A Study on Usage of on-site Multi-monitoring System in Laser Processing of Paper Materials

Laser technology provides advantages for paper material processing as it is non-contact method and provides freedom of geometry and reliable technology for non-stop production. Reason for low utilization of lasers in paper manufacturing is lack of published research. This is main reason to study utilization of on-site multi-monitoring system (MMS) in characterization of interaction between laser beam and paper materials. Target of MMS is to be able to control processing of paper, but also to get better understanding of basic phenomena.Laser equipment used was TRUMPF TLF 2700 CO2 laser (wavelength 10.6 μm) with power range of 190-2500 W. MMS consisted of spectrometer, pyrometer and active illumination imaging system. This on-site study was carried out by treating dried kraft pulp (grammage of 67 g m-2) with different laser power levels, focal plane position settings and interaction times.It was concluded that spectrometer and pyrometer are best devices in MMS; set-up of them to laser process is easy, they detect data fast enough and analysis of data is easy afterwards. Active illumination imaging system is capable for capturing images of different phases of interaction but analysis of images is time-consuming. When active illumination imaging system is combined with spectrometer and pyrometer i.e. using of MMS, it reveals basic phenomena occurring during interaction. For example, it was noticed that holes created after laser exposure are formed gradually. Firstly, small hole is formed to interaction area and after that hole expands, until interaction is ended.