1. String-Like Fiber Dust Occurrence in Crush Cutting of Stacked Liner Boards

To convert a corrugated fiberboard (Cfb) into a couple of unfolded formed-cut sheets for making a container box, since the raw Cfb is cut off by using a combination of center-bevelled (wedge) blade and its counter faceplate, the cutting edge of blade dynamically and repeatedly collides on the faceplate. Therefore, the edge profile of blade and the contact zone of faceplate plastically deform and abrasively removed with respect to the repeated cutting times. When the cutting times of raw Cfb increase and reach a certain number, the occurrence probability of string-like dust empirically increases due to the variation of edge profile of blade and dent of faceplate. When such the string-like dusts become larger and adhere to the product object, they become foreign matter. Therefore, in order to reduce the occurrence of string-like dusts, any countermeasures are required. Nagasawa et al. (J Jpn Soc Technol Plast (SOSEI-TO-KAKOU) 43(498):624–628, 2002, [3]) had reported about the effects of blade tip thickness on string-like dust occurrence in the case of white-coated paperboard of basis weight 350 (a thickness of 0.45 mm) and the correlation between room humidity and dust occurrence probability. However, any generation mechanism of string-like dusts and its applicability of occurrence estimation to a Cfb are not sufficiently discussed in the past. When the Cfb is subjected to a pressure cutting of flatbed die cutter, a stacked collection of three raw fiber sheets, upper liner, medium, and lower liner sheets, is fasten and cut off by a wedge indentation. These raw sheets have a thickness of 0.18–0.22 mm, which is relatively thinner than that of widely known white-coated paper of 0.45 mm, and these three raw sheets have different mechanical properties for each layer. Synthetically, the occurrence probability of string-like dusts in the Cfb cutting appears to be partially different from that of the white-coated paperboard. The authors experimentally investigated the relationship between the blade tip thickness and geometrical features of string-like dusts and the corresponded cutting load responses, in order to reveal the mechanical condition for causing the string-like dusts.