Separation unit and a dispenser comprising a separation unit

A method of refilling a dispenser with a pre-folded refill bundle in the form of a stack of a Z-folded web of paper having a plurality of longitudinally spaced preformed lines of weakness, the method comprising:

• providing or obtaining a dispenser having a separation unit, wherein the separation unit comprises:
• a first device having an axis extending in a width directions and a web width extending in said width direction, and
• a second device having an axis extending parallel with said axis of said first device, said second device being positioned at a distance from said first device, and a web width extending in said width direction, said distance extending in a direction perpendicular to said width direction,
• wherein each of said first and said second devices is provided with a plurality of protrusion elements being spaced along said axes and protruding perpendicularly from said axes,
• wherein each of said protrusion elements has a maximum width in said width direction, a maximum extension from said axes, an inner portion adjacent to said axes, and an outer portion remote from said axes,
• wherein said outer portions of said protrusion elements on said first device are arranged in a staggered relationship with said outer portions of said protrusion elements on said second device, and
• wherein said outer portions of said protrusion elements on said first device are partially overlapping with said outer portions of said protrusion elements on said second device with a overlap length, thus forming an undulating passage for a web material between said devices,
• wherein each protrusion element has a maximum width along the width direction within the overlap length, and the sum of said maximum widths within the overlap length of all protrusion elements on one of said devices is between 5-30% of said web width of that device,
• wherein the separation unit is configured to create a pinch force on the web material, wherein the separation of the web material along a preformed line of weakness comprises passage through the separation unit and the pinch force, and wherein the separation unit is configured to separate the web of paper along a preformed line of weakness with the pinch force;
• inserting the refill bundle of the Z-folded web of paper through a bottom section of the dispenser comprising a plurality of walls defining a reservoir for holding one or more pre-folded bundles of Z-folded web, and a dispensing opening, the dispenser extending vertically along a longitudinal dimension and horizontally along a width dimension;
• and
• connecting the refill bundle of the Z-folded web of paper to an existing bundle of a Z- folded web of paper already in the reservoir, and
• wherein said Z-folded web of paper comprises at least a first web divided into sheet products defined between longitudinally separated lines of weakness extending across the first web;
• and at least a second web divided into sheet products defined between longitudinally separated lines of weakness extending across the second web;
• wherein the webs are interfolded so that the lines of weakness of the first web are offset from the lines of weakness of the second web in a longitudinal direction of the first web,
• wherein a sheet product from only one web is configured to be dispensed at a time.