Warp on corrugated board is rarely a mystery. Moisture imbalance is. Sheets Unlimited—one of the Pacific Northwest’s largest independent corrugated sheet producers, based in Washington—has ordered a Valmet IQ Quality Control System for its corrugator to attack that root cause, not just chase symptoms at the stacker.

Valmet booked the order in Q2 2026. Delivery is planned for Q4 2026, with commissioning in January 2027. For a sheet feeder that buys roll stock from multiple mills, grade, moisture, and fiber variation make warp behavior hard for standard corrugator controls to tame—hitting converting yield, waste, and customer claims.

Valmet IQ for corrugator combines online moisture, temperature, and warp measurement with closed-loop automation.

What Sheets Unlimited is buying

The package includes combined paper temperature, moisture balance, total moisture, and warp control, interfaced to existing corrugator heating elements, plus Valmet moisture measurement technologies and an automatic moisturizing solution. Named components: Valmet IQ Warp Measurement, IQ Moisturizer, IQ Multipoint Moisture, and microwave moisture measurement under automatic closed-loop controls.

Flute geometry amplifies moisture asymmetry—small cross-direction imbalances show up as warp that converting lines reject.

Krist Leland, Director of Manufacturing at Sheets Unlimited, said the company evaluated Valmet’s warp control after seeing it run at a European manufacturer and focused on moisture-imbalance correction. David Maddux, Board Converting Automation Sales Manager for North America at Valmet, positioned the system for process stability, more uniform quality, lower operator workload, less waste, and better resource efficiency.

Closed-loop moisturizer and heat coordination is how Valmet argues sheet feeders can stabilize bonding across mixed mill supply.

Industry reading

Independent sheet plants live on consistency without owning the paper machine. Quality control that measures warp and moisture online—and writes back to heat and moisturizer actuators—is the practical middle between hoping mill specs hold and sorting bad board after the fact. The same logic shows up wherever converting quality depends on process sensors talking to control loops, whether on packaging lines or broader process automation platforms and plant PLC/PAC architectures.

Opinion

Buying a QCS for warp is admitting the corrugator’s native controls were never designed for multi-mill moisture chaos. That is a mature call. Success will be measured in converting claims and trim waste after January 2027 startup—not in the press photo. If closed-loop moisture truly owns the CD profile, Sheets Unlimited will feel it in the finishing department first.