Tips

Typically, bowed rolls are used to separate slit widths. If you are using a bowed roll for separating slit widths, it is a good idea to place an idler roller immediately following your slitting station, prior to the bowed roll. So, the web will first enter the slitter, then, after the slitter thread around an idler roller, then flow over the bowed roll for slit separation.

The reason for this is the operating principal of the bowed roll. Bowed rolls separate slit widths because of the web handling principal that a web will seek a 90 degree angle to a roll in its entry span to that roll. After a web is slit, each of the slit widths will try to maintain a 90 degree angle to the curved axis of the bowed roll. This slit separation takes place in the unsupported web entry span to the bowed roll. If that unsupported web length spans back to the slitter, the slit widths will start separation at the point where they are being slit. This separation could cause the slit web lanes to tear, instead of being cut efficiently by the slitter knife. Tearing instead of slitting efficiently will cause excessive dust and poor slit edge quality.

Placing an idler roller between the slitter and the bowed roller will eliminate this potential problem. With this idler roller placement, the slit lanes of web will each seek to be 90 degrees to the flat idler roller face. This keeps each slit lane running straight, immediately following the slitting station. No tearing will occur due to slit separation.

The slit lanes will separate in the unsupported web distance, between the flat idler roller and the bowed roller. Bottom line, if you currently use bowed rollers to separate slit widths and you do not have an idler roller placed between the slitter and the bowed roller, you may need to place a flat idler roller between the slitter and bowed roll to improve slit quality and reduce or eliminate slitting dust.