The grooving machine of the series TRI-NU treats the surface of metal strips. It is employed when deep and/or wide grooves have to be drawn in. The machine works with three tools. The depth and the width as well as the number of grooves are variable, because the tools are horizontally and vertically adjustable. Due to its compact construction the grooving machine can easily be integrated into existing lines. The machine can be combined with modules of strip edge trimming so that the surface and the edge can be treated simultaneously.