Sheet crushing

1. Operate dandy correctly, namely:
(a) keep high-pressure needle shower blowing from inside and pointed up wire.
— keep dandy clean.
(b) install a steam shower to break the adhesion at the outgoing nip.
(c) avoid wet streaks going into dandy.
— do not let stock get too wet or too short.
(d) the dandy should be adjusted to just touch the forming fabric without stock.
— overdrive dandy by 3 – 5 m/min.
— the impression of the dandy on the sheet as it runs (looking up from below) should be about 2.5 cm.
2. Make sure that flatboxes are operating correctly and are not flooded.
— if necessary (and possible), increase vacuum.
3. Keep felt open.
— is design of felt appropriate to the service?
4. Maintain correct relationship between suction roll box and couching of solid press roll.
5. Make sure that doctors fit and that there are no water drips on felt.
6. Check crown, load and loading mechanism.
— the press may be pinching in center (the load is too little for the crown) or at ends (the load is too much for the crown).
7. Do not allow the rubber to wear so that the press jumps.
— ensure that shell is not uneven inside, causing box to jump.
8. If machine is old with solid presses, consider using:
(a) a shrink fabric cover.
(b) a Venta-nip press.
(c) a fabric press.