When two strong surfaces are held apart by a firm structure, the result is far more rigid than the sum of the three constituent parts. This is the familiar principle upon which the manufacture of corrugated board is based. Unlike solid board, corrugated does not depend upon mere thickness for its Strength. The composite material is light and tough, as well as rigid.

Different duties are served by varying the weight of individual components and the profile of the fluting. Two basic sizes of used. C flute board gives the greater beam and compression strengths because its surfaces are more widely separated. In B flute board the contours are shallower and closer-knit. It offers strong resistance to crushing and at the same time helps to keep down freight and storage charges by reducing the bulk of a case. Where exceptional rigidity and strength are needed, C flute and B flute are combined to form BC flute, also called twin-flute or double-wall board.


The Corrugator is a combination of many individual machines brought together to make one very complicated, yet synchronized, piece of machinery which is used for the conversion of the paper into different types of board.

The different pieces of equipment which basically make up the Corrugator are as follows:-

  1. SINGLE FACER (one for B flute and one for C flute)








This section of the machine converts the reels of inner liner paper and fluting medium into single face fluted board.

It is fed from the reel stand on one side by the fluting medium and from the other by a liner. This liner is normally inner liner the outer liner is applied at the Double Backer stage.

The fluting medium is fed by way of a series of pre-heated rollers through a steamer pre-conditioning section to the first Corrugator roll, it is then passed between the first and second Corrugator rolls; this action cause a the paper to be nipped, and so form the corrugations. Before leaving the Corrugator main roll an application of starch glue is applied to the tips of the flutes, by the glue applicator roll. The fluting, still held in contact with the main Corrugator roll by line of vacuum nozzles, passes over the pressure roll where it meets the liner and so forms Single Face corrugated board. Older corrugators held the fluting medium by single piece fingers, this is why most modern corrugators, is described as having a "Fingerless single facer".

This single face board is then fed to the Double Backer by way of the bridge.

This action is exactly the same for both B and C flute, only the machine setting and tolerances vary from one to the other. It should also be mentioned that the lower Corrugator roll remains fixed and the upper Corrugator roll, the glue applicator roll and the pressure roll, can all be adjusted to ensure that even corrugation, glue application and caliper takes place.

Other refinements are also incorporated in the machine to ensure that these factors are kept constant, such as liner tensioning and board moisture control.


This part of the machine prepares the single face board and the liner (outer) before double face board is formed.

The single face board comes from the bridge through a heater dryer unit to the glue machine where application is identical to that at the Single Facer. It then passes from the applicator to meet the liner, which has been fed from the reel stand through a pre-conditioner just as it enters the heating section.


This section is a series of 'Hot Plates' called Steam Chests, which are kept at a temperature around 340 - 360 degrees. The double faced board passes over the top of these chests and the effect is to dry the board out and in turn this dries the glue to give good adhesion of liners to fluting medium. The board is kept in contact with the plates by a continuous belt, and the pressure applied by the belt is kept constant by idler rolls spaced at even intervals over the length of the Heating section.


A continuous belt takes the position of the steam chests and the board is allowed to cool as it continues towards duplex unit for and scoring.


The Slitting and creasing units are a positioned series of shafts. The they are usually separated into slitting and creasing shafts. are two slitting shafts and three creasing shafts. As the board enters the units for creasing, and then is slit to the correct first-way size. The bends and slit blades on these shafts can be positioned anywhere on the shafts within the limitations of the mounting bosses, (which is the width of that boss). Setting of the slitting and scoring units is often computer controlled. The shafts can be raised and lowered as required, to enable most standard first way crease to crease sizes to be manufactured on a Corrugator with multiple shafts. Creases are of usually of the 3 point reverse or the 2 point Sauer type.


This is a very complicated cutting machine, which cuts the board into lengths as required.

The setting up of the chop size automatic and the board length is governed by a complicated Gear assembly. The speed of the machine and the position of the belts on the gear wheels gives the resultant board length. The Chop unit can be of the single  or multiple type. The a single knife design has gained in popularity over recent years. This means that only one job can be run at a time on this machine. Corrugators that have multiple chop knives, can run more than one job, in a particular grade,  at one time. Both systems have their plus and minus points.


This is a series of belts which control the flow of finished boards to the take-off section. On exiting the chop section the pieces of board, which have now been cut to their correct board size and had any first way bends put in, are separated and then shingled as they start to go up the inclined belts. At the top of the belts the boards reach the down stacker. The number of boards in the bundles at the take-off points is regulated by gates which work automatically. When the set number of boards is reached those still on the conveyor are held by the gates while the completed stack is lowered to the bottom conveyor. The stacks pass down a final conveyor system and are then automatically palletized. A forklift then places the palletized board into a holding area prior to conversion.


STARCH GLUE, This is made by the Starch Plant Operator in the Starch plant, adjacent to the Corrugator.

Basically the contents of a normal mix is:

550 Gals. of WATER
9 cwts. STARCH POWDER (normally maize)
33 lbs. BORAX

Single Facer - 35-40 secs
Double Backer - 60-70 sees