At the end of this module, you will be able to:
- Explain the purpose of the winder slitting process
- Identify and describe hazards and safety guidelines applicable to winder slitters and slitter sections
- Describe common slitting methods and identify the method most often used during winder slitting
- Describe the advantage of individually driven bottom slitters over a driven bottom slitter carrier roll
- Describe slitter setup parameters
- Describe automatic slitter positioning systems
- Describe slitter variables which influence slit quality
The following key questions are answered in this module:
Why are bottom slitters driven slightly faster than the sheet?
The overspeed prevents buckling and bunching up of the sheet at the entrance to the slitters.
There are several different slitting methods - water jet, razor, score/crush, and shear. Which is the most common?
Shear slitting is the most common method used on paper and board machine winders because it gives high quality cuts on a wide range of grades at relatively high speeds.
Why is each bottom slitter driven instead of mounting all of the bottom slitters on a driven carrier roll?
Because the carrier roll diameter must increase as the winder speed and machine width increase, in order to control vibrations, individual motor slitters have become more popular.
They are often referred to as ""knives,"" but only the top slitters look sharp. How do most slitters cut the sheet?
On most winders, the top slitters are sharp circular blades and the bottom slitters are bands. The top blade slightly overlaps the bottom band and is loaded from the side to cut the sheet using a shearing action, like scissors.
When roll sizes change, how are the slitters repositioned?
Slitters can be repositioned manually or automatically. Manual positioning exposes workers to hazards and takes longer, so is more appropriate when slit widths don't change very often.
Below is a transcript of the video sample provided for this module:
The slitter section of a winder typically includes multiple sheet guiding and support rolls, the slitters themselves, the spreader rolls before and after the slitters. The slitters cut the sheet into the desired roll widths, and also trim off the front and back edges. Depending on the grade, the number of slitters can vary from three or four up to 20 or more. Slitting is typically accomplished by multiple pairs of rotating knives mounted on shafts or rails. The cuts or slits are made at the points where the top and bottom slitter knives make contact. On paper and board machine winders, the top slitters are typically circular blades and the bottom slitters are usually bands.
Use the additional resources and links below to learn more about this topic: