Most containerboard — fluting and testliner — is made from OCC (old corrugated containers). Some mills run virgin kraft or a blend. The choice is not only a raw-material decision; it changes the equipment you need and the strength you can sell.
What OCC brings to the line
Recycled fibre arrives as bales containing contraries: tape, staples, plastic, sand and stickies. The stock preparation line has to remove all of it, which is why OCC lines are heavier on cleaning and screening than virgin lines of the same tonnage.
- Pulping — drum or hydraulic pulper, sized for bale throughput rather than finished tonnage.
- Coarse and fine screening — pressure screens separate usable fibre from stickies and specks.
- Cleaners — remove heavy contraries before they reach the wire.
- Refining — recycled fibre loses bonding ability with each cycle, so refining matters more for strength.
What virgin fibre changes
Virgin kraft pulp gives longer, stronger fibres and higher burst and tensile at the same grammage. You need less cleaning and screening, and you can often reach a higher strength specification without as much refining. The trade-off is raw material cost and, in many markets, availability.
The practical consequences for equipment
- An OCC-based testliner line needs a larger stock preparation front end than a virgin line of the same TPD.
- Recycled fibre drains differently, so wire and press configuration matter more.
- Stickies control is a process problem, not only an equipment problem — ask what screen slot sizes and reject rates the line was designed for.
What to tell a supplier
State your furnish honestly: 100% OCC, a blend, or virgin. It changes the quotation more than buyers expect, and a line sized for virgin fibre will disappoint the moment you run OCC through it.