Paper Technology Journal 17 - Voith

Volume Loss (%)
7.5
5
2.5
0
Strato-
Size
Top-
Size HPX
Magna-
Size II
Standard
Rubber
6 month run time it was found that the
competitor’s cover had four times more
wear than the StratoPress cover. Unlike
the competitor’s product, the StratoPress
had little hole cupping.
The improved durability and the consistent,
efficient dewatering ability of the
blind drilled StratoPress cover was seen
in the machine performance.
During this 6 month run the customer
was able to set a new speed record for
the machine on 42lb. (205 g/m2 ) linerboard
of over 3000 fpm (915 m/min) for
four consecutive days.
Lab results of abrasion testing comparing
the volume loss of StratoSize to TopSize
HPX showed a 46% decrease in volume
loss. Fig. 3 shows the volume loss of
several roll covers.
This increased resistance resulted in
more uniform operating conditions on a
large European graphic paper machine
producing multi-coated paper in one of
Service
our first major field trials of StratoSize.
Previously, TopSize HPX was the preferred
cover at this mill due to its abrasion
resistance and excellent sizing properties.
StratoSize has the same excellent
sizing properties while maintaining these
properties over the run cycle.
Fig. 4 shows the difference in roll diameter
versus target diameter between Strato-
Size and TopSize HPX over similar run
periods on the above mentioned multicoated
paper machine.
Another property required for uniform
coating and sizing application as well as
stable sheet release is surface roughness.
A rougher surface allows for easier
sheet release. Fig. 5 shows the roughness
value of several rubber covers at installation
and after the run cycle.
The Strato series has a higher surface
roughness which remains rougher during
the entire run cycle. This results in more
consistent and uniform coating and
sizing, and fewer operational changes
Fig. 3: Volume loss of several roll covers.
Fig. 4: Difference in roll diameter.
Fig. 5: Roughness value of several rubber
covers at installation and after the run cycle.
Installation
Removal
3 +0.08
4 5
+0.04
0
-0.04
-0.08
+0.08
+0.04
0
-0.04
-0.08
TopSize HPX
StratoSize
1.5
1
0.5
0
Magna
Series
HP HPX
Series Series
Change in Ra, m
Strato
Series
47
during the run cycle as the surface characteristics
of the cover are more stable.
These product improvements are possible
because of the formulation and manufacture
of the Strato Series cover. Not
only did we develop unique combinations
and ratio of raw materials used to manufacture
the cover, but we also optimized
each individual raw material used to provide
the desired physical and chemical
properties of the cover. The formulation
of the cover compound is responsible for
surface wettability, surface tension, resistance
to surface deposits, hydrophilic/
hydrophobic sites and other cover characteristics.
All of these characteristics
have an impact on the performance of the
roll cover in the paper machine.
At Voith Paper we continuously use
our process know-how and Research
and Development to bring new products
to the market. The Strato Series
of rubber covers is our newest product
line to meet the increased demands
of our customers.
17/04