Trim removal on slitters

A trim fan attached to a slitter.

As discussed previously on this blog the process of slitting (at its most basic) can be reduced to the one-line description of 'a big roll is loaded on one side of the slitter rewinder, and smaller rolls are loaded off the other side' and that's fine... most of the time.

Here comes the example!
If a 1000mm wide roll is loaded onto a rewinder and is slit down into rolls that are 212mm wide then four rolls would be produced.  If your mental maths is up to scratch you might have noticed that 4x212 does not equal 1000, and that means that from the original / master / jumbo roll there will be roughly 117mm left over.    Sometimes this happens because the edges of jumbo rolls are discarded due to damage, print reasons or simply because the material being slit isn't coated all the way to the edges of the roll.

So what happens to this waste material?
Waste material can be wound onto cores in the same way 'correct' rolls are, but sometimes it is preferable to discard this waste rather than collect it, and that's where trim removal comes in:

A quick look at a couple of slitter trim removal methods:

• Trim winders
  Trim winders do exactly what you would expect them to, they wind trim on a part of the machine set apart from the rewind section of the slitter.  The advantage of using trim winders is that trim can be collected in such a way that operators only need to remove the collected waste once every few jobs, rather than at the end of every job.  Trim winders can also help maintain web tension.
  
• Trim blowers
  Trim blowers do in fact work by sucking... sort of.  By using a venturi pipe or a suction tube waste trim is simply sucked away from a position close to the point of slitting and carried to a central collection point or dropped into a bag that looks like a big fishing net.  A venturi pipe is a 'Y' shaped pipe that creates a vacuum effect when air is passed through it.

All methods of trim removal have their upsides and downsides, so choosing the most efficient method for your own processes is vitally important, and we're here to help.