Roll change interval increased from one to two years with Lock Seal

Nov 18, 2020

Papierfabrik Adolf Jass is a medium-sized, owner-managed and family-run business. For over 50 years the mill has been producing ecologically friendly papers for corrugated paper packaging using recycled paper. The total annual capacity of both paper mill locations, Fulda in Hesse and Rudolstadt/Schwarza in Thuringia, Germany, is 1,000,000 tonnes of corrugated base papers.

Adolf Jass is one of the leading paper producers in Germany and Europe in the corrugated packaging industry. Ecology and economy go hand-in-hand in Adolf Jass Company. It means recycling paper, energy and water as effectively as possible. The concept of circular economy determines the corporate activities.

The three paper machines in both paper mills are ultramodern and comply with the state-of-the-art technology. The machines are constantly modernized and developed. Technical innovations are processed together with the machine suppliers and implemented the first time at Fulda mill.

In that respect, also the machine maintenance has a significant role in maintaining productivity. In Adolf Jass Company, the maintenance interval of the rolls equipped with axial seal strips was originally between 8 and 9 months. In order to increase efficiency also here, the targeted maintenance interval was increased to 18 months.

As paper producers are always looking ways to decrease production costs, new, durable materials requiring less maintenance are looked for. In rolls, the axial seals are the weak element with short lifetime. The suction roll axial seals are usually replaced in connection with every roll maintenance.

Target exceeded - roll change interval was increased from one to two years!

When recycled paper is used, more impurities are created compared with primary fibers. This may cause stronger seal wear. Since 2009, Valmet has modernized the suction rolls of PM3 and PM4 with Valmet Lock Seal seals. The lifetime of these axial seals varies between 1.5 years to 3 years depending of operational conditions.

In January 2017, after two years of operation in the PM4 suction roll with regular maintenance, the condition of the Lock Seal seals was so good, that they could have been reused. By using Lock Seal seals, the maintenance interval could be extended to 24 months. The customer has plans to extend the maintenance interval even more in the future.

Valmet Suction Roll Upgrade Lock Seal for non-contacting suction roll axial seals

Traditional axial seals load the inner surface of the suction roll shell constantly. High friction between the rotating surface and the axial seals can cause thermal stress cracks that can gradually grow and damage the shell. Lack of lubrication water or too high loading pressure would increase the friction between the axial seals and rotating roll. Lock Seal operates mainly without contact or with a very light contact with the inner surface of the roll. Thanks to low friction, the lifetime of the roll is increased significantly.

Valmet Suction Roll Upgrade Lock Seal enables reducing the lubricating water consumption in positions where lubricating water could cause moisture variations or rewetting. This has even enabled shutting off lubricating showers. The transfer suction roll between the 3rd and 4th press is a typical position, where a minimum amount of lubricating water is needed.

Thanks to low friction, rolls with Valmet Lock Seal seals require less energy. The seal is not constantly loaded against the roll when the paper web is running. The axial seal is relieved and a thin water film spreads out. Decreased shell wear is a result from lower friction.

The Adolf Jass Fulda mill chose the Lock Seal axial seal technology developed and patented by Valmet. Nowadays Lock Seal is a standard solution in Valmet's high-speed machines. Each existing roll including a competing product can be modernized with Valmet Lock Seal.

 Improved axial seal performance

  • Longer roll maintenance interval up to 24 months
  • Reduced shell and axial seal wear
  • Extended axial seal lifetime
  • Reduced friction, and reduced energy consumption - excellent return on investment
  • Improved moisture profile and less rewetting
  • Reduced lubrication water consumption and better running behavior under challenging lubrication conditions
  • Lower noise level
We have hit our target for increasing the roll running time and the system operates satisfactory. We would go for it any time again.”
Siegfried Brauchle, Mechanical Manager in Adolf Jass Fulda mill