Paper Machine Felt cleaning needs further attention. This paper raises issue and requests all concerned to join hands and get a solution.

1. RETHINKING PAPER MACHINE FELT CIRCUIT,
BY D K SINGHAL, JANUARY, 2016
deveshksinghal@gmail.com
1
Rethinking Paper Machine Felt Cleaning
Ever looked how does the press felt look like during felt cleaning? The following image shows this.
Did you notice the light and dark stripes in the machine direction? What are these? Why do these form?
As obvious, the light colored strips indicate that the felt has been relatively cleaned at that particular
area while the dark strips represent the unclean area. That indicates the quantum of unwanted material
in the felt.
Let us make some simple sample calculations-
Machine Speed: 300mpm
Time between Felt Wash: 4 days
Felt Length: 15M
Impurities captured by the felt: 200gsm (dirty felt gsm minus clean felt gsm)
Length Travelled in 4 days: 4 X 24 hrs X 60 Min X 300mpm
: 1728000 M
Passes of Felt: 1728000/15 = 115200
Impurities GSM increase: 200/115200 gsm/pass = approx. 0.002 gsm/pass
These calculations just show the magnitude of the contamination of the felt only on linear basis. In
practical, however, the pattern of felt contamination may vary with time after the felt cleaning. The
purpose of making such sample calculations is to just show the minuteness of the contamination with
every pass.

2. RETHINKING PAPER MACHINE FELT CIRCUIT,
BY D K SINGHAL, JANUARY, 2016
deveshksinghal@gmail.com
2
Coming back to the point, we can see that felt cleaning removes impurities from the felt. However, this
removal is non uniform across the width of the felt. This way, there are two issues with the felt cleaning-
1. We need to frequently clean the felt after every 3-4-6 days, resulting in production loss.
2. Felt cleaning process is not very efficient one.
In the present time, we are focusing more and more on reducing water consumption, and felt showers
are being replaced with smaller diameter nozzles, with optimized operating pressure to get the best
results. Still, we need to wash our felts on a regular basis.
Mills have tried different chemicals with some advantages, but still, there is a need to develop a perfect
online felt cleaning system that can totally eliminate the need to periodically wash the felt.
While relooking at the image above, one can understand that how efficient our online cleaning system
(shower and vacuum system) may be, but, we possibly lack uniformity in felt washing.
Let us all discuss the issue with felt suppliers, shower manufacturers, chemical suppliers, paper making
professionals and research and development organizations; and jointly explore the possibilities for
better felt cleaning/conditioning systems.