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What is Reduced Bead Creasing?
- Introduction - Reduced Bead Creasing, theorized and taught by international consultant Kevin Carey of Diecutting Information Exchange, is a process of producing scores, or folds in folding cartons, or other paperboard stock with smaller "beads" in which the outer layer of paperboard will experience less tension during the fold and resist the tendency to crack. Improving the appearance and eliminating the cracking of creases in a folding carton or other printed, folded material has long been a goal of numerous printers and folding carton makers. One of the methods tried was to use a small creasing channel. When it worked, the process was adopted, but not defined as a new theory. It was just known to have worked on a particular job.
- Theory - In order to create these smaller beads, it is necessary to decrease the critical distance, which is the distance between the rule's edge of the matrix channel. It should be noted that as well as decreasing the critical distance, the depth of the channel is suggested to be one half the thickness of the board caliper. The rule of thumb in the past has been to allow this critical distance to be at least equal to the thickness of the paperboard stock that is intended to be creased. By reducing this distance, the degree of internal delamination increases, allowing the layers of paperboard to be easily forced into a smaller channel, creating a smaller bead. This procedure can be accomplished in two ways. One, by increasing the pointage, or thickness of the creasing rule, and two, by reducing the size selection of the matrix channel. There are obvious advantages to increasing the rule thickness, but where it is impractical, or not economical to change the entire creasing rule in a die, changing the matrix strips is an option.
- Corrugated Creasing It should be noted to accomplish creasing in corrugated materials, the process is entirely different. Board delamination does not occur in creasing corrugated. Rather an action of crushing the outer layers and the inner flutes occurs, which does not necessarily create an inner "bead" of material. However, under the right conditions, using a channel matrix, a bead can be formed. Because of the many variations and the basic structure of corrugated itself, it is almost impossible to set a standard channel width selection to accomplish reduced bead creasing. However, the use of creasing matrix in corrugated materials is becoming ever more popular as demands for more attractive packaging rise.
- Conclusion Reduced Bead Creasing is a problem-solving tool to be used in cases where cracking occurs during the folding process. For this tool to work in your application take all considerations into account. Board type, moisture content, operating conditions, and press conditions are just a few to keep in mind.