water wringer rolls, oiler rolls, non-woven rolls and 3M Mill Rolls from JVM
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JVM Transport rolls - Worldwide Use

as brake, bridle, steering, transport, pinch (driving), deflector or tension rolls

JVM tension and bridle rolls build up controlled tension levels due to their high frictional values whereby the coil material does not droop, and the wound coil is kept tight. In many cases rubber or polyurethane coated rolls, as well as steel rolls, do not have enough friction to produce sufficient tension. They often lead to marks or scratches on the strip caused by the speed differences (relative speeds) between rolls and strip. This slippage is particularly common when the strip is wet or oiled. This is because the surfaces of these rolls are not porous and a thin liquid film forms between the rolls and the strip material, which consequently causes the rolls to aquaplane. JVM special fibre coverings have a porous surface, with up to 40% void volume. The solution (liquid) is absorbed by the JVM Roll, creating a considerably better contact between the JVM Roll and the strip surface. This results in a substantially higher frictional value compared to conventional rolls

Advantages of JVM Rolls:

Extremely high, constant friction value, for example in comparison with rubber coated roll surfaces
  - 50% higher on dry strips
  - up to 40 times higher on oiled strips
Non-marking roll surface
The roll surface does not become "glazed" like rubber, polyurethane or comparable plastic coated rolls
Roll surface is resilient and extremely resistant against cuts from strip edges
No aquaplaning/hydroplaning or air planing
Very long life
Increased productivity of the line
  - higher strip speeds
  - considerably higher strip tensions
  - no scratching of strip surfaces as a result of strip slipping
Tighter wound coils
Better strip control
More precise coil winding
More consistent movement of strips and better strip control during follow-up treatment in continuous annealing furnace

Also for pinch (driving) and brake rolls, a higher and constant friction value is required, particularly in case the strip surface is wet or oily. Conventional rolls have low friction values even when they are new, and generally deteriorate significantly after short time of operation. JVM Rolls are perfectly suitable for these different tasks, regardless of the strip surfaces being dry, wet or oiled.

Comparison or Friction Factors, Data of the Friction Values in µ

JWM Roll Rubber Coated Roll
Steel strip
Dry 0,52 0,36
Wet 0,44 -,-
Oily 0,36 0,01
Stainless Steel strip
Dry 0,29 -,-
Wet 0,27 -,-
Oily 0,25 -,-
Aluminium strip
Dry 0,29 0,36
Wet 0,31 -,-
Oily 0,32 0,01
Copper strip
Dry 0,34 -,-
Wet 0,31 -,-
Oily 0,34 -,-
Brass strip
Dry 0,34 -,-
Wet 0,37 -,-
Oily 0,30 -,-

Note: Coefficients of friction measured with a strip guide of 180° (see schematic drawing)