Automation for Managing Warp and Waste

automation for managing warp and waste

Every corrugated mill is different—so why are so many plagued by the same problem? Cross-direction (CD) warp is a common issue that can cause an incredible amount of wasted time, energy, and product.

Multiple drying and rewetting cycles throughout the process create multiple opportunities to introduce the potential for warp. The fluctuations in CD moisture and temperature variation causing sheet warping seem impossible to correct with standard corrugator controls. In the words of Dave Maddux, IQ corrugator solution manager, North America for Valmet, “Paper machines use moisture control … why not do that on the corrugator?”

The Valmet IQ system for corrugators combines precise online moisture, temperature, and warp measurements with reliable closed-loop controls and moisturizers (see sidebar). In this exclusive Paper360° interview, Maddux tells us why he’s excited to bring this technology to the North American corrugated industry.

P360: Why is warp so challenging to address?

Maddux: Cross-direction warp is caused by uneven tension, because of moisture changes during the process, between the different layers in corrugated board—especially in the inner and external liners. Our system addresses that moisture imbalance.

Speed changes, paper quality parameters, variations inside the reel—especially in splicing from one reel to another—all make the process inconsistent in the heating and rewetting. In order to control, you must have a measurement, right? Well, right now most corrugators don’t have that important data.

Were there specific “pain points” you were trying to address for corrugated industry customers?

If you need to make it twice, you’re costing yourself money. We help reduce waste, and help the corrugators produce a flat sheet, a flat board, with the correct moisture content. What makes us different is that we’re also controlling, to a minimum temperature, for bonding.

The system can control the moisture on each layer. We have a sensor that reads each layer of the sheet, and thus we can control the moisture and get that balance. We’re gluing at the right temperature, and at the right moisture level, so when the sheet comes out the other end you’re not getting warp. We want the production team on the corrugator to be able to see the online moisture and temperature on different parts of the machine. It’s a closed-loop control, which is not unusual in the paper industry but is unusual in the corrugator industry.

When considering a range of automation solutions, how can mill managers decide what is the best option for their plant?

Corrugators are very unique; they’re all somewhat different. We can go out to the plant and do an audit; we’ll look for bottlenecks on the corrugator machine to find the correct solutions for that plant’s needs. We can break up the system according to the needs of the customer, providing only the parts they need.

Today’s “state of the art” is always a building block for what comes next. Any predictions about the next level of technology for the corrugated industry?

Digitalization will continue, and the systems will be more connected. One thing we’re working on with customers in Europe is passing the data from the papermaker to the corrugator—taking quality information into account when running certain rolls together, then passing information back. I see that in the future: we’ll be transferring data in both directions, to improve efficiency. AI will help us automatically choose the correct reels for the right job on the corrugator.

We’re all trying to go carbon-neutral, and Valmet is a big proponent of that. The IQ System can help in two ways; the big one is by decreasing waste, the other is by decreasing energy, because you’re not over-heating the sheet.

Generally, our ROI is less than a year. We usually see about a 40 percent reduction in waste. Plus, using less heat means using less energy. We are looking for our first installation in North America; we have more than 40 installations in Europe. I’ve been to visit some of those installations in Europe and that’s why I’m so passionate about this product—because I’ve seen it work.

Dave, I know you’re also passionate about helping young people discover automation careers. Any advice for helping corrugating manufacturers attract the next generation of engineers?

To attract engineers at that professional level, corrugators need to make it clear that they’re on the edge of some interesting technologies. They’re being asked to do more with less. It’s an opportunity for young engineers to be part of the changes that are coming for the corrugated world. If an engineer is a true problem-solver, this is an opportunity for them to be on the ground floor of some interesting changes.


About the IQ System

Valmet IQ for Corrugators uses a unique quality control system (QCS) that stabilizes raw material and process variations throughout the value chain—from fiber to finished product—and optimizes both process performance and sheet quality in the corrugator. Components include:

Valmet IQ Warp Measurement: Used in automatic closed-loop control (MPC), together with Valmet IQ Moisturizers, to achieve warp target fast and without further actions. IQ Moisturizer can handle all kinds of warping (S-warp, CD-warp, edge-warp) correction and moisture CD profiling in corrugators.

Wet-end control—Valmet IQ Multipoint: This measurement system gives precise moisture and temperature information to Single facer & Triplex pre-heater wrap-arms for automatic process control to reach optimal conditions for gluing to ensure bonding, prevent warping, and decrease washboard effect.

Dry-end control—Valmet IQ Single-sided IR moisture measurement: This provides accurate moisture and temperature measurement for closed-loop control. Together with IQ Warp control and IQ Moisturizers, the final moisture of the sheet can be optimized, which improves end-product quality and stabilizes the process even further.

Valmet IQ full QCS: Valmet’s model-predictive multivariable IQ Wet-end and IQ Dry-end controls integrate online quality measurements, IQ Moisturizer, and existing machinery components for maximized corrugator speed, sheet quality, and site productivity in all process conditions, all the time.

Valmet DNA User Interface: This new web-based user interface can be used with Valmet IQ, and guides operators to focus on the situation-critical information to make the right decisions instantly.

Valmet IQ Quality Data Manager: This Valmet Industrial Internet (VII) application connects paper production and corrugator processes seamlessly together and provides instant information through the value chain. The paper quality data moves between the paper mill and converting, for a totally new way to control the process.