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Rigid boxes, gift boxes and hardcover book covers are made from thick, stiff board. Folded as is, the board cracks or the fold comes out rounded and imprecise. This is where a grooving machine is used.

What grooving is

Grooving is the process of cutting a V-shaped groove into the part of the board that will be folded. Some of the board at the fold is removed, so the two sides of the groove meet tightly when folded and form a sharp angle. This differs from creasing, which only presses a line into paper.

What you set on a grooving machine

  • Groove position — the distance of the groove from the board edge sets the box size.
  • Groove angle — the fold angle follows the groove angle, for example 90° for a square box corner.
  • Groove thickness — matched to the board thickness so the material left at the fold stays strong.
  • Groove length — must cover the longest side of the box you are making.

Example: the KX-800 Grooving Machine

The KX-800 sets groove position automatically over 20–500 mm, with 90°, 120° and 145° angle options. Groove length is 0–800 mm, groove thickness 1–5 mm, and the machine also supports paper slotting. It weighs 120 kg and measures 105 × 100 × 105 cm.

A short rigid box workflow

  • Cut the board to box size with a paper cutting machine.
  • Groove the fold lines with the grooving machine.
  • Wrap the board in printed paper, then fold and glue the corners.

Common grooving mistakes

  • A groove that is too deep leaves a thin layer of board at the fold, which tears easily.
  • A groove that is too shallow keeps the fold from closing tightly and rounds the box corner.
  • Not testing on scrap board. Board thickness can differ between batches, so test before running the whole order.

Frequently asked questions

Which groove angles are available?

The KX-800 offers three angles: 90°, 120° and 145°.

What is the maximum groove length?

Groove length is 0–800 mm, which covers fairly long box sides.

Will the KX-800 fit in a small workshop?

It measures 105 × 100 × 105 cm and weighs 120 kg. Prepare enough space and a sturdy floor.

Taking rigid box or hardcover orders? Browse our grooving machines or contact Lexia Machinery in Medan.

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