29
3.3.2 WP-400 bottom unwinder
This is the most basic type of unwinding (see fig. 3.4). The film placed on the WP-400
unwinder can be routed via 3 rollers (see routing picture), appending of film type, the routing
can be changed. The routing showed in this picture is best for rigid film types, this creates
more tension during unwinding and results in a smoother film infeed. If flexible film is used, it
is recommended to bypass roller “2” at machine side.
Extra film tension during unwinding is created by the cover that rests on the film roll, which
also prevents the fiilm unwinding by itself. The weight plate is mounted on two slots to enable
changing of the weight on the film roll.
By moving up the weight plate, the weight on the film roll will be decreased. By pulling down
the weight plate in its slots, the weight on the film roll will be increased.
The film roll has to stop unwinding simultaneoulsy as the film advance stops. Also we need
just enough tension in the film during unwinding to avoid wrinkles in the film as it runs into
the chains.
3.
2.
1.
Figure 3.4 WP-400 unwind
Weight plate
Tracking adjust knob
