It is best to clean rollers after print run. at colour changes and between long runs to ensure longer roller life and print quality. At least once four weeks, or if fast-drying inks or dusty paper have been used. the rollers should be thoroughly cleaned. inspected and regenerated with the appropriate maintenance agents. Never use wire brushes, paper or other abrasive matenals for cleaning and use aggressive wash-up solutions sparingly.

ROLLER SETTING

A roller will only perform effectively if it has been correctly set. If it is too light it could lead to ink variation or damping solution transfer If the pressure is too severe. the resulting heat build-up could lead to the breakdown of the roller covering plus premature wear. Check with the supplier if in doubt.

To avoid uneven setting. which would result in overloading. care should be taken to ensure that rollers are always set parallel to each other. In other words. the nip is constant over the whole of the length of contact. If the full forme width is not being printed. the parts of the roller not inked-up should be protected from running with oil or acid·free grease. Check with the machine manual or contact the press manufacturer the correct nip settings.

TRANSPORT AND STORAGE

When moving rollers, never let the covering come into contact with anything and when storing. support them only on the shaft. do not rest them on the covering surface.

During storage. protect the covering from direct light and and keep the relative humidity at around 65 per cent The surrounding temperature should be kept to between 20 and 30 deg Do not store rollers near electrical equipment which may give off ozone.

SPECIALISED ROLLERS

There are awide variety of specialised rollers used in print. Examples of the more popular ones are hickey pickers (to reduce loose fibres affecting print quality). EPDM grades for 100 per cent ultraviolet printing and polyurethane rollers. used for blanket washes. Before using a special roller. always consult the supplier to ensure compatible washup and maintenance products are used.