How Corrugated Board Is Made: Step-by-Step Process
Corrugated board looks simple, but making it consistently needs several machines working together. This guide walks through how corrugated board is made, from the paper reel to the stacked sheet, and explains the job of each stage.
What corrugated board is
Corrugated board is made of flat paper layers called liners bonded to a wavy layer called the fluting medium. The wave shape (the flute) creates air channels that give the board its stiffness and cushioning, which is why it protects goods so well.
Step 1: Loading the paper reels
Paper reels are mounted on reel loading stands. These hold each roll and feed paper smoothly with steady tension. Stands can be manual, hydraulic or shaftless depending on reel weight and how fast you need to change reels. See our guide to reel loading stands.
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The paper passes over heated drums. Preheating softens the paper fibres and brings moisture to the right level, so the fluting medium can be shaped without cracking and the glue bonds well.
Step 3: Forming the flute on the single facer
The fluting medium goes between two heated, grooved rollers that press the wave pattern into it. A glue applicator then puts starch adhesive on the flute tips and the first liner is pressed on. The result is single face board. Read more in our single facer machine guide.
Step 4: Bonding the second liner
For 3 ply board, a second liner is glued to the other side of the fluting. For 5 ply or 7 ply board, extra layers of flute and liner are added in turn. Heat and pressure cure the glue as the board travels forward.
Step 5: Drying, cooling and cutting
The board passes over heating plates and under belts that hold it flat while the adhesive sets. It is then slit to width and cut into sheets by a cutting machine, such as a rotary sheet cutting machine, and stacked.
After the board: converting into boxes
Sheets then go through printing, slotting, creasing, die cutting and stitching or gluing to become finished boxes. For the full list of machines, see our corrugated plant machinery guide.
Frequently asked questions
What is the difference between single face and 3 ply board?
Single face board has one liner glued to the fluting. 3 ply board has liners on both sides of the fluting.
Why is the paper heated?
Heat softens the fibres so the flute forms cleanly and helps the starch glue set into a strong bond.
Which machine forms the flute?
The corrugation machine or single facer, using heated grooved rollers.
