 3 mm and K = 0.5. Legs are 50 mm outside dimensions. BA = (π/180)(3 + 0.5×2)(90) = 0.017453×4×90 = 6.28 mm. For a 90° bend, setback = R + T = 5 mm, so bend deduction = 2×5 − 6.28 = 3.72 mm. Flat length = 50 + 50 − 3.72 = 96.28 mm. Cutting 100 mm would leave the part oversize.
Traps that cost marks
- Using outside leg lengths as flat length and ignoring bend deduction.
- Applying the wrong K-factor or mixing radius and diameter.
- Misreading arrow-side versus other-side weld symbols.
- Cutting before checking datum, squareness and kerf allowance.
- Controlling distortion only after welding instead of using tacking and balanced sequence.