Increase uhle box dewatering, reduce needed vacuum - case studies

Aug 6, 2019

The combination of Valmet Hard Coating Solid and the perforated Valmet Uhle Box Cover have proven to increase dewatering at current vacuum levels, or reduce vacuum needs at many mills.

Valmet Hard Coating Solid

Valmet Hard Coating SolidValmet Hard Coating Solid (earlier known as SolidCoat) dewatering elements are hard-coated stainless steel components that cover the full width of the machine line. The surface of the components is solid, uniform and continuous without harmful joints on the fabric contacting surface. These dewatering elements are an excellent alternative when a mill is seeking energy savings, better paper quality and reliability.

Technology behind the new coating

Applying metallic bond layerValmet Hard Coating Solid comprises two layers - a metallic bond layer and a ceramic layer - over the stainless steel body being coated. The metallic bond layer is fourth generation HVAF applied ~100% dense corrosion resistant metal (less than 0.1% void volume). This layer acts as a transitional bond layer between the ceramic layer and the vacuum element body, as well as a corrosion resistant barrier. It improves bonding of ceramic to steel and prevents corrosion for optimum cover life.

The ceramic layer has engineered surface properties to maximize wear resistance and surface cleanliness. The optimized wear resistance is 1200-1300 HV3. The ceramic powders and sealing compounds are proprietary materials developed by Valmet.

Valmet Hard Coating Solid is used in many applications

Valmet Hard Coating Solid is used in many applications

Valmet Hard Coating Solid is used on new and existing machines at many locations, including uhle box covers, transfer suction box covers, vacuum forming boards, and many more. It is designed for gentle fabric contact, withstands all process chemicals and is thermal shock / impact resistant.

Valmet Uhle Box Cover

Valmet Uhle Box CoverThe perforated Valmet Uhle Box Cover coated with Valmet Hard Coating Solid is an effective and straight-forward solution to increase dewatering and reduce energy consumption in the press section. The sheet undergoes a long dwell time in the vacuum zone, increasing the felt dewatering at a lower vacuum level than a traditional slotted cover. The friction between the cover and the felt is decreased.

The Valmet Uhle Box Cover is recommended for mills with energy savings targets or runnability issues in the press section, especially if there is too much water for the 1st press to handle. Mills running board grades where the main part of the dewatering is done with uhle boxes find the Valmet Uhle Box Cover valuable, especially if they are using or want to use seamed felts. Mills making heavier paper grades, where the use of uhle boxes is essential for machine performance, are also choosing Valmet Uhle Box Cover to improve their operations.

Proven results!

Using the perforated Valmet Uhle Box Cover, mills can expect cost savings and benefits through:

  • Increased dewatering
  • Better runnability
  • Better profiles
  • Lower friction and lower press drive load
  • Longer felt lifetime and longer felt change intervals

There are many examples of Valmet Uhle Box Cover saving mills money and improving their operations. Here are just a few of them...

Propapier PM2, Germany

Valmet supplied a perforated Valmet Uhle Box Cover for PM2. Dewatering increased substantially at the bottom felt of the first press. Vacuum utilization was reduced by more than 20%. And they have achieved excellent moisture profiles with the new cover. (corrugated board base paper, 10.8m wire width, 1900 mpm design speed)

Powerflute Savon Sellu BM1, Finland

This mill wished to increase water removal on the pick-up felt, decrease splashing on the pick-up roll and improve runnability. They installed a perforated Valmet Uhle Box Cover and surpassed their goals. Dewatering was increased by 30% and vacuum level was decreased by 28%, with consistent moisture profiles. (fluting, 7.0m wire width, 700 mpm design speed, 110-200 g/m2 basis weights)

Orora Ltd. Botany BM9, Australia

After installing the perforated Valmet Uhle Box Covers on BM9, the felts are cleaner and there is no more need for chemical washing. The mill was also able to turn off one box per felt. Due to better felt conditioning, the mill increased felt lifecycles from 5 to 6 weeks. This reduced production costs while increasing efficiency and productivity. (container board, 6.2m wire width, 1600 mpm design speed).

Don't take our word for it, try a perforated Valmet Uhle Box Cover with Valmet Hard Coating Solid technology yourself and achieve the impressive results many Valmet customers have experienced! Contact your Valmet representative to learn more, and check out the Related Links for more information including a case study of results achieved at a North American mill.