Paper Machine Felt Circuits, Re-designing May Improve the Performance

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Read Expert's view over Paper Machine Felt Circuits in Paper Making Industry.

Paper Machine Felt Circuits, Re-designing May Improve the Performance

Paper industry uses different  types of felts for different products. That is perfectly OK. We use different felt circuits. Each circuit contains a stretcher, a guide and several other rolls. If you look at various felt circuits, these are in different shapes. Most of you must never have tried to look beyond the felt circuits. In any felt circuit, there are several rolls which have very little wrap angle, while some rolls have bigger wrap angles. For example, the stretcher might have a full 180 degree wrap angle, while the wrap angle of felt on the guide  roll is typically around 35-40 degrees. Have you noticed that the most of the bearing related problems appear on the felt rolls which have more wrap angles? Another point is the  number of rolls in a felt circuit. Typically, the more number of rolls inside the felt circuit results in more time the machine crew needs to change the felt. That means having lesser number of rolls inside the circuit will definitely help to reduce felt change downtime.

This way, two major variables appear. First is the wrap angle of the felt on the roll, and the second is the number of felt rolls inside the felt circuit. First may result in increased bearing related problem, while the second results in increased downtime to change the felt. So, what can be done? Many maintenance experts recommend using genuine bearings, sleeves, using additional lock washer, mounting the bearings properly etc. Of course, most of our maintenance engineers are doing their job well. Compared to past decades, the bearings reliability has increased drastically. But, is it not the need by the design engineers to look into the issue and design the felt circuits with smaller wrap angles? Today, we are proud that India is fast emerging as a reputed paper machine manufacturing country.

Many Indian suppliers have earned great reputation by supplying world class machines at competitive prices. I wish suppliers should also consider the issue an important one and start designing felt circuits considering the same issues in their forthcoming supplies for paper machines. All paper makers should also review felt  circuits in their machines, and discuss with machinery manufacturers for some possible upgrade, if needed.

Please think.

Article submitted by: Mr. Devesh Kumar Singhal, B.E., M.E. (Pulp & Paper), Chartered Engineer, Certified Energy Auditor Chandpur Enterprises Ltd. India (see the photo)

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