Mechanics of slitting and cutting webs

The quality of edges formed during cutting and slitting of thin polymer webs is important for many industrial applications. To control the edge quality of the separated material, it is necessary to understand cutting. A model is proposed, and the mechanics of cutting are described. Experiments were conducted on polyethylene terephthalate. Photoelastic micrographs were used for qualitative and quantitative observations of the two-dimensional stress distributions. The results of this analysis supported the model for cutting of thin polymer webs. An apparatus was constructed to instrument, monitor and control the web-slitting process. The slitting speed, tension in the web and angle of cut were varied during tests. This allowed a quantitative understanding of the cutting mechanisms to be established. The results of the experiments showed that the in-plane cutting forces were minimally affected by changes in rate or web tension. The angle of cut had a pronounced effect on the in-plane cutting forces and the stability of the cut. The results are a beginning of a mechanistic understanding of deformation taking place during slitting and cutting. The experimentation emphasized an instability in slitting. An understanding of this instability will allow quality web edges with minimal deformation and straight stable cuts to be achieved.