ILL: The lines made on corrugated cardboard sheets in the corrugating machine, slotters, or die-cutting blades to allow folding. In printing, this is called “pilyaj,” while corrugated cardboard manufacturers refer to it as a rill.

SHEET (SAFIHA): Corrugated cardboard sheets cut to desired dimensions on a corrugating machine. The term “safiha” is a traditional industry term.

OVERLAP (BINDING): The edge of a box where the closing flaps meet in the center and overlap to the desired size.

FLAP : The extension flap corresponding to the length dimension of the box.

COATING: The process of covering the corrugated cardboard surface with various materials to increase resistance to water, moisture, and oil. Traditionally, wax was used; today, water-based products are preferred to allow paper recycling. Applied in the corrugating machine.

FLUTE: The wave-like shape seen in a cross-section perpendicular to the corrugations.

FLUTE PITCH : The distance between adhesion points of the flute in single-wall or corrugated cardboard.

FLUTE HEIGHT : The height between the top and bottom arches of the fluted paper.

NARROW FACE : The face of the box formed by width and height.

GLUING FLAP : A narrow strip (25–40 mm wide, box height long) joining the narrow and wide faces of a corrugated cardboard sheet to form a prism.

IMPREGNATION (EMPRENYE): The process of impregnating fluting paper with paraffin or other materials in the corrugating machine to improve durability, moisture resistance, and stacking strength.

WIDTH FLAP: The extension flap corresponding to the width of the box.

ZIPPER KNIFE : Paired knives used in corrugated cardboard boxes to facilitate opening. Used in die-cut production.

WIDE FACE : The face of the box formed by length and height.

VENT HOLE : Holes, usually round, cut with special dies in corrugated boxes to allow product ventilation.

EDGE TRIM : The piece cut from the edge of the sheet passing through the slotter to ensure dimensional accuracy.

FLAP TRIM : The piece cut from the top and bottom of the gluing flap.

FLUTE DIRECTION : Represented by an internal triangle according to FEFCO. Perpendicular to machine direction in corrugators; parallel to production direction in box-making machines.

CORRUGATED RILL : Rills applied in the corrugating machine to allow folding of box flaps. Always perpendicular to flutes.

PERFORATION: Partial cuts along a line to allow folding of corrugated cardboard sheets in both directions (inward and outward). Used in die-cut production.

PREPRINTING: Printing on liner paper as a roll before corrugating so that corrugated sheets come out printed.

SKIP FEED: When the sheet length exceeds the slotter cylinder circumference, the sheet is fed to the machine for two cylinder rotations while skipping one pass.

SLOT TRIM : The scrap produced from the slot opening.

SLOTTER RILL : Rills applied in the slotter to form box side faces. Parallel to flutes.

SLOT : Cuts made after slotter rills to form box flaps.

TEAR TAPE: Polypropylene tear tape (4–6 mm wide) applied perpendicular to flutes at specific points on the corrugated sheet to facilitate box opening.

HANDLE : Holes, usually 30×90 mm, on narrow faces of boxes to facilitate carrying. Can be full or half cuts made with special dies.

UPS-OPS-TWIN FLUTE-DUAL ARCH: A technique where two low-grammage papers are glued together and fluted to replace a single fluting sheet, improving strength and stacking performance.

EXTENDED GLUING FLAP: In glued boxes, the gluing flap is extended (about 40 mm) over the corrugated rill to prevent flap opening.