The corrugator machine

The main parts of a corrugator are the splicer and reelstand:

These are the machines which feed the paper rolls into the corrugator and enable rolls to be changed without interrupting the production of corrugated board.

The single facer:

This machine transforms the paper into a series of connected arches called « flutes » thanks to the corrugating rolls that are large cylinders with a corrugated profile. If the flute profile has to be changed, then the corrugating rolls need to be changed.

The double backer:

It glues the outer liner to the fluting to obtain single, double or triple wallboard. The single face web is pre heated, starch is applied to the tips of the flutes. The outer liner is then bonded to the single face web to form corrugated board. It is a complex operation that requires great expertise in the pre-heating, moisture control and gluing processes.

The bridge:

This enables the Double Backer to run at different speeds from the Single Facer especially when reel or order changes take place. This is achieved by the single face web forming festoons that are controlled at the Single Facer station.

Bridge festoons

The glue unit and double backer:

Here, the single face web is prepared for glueing to the outer liner.

It is roughly the same process as the single facer unit with some variations of the pre-heating and gluing processes.

The hot plate section:

It is at this stage that the single face web is combined with the outer liner. The heating section ensures that the bond is strong by gelling the glue and removing moisture.

The rotary shear:

After the board emerges from the Double Backer it passes under a rotary shear that cuts across the whole width of the web. This is used to chop out damaged lengths of board or to effect a change over from one grade of board to another.

The slitter / scorer:

This operation slits and scores the board in the machine direction, with the scoring which determines the style of the finished box.

The cut-off knives:

These cut the board to the exact required lengths to obtain the corrugated sheet used in the making of corrugated packaging.

The stacker:

Finally, corrugated sheets are automatically stacked. Then they are moved directly to the conversion machine or sent to a converting plant.

2/ The Conversion process: the line convertor

This is the final stage of the process that consists in printing and then slotting, folding and gluing the corrugated board to manufacture a corrugated container.

Different operations are carried out according to the customer’s specification and according to the type of packaging.

The three main categories are the "regular slotted case", the flat bed "die-cut" container and the rotary "die-cut" container. Die-cutting concerns packaging which requires very precise cutting and which can have a complex design.

The converting process varies according to the type of packaging:

Whatever the type of packaging, printing on corrugated sheets is always possible.

The flexographic print process is commonly used for printing on corrugated.

This process uses the relief printing technique and is characterised by:

Printing can be done « in-line » or « off-line ».

The regular slotted cases (RSC):

Most of them are produced with an in-line flexographic Printer/ Slotter Folder Gluer which, in one operation, prints, cuts, folds and glues the blank into its final shape.

The packaging is then palletised and ready to be shipped flat to the customer.

The die-cut packaging:

Rotary Die-cutting

The die-cut containers are manufactured on a die-cutter that cuts and creases the board. It is usually reserved for a more sophisticated pack style.

This process requires a « form » that can be mounted around a cylinder, in which case the machine is called a rotary die-cutter, the other variant is called a flatbed die-cutter. As indicated by its name its form is flat.

Once the converting process is over, the corrugated packaging is put on a pallet and can be delivered to the customer.