Wool felt sleeves are made and dispatched with an internal diameter bigger than cylinder diameter.It is advisable that wool felt sleeves are kept into original packing until you do not have to use them, into a percet dry room, absolutely with no humidity.
A) The wool felt sleeve is in touch with liquids
In this case we recommend a metal cylinder with monting system: thermo-shrinkable. Cylinder may be smooth or have a light spiral rifling from left to right. Thru the action of the water the fixing of the sleeve is due partially to the rust process.
B) The wool felt sleeve is not in touch with liquid (dry use)
Cilynders surface – in this case must be very row. This kind of surface may be obtained with a lathe, with a light pitch and making an alternate movement left/right.
In alternative, you can make lines parallel to the cylinder axle at the distance of 40mm: these lines keep both the adhesive material and the felt sleeve. In any case the surface must be clean.
Before putting the glue on cylinder, it is advisable slipping the felt on the clean surface, in order to check that there is enough play between cylinder’s surface and sleeve.
MOUNTING OF FELT SLEEVE
First of all you must check that felt is not wet, or moist/damp and you must eliminate any residual of dust or dirt blowing it with compressed air.
A room moisture higher than 70% makes the effect of thermo-shrinkability of felt, with the consequence circumference’s shrinking, not necessary at this stage.
– Only thermo-shrinkable / in case in touch with liquid
– Glued or thermo.-shrinkable / in case of dry use
Sleeve must be slipped upon cylinder (which must have been worked and cleaned as above told) keeping into consideration the direction for mounting, printed on sleeve. Beginning from the center towards both ends you must wet it uniformly with hot water (approx. 60-80°Celsius).
Ii is advisable adding to the water a cross-linking agent or eventually a neutral detergent, in order to speed up the shrinking process.
In this way the sleeve comes back to its initial dimension, blocking upon cylinder (do you remember during the final stage of manufacturing the felt had been enlarged to a bigger diameter to be put on cylinder).
After this operation it is better wetting felt with cold water to stop the process and to dry it up slowly at a temperature of about 30 / 40° C.
STICKING AND SHRINKING
You must spread a uniform coating of adhesive upon cylinder prepared as above told. Usually the glue is at high viscosity therefore you should use a wooden or metal spatula. In particular be careful that upon the whole surface you make an uniform coat of glue. On the other side the internal surface of the felt sleeve must be spread at the both ends for only a length of about 30 cms.
As soon as the sleeve is put upon the full cylinder, you must manually press beginning from the center to the external well pressing the whole circumference.
Then, from the center towards the external, for the whole surface, you must wet felt with hot water. After having wetted it,you must roll cylinder upon a clean surface. Drying must be made at a temperature of about 60° C.
As soon as felt is dried you may conclude operation shortening the sleeve at the required working length.
As per our experience a sleeve well stuck and shrung is so much tightened to the cylinder that may be detached only on the lathe using a punch.
If you should wish a smoother surface, grind it in the sense of the fibers, upon a lathe with a dresser at high number of turns/tangential speed. Grinding paper must be fine >80.