Cutting optimisation and how to keep scrap below 3 %

Two different problems

Sections and bars are a one-dimensional problem: combine required lengths into stock bars (6 m, 12 m) with the least offcut. Plates are a two-dimensional nesting problem: place part outlines on sheets with the least waste, respecting the kerf, edge trim and the minimum gap between parts.

How scrap is measured

The levers

• True contours: nest the real shape of each part (with holes and copes), not its bounding rectangle.
• Pairing: rotate tapered or triangular parts by 180° and nest them in pairs.
• Stock sizes: choose sheet widths and lengths per thickness; order sheets cut to length when a full sheet is wasteful.
• Slit strips: cut long narrow flanges from strips slit along the sheet.
• Remnants: reuse remnants from stock first; return remnants above a minimum size (e.g. 300 × 300 mm plate, 1 m bar).
• Splices: allow at most one splice per long part, with the position approved by the designer.
• Buy to length: order hollow sections and pipes in the exact lengths where the supplier allows it.

Machine data

The nested layout is sent to the cutting machine as DXF. Cutting sequence, lead-ins and kerf compensation depend on the thickness and the machine, and are set in the CAM software.