A range of web tension controllers... unwind, intermediate and rewind controllers with digital or analogue displays manufactured by CMC Controls Ltd.
UNWIND CONTROLLERS 
Utilising the same display features as indicators, all of the unwind controllers incorporate extra features like "SOFT START" to prevent tension transients when starting the machine, and "PARK" to prevent the unwind reel from rotating during machine stop.
The required tension is simply set by the operator. For the analogue versions, this is a rotary front
panel control. Digital versions use front panel "UP/DOWN" tension setting push buttons. The actual running tension is continuously and accurately displayed, providing important production information.
INTERMEDIATE CONTROLLERS 
Again having all the same display features as the unwind controllers, intermediate controllers are used in conjunction with motor drives. They provide accurate tension control between process sections on any web converting machine by using speed trim methods.
Suitable for use with most proprietary DC drives, intermediate controllers combine the web speed and tension error signals to give maximum performance.
Simple to retrofit, they give the ability to up-rate a process section, at minimal cost, as well as giving a continuous and accurate display of web tension.
REWIND CONTROLLERS 
Rewinds fall into two categories, either surface or centre, each needing different control requirements.
When surface rewinding, it is possible to use the intermediate controller model as both applications are controlled by speed trim methods. However centre
re-winders are usually operated in torque mode, and the controller must give a signal that is a function of the rewind reel diameter to determine the correct torque to be applied.
Webs of a slippery nature or having an uneven cross section thickness cause problems when centre rewinding. To obtain good rewound reels, the starting tension must be reduced as the rewind diameter increases. This action is known as "TAPER TENSION".
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