For four years now, Propapier has been producing 70 – 115 g/m² corrugated base paper on their PM 2 at the Eisenhüttenstadt mill on the River Oder. The production and technology management team decided last year to upgrade their PM 2 sizer rolls, which were due to be re-covered. The rolls were fitted with an eVen rubber polymer cover and an integrated NipVision high-tech measuring system, both of which are Voith products. The papermaker wanted to achieve three goals through this investment: more uniform pressure conditions in the roll and rod nips, lower temperatures during size application and longer regrinding intervals for the roll covers. Achieving all these goals would allow the mill to improve the surface quality of the paper and at the same time significantly reduce maintenance costs for the rolls. Evaluating the first three months of operation confirms that all three goals have indeed been reached.

Real-time measuring system in the roll nip. NipVision consists of glass fibers inside the roll cover and an external electronic unit. The glass fibers function as sensors, recording dynamic pressure and temperature conditions in the roll cover. The measured data is transmitted offline to the electronic unit, allowing the machine crew to continuously check the actual conditions in the roll cover and nip in real time. If temperatures rise too steeply or pressure conditions deviate too much over the web width, operators can intervene and make the necessary corrections. This prevents damage to the roll cover from too high temperature and at the same time improves paper quality.

Even before Propapier opted to purchase the covers with built-in sensors, Voith had already acquired very good experience with NipVision in other paper mills and applications in the press, size press and calender. The opportunitiy in Eisenhüttenstadt was for NipVision to visualize not only the sizer nip but also the metering rod pressure on both rolls at the same time. The specialists from Propapier and Voith were therefore excited to see the initial results – and they were not disappointed: Right away, the new roll covers produced an impressive performance in operation.

The eVen covers consist of a rubber polymer matrix which is specially developed for use on size and film presses. Christian Schulze, Application Finishing, expressed his enthusiasm after the first 16 weeks of operation: “We have now been running the eVenSize roll covers for twice as long as before and there is still no need to change them. This means that we have so far already saved the expense of the special transport for regrinding, the costs for the regrinding itself and downtime for the unit.”

The upgraded rolls from Eisenhüttenstadt were brought to the Voith Service Center in Laakirchen for the first time after 20 weeks of continuous service. Measurements taken there confirmed that eVen is more rugged than conventional sizer covers. During the roll service, the cover roughness was measured and surface quality analyzed. Both values were excellent, given that the covers had been in use two and a half times longer than the previous product. In addition, the amount of material removed in the regrinding process could be kept to a minimum, so that from today’s perspective there are good grounds to be very optimistic about the expected total service life of the covers.

The NipVision measuring and sensor system also performed very well in Propapier’s coating unit. Production Manager Stefan Jürgen confirms that the benefits pay off: “The temperature monitoring in both the roll covers enable us to even out the normal fluctuations. This not only preserves the roll cover but also improves the application of the size. Using NipVision, we are able to keep the pressure conditions largely stable. For us as papermakers, NipVision has literally made a vision reality: It has made the invisible visible!”//