Product Code: ICA11_108

Effect of Linear Cutting Energy on Coloration of Paper in Laser Cutting of Paper Material
Authors:
Alexander Stepanov, Lappeenranta University of Technology, Faculty of Technology, Laser Processing Technology Research Group; Lappeenranta Finland
Heidi Piili, Lappeenranta University of Technology, Faculty of Technology, Laser Processing Technology Research Group; Lappeenranta Finland
Esa Saukkonen, Lappeenranta University of Technology, Laboratory of Fiber and Paper Technology, Department of Chemical Engineering; Lappeenranta Finland
Antti Salminen, Lappeenranta University of Technology, Laser Processing Technology Research Group, Machine Technology Centre Turku Ltd.; Lappeenranta Finland
Presented at ICALEO 2011

Laser technology has been developed for processing of paper materials for 30 years. During its development, this technology has been confronted with difficulties in industrial application for paper industry. One of the main problems in laser cutting process is coloration of paper material during and after cutting.
Coloration of paper material can appear due to influence of several factors, such as heat and light, which can cause changes in chemical, physical, optical and mechanical properties of paper surface. It was assumed that energy required for successful laser cutting has to be pre-calculated in order to eliminate energy oversupply. A simple mathematical model found from literature was used for calculation of cutting energy. This model took into account such parameters as paper grade, sample thickness and specific heat of paper. Due to this, cutting energy can be calculated and estimated for paper samples of different composition and consequently with different properties.
Paper samples with different composition were laser cut with different parameters. Optical characteristics, such as yellowness, yellow-blue and green-red changes, of laser cut paper samples were measured during 12 day of storage time in controlled laboratory conditions. Paper material samples were cut by 2.7 kW Trumpf CO2 laser, with pressured air as cutting gas. This study was carried out in Lappeenranta University of Technology (Finland).