Technology

• shaped packaging – made by punching methods using punching dies
• imprint – flexo methods for corrugated cardboards, offset – for solid cardboards, laminated packaging
• laminated packaging – this technology combines the advantages of offset printing and the strength of corrugated board – E, B, C, BC, BE; laminating is possible for 2-, 3-, 5-layer cardboard
• slotted boxes – of corrugated cardboard, flute E, B, C, BC, BE – colour: grey, white, marble – imprint: flexographic
• box cut-outs for folding according to any FEFCO configuration or standards, e.g.
  – foiling trays open from the top – pizza boxes – for industry (power tools, machines, household chemicals, etc.) – paper boxes – shoe boxes
• punched glued boxes – displays with perforations – boxes with cross-shaped bottom, glued, open automatically – boxes with cardboard or plastic handles – boxes with retractable handles – boxes to be hung – stands, advertising racks
  box fitting of any dimensions, shapes – grating – spacers – inserts.

Corrugated cardboard consists of several sheets of paper..

Straight outer (smooth) and inner corrugated (flute) sheets. In the case of two-layer cardboard, there is one smooth sheet and the other corrugated one. The diagram presents structure of corrugated cardboard sheets:

1. two-layer cardboard (most often found on rolls)
2. three-layer cardboard
3. five-layer cardboard
4. seven-layer cardboard
5. four-layer cardboard

(The term of a two-, three-, etc. layer comes from the number of layers of paper, e.g. three layers are two sheets of outer paper and one inner called flute – three sheets of paper together)

a. flute height
b. space between the flute tops

Known flute types are:

• E flute (micro-flute) flute with height from 1.1 mm to 1.7 mm. Cardboard with this flute is rather aesthetic and is suitable for small packaging and not containing heavy goods. Often used for packing of seasoning, jellies, cappuccino coffee.
• B flute flute with height from 2.5 mm to 3.0 mm
• C flute flute with height from 3.0 mm to 3.7 mm
• five-layer cardboards are combinations of the above types of flutes, usually it is BC flute (B+C), EB, EC flute combinations are frequent as well.

Less common are:

• A flute – flute with height from 3.6 to 4.5 mm, withdrawn and basically less common
• N flute – flute with height about 0.6 mm
• X flute (1e diagram) – this is a four-layer cardboard with two outer sheets and two corrugated sheets of which the tops meet with each other

Cardboard with high flute has better elastic properties and greater stiffness and packaging made of it usually protects the goods better. On the other hand, low-flute cardboard has much better flat crush resistance (FCT) and is therefore more resistant to impact, puncture and is better suited for printing.

To produce corrugated cardboard various types of paper are used which determine the quality and strength of the cardboard. Basic types of paper are:

• recycled paper
• testliner
• kraftliner.

The second significant factor affecting the quality of cardboard is basis weight of the paper used. Depending on the producers, the basis weight of cardboard (the sum of the basis weight of paper constituting the individual layers of paper) with or without glue (glue connecting the flute with external papers) is given. Basis weight and type of paper used to produce corrugated cardboard determine their quality and strength.

Cardboard and packaging strength can be measured in many ways of which the most common are:

FCT – flat crush resistance – measured in N – determines strength put on a sheet to brake the flutes. Sheet of cardboard laid flat in the press.

ECT – column (verticla) crush resistance – measured in N – determines strength put on a sheet to brake the sheet. Sheet of cardboard laid vertically in the press.

BCT – box pressing resistance – measured in N – the test consists of pressing a box between two parallel boards until the side walls of the box brakes.