What is CNC V-grooving?

V-grooving is a machining operation, not a forming one. A cutter runs along the intended bend line on the inside face of the sheet and removes a V-shaped channel, leaving a controlled web of material at the bottom of the groove. Only after that does the sheet go to the press brake.

A conventional bend wraps the sheet around a punch. The external corner can never be tighter than the tooling and the material allow, so it arrives with a visible radius — larger as the sheet gets thicker. With most of the material already removed, the sheet folds into the groove rather than around a radius, and the external corner closes to something that reads as a machined arris.

The visible face is not dragged and stretched over a tool radius, so it stays flatter and shows less distortion — which matters enormously on mirror and hairline finishes. Mitres and returns close tighter, leaving less to fill and grind before finishing. And because the groove is machined to a programme, the result repeats across a production run.

An extra operation, and a thinner section at the bend. The remaining web carries the corner, so a V-grooved profile is not the right answer where the corner is structural or will take impact. It also changes the developed length — bend allowances calculated for a plain bend will produce a short part.

Where the corner is visible and close: profiles at eye level, glass housing, lift cladding, reception and bar fronts, ceiling baffles. Where the section is concealed, high above the sightline, or structural, a conventional bend is the sensible and cheaper choice.