In die cutting manufacture of paperboard it is necessary to apply the correct creasing conditions, e.g. neither too small nor too big a rule height, in order to achieve sufficiently low folding resistance without any cracks along the folding lines. The most appropriate rule height for a given paperboard is usually determined by trying different rule heights in a series of very time consuming and costly trial and error tests. And, in practice, this procedure must be repeated for each major change in board quality. This report shows that an inclined crease rule, i.e. a rule having a gradually increasing rule height, can be used advantageously to rationalize such tests and to achieve much greater reliability. A folding line produced by such an inclined rule contains both the upper limit for the rule height, i.e. where cracks start to appear, and the lower limit, i.e. where the rule height is obviously too small, and the technical range for achieving a good creasing result is thus clarified in one single test. Illustrative data for two types of paperboard are given as well as some theoretical aspects of the concept of creasability. Considering that the described method not only rationalizes the testing work but also enables more reliable observations to be made than have been possible in the past, the method opens new potentials for effective research and development in the fields of converting, convertibility, die form design, etc.
In die cutting manufacture of paperboard it is necessary to apply the correct creasing conditions, e.g. neither too small nor too big a rule height, in order to achieve sufficiently low folding resistance without any cracks along the folding lines. The most appropriate rule height for a given paperboard is usually determined by trying different rule heights in a series of very time consuming and costly trial and error tests. And, in practice, this procedure must be repeated for each major change in board quality. This report shows that an inclined crease rule, i.e. a rule having a gradually increasing rule height, can be used advantageously to rationalize such tests and to achieve much greater reliability. A folding line produced by such an inclined rule contains both the upper limit for the rule height, i.e. where cracks start to appear, and the lower limit, i.e. where the rule height is obviously too small, and the technical range for achieving a good creasing result is thus clarified in one single test. Illustrative data for two types of paperboard are given as well as some theoretical aspects of the concept of creasability. Considering that the described method not only rationalizes the testing work but also enables more reliable observations to be made than have been possible in the past, the method opens new potentials for effective research and development in the fields of converting, convertibility, die form design, etc. © 1997 John Wiley & Sons, Ltd.
The crack propagation that occurs in corrugated board in connection with die cutting is analysed in order t o identify the most crucial liner and fluting parameters and clarify their relative importance.Based on an energy approach and the brittleness concept -L -' ( m -' ) -for the liner, a formula is derived. This formula is then verified exeprimentally for a large number of corrugated board qualities of different thicknesses and flat crush strengths as well as for liners with widely differing mechanical properties. The correlation can be regarded as very good.The analysis shows that crack propagation is dependent on three material parametersthe brittleness of the liner, the compression strength of the fluting in relation t o the tensile strength of the liner and the breaking strain of the liner. It is shown that crack propagation increases proportionally with increasing liner brittleness, provided that the other material parameters remain unchanged. The compression strength of the fluting layer contributes somewhat more than proportionally -by a power of 1.33. The crack propagation decreases with increased breaking strain, the relation is almost inversely proportional.In practice, none of the above mentioned liner parameters can be chosen independently of the others. The same applies t o the fluting parameters. When estimating the expected crack propagation in a particular corrugated board quality, it is necessary t o consider the contribution from all the mentioned parameters according t o the formula.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.