Reduction of Broke in Paper Production
This project is an important part of a larger project of Mondi Business Paper, targeting on long term quality improvements of office papers and offset printing papers regarding dimensional stability.
It is necessary for every printing procedure, especially when it takes place in several steps and if it includes finishing procedure stages afterwards, that the paper has an exactly defined and if possible unchangeable shape. If such a paper starts to change this shape caused by external or internal forces, this has an impact on the quality of the printing process, the finishing process or in some cases even make those impossible. This is why the so-called dimensional stability of a paper sheet is such an important quality criteria for finishing customers, quality management, production, marketing, etc.
The complete concept of Mondi Business Paper first tried to make changes of the paper dimension precisely measurable because up to date methods of measurement have been too subjective and too little reproducible. This part was already worked out before this project started and was finalised by patenting and by ÖNORM standardisation of the LaBaCuS method, a laser-based curl scanning procedure.
As a second part a procedure was searched for that could put deformations of a paper sheet in direct relation to tensions of the paper web. This working step was implemented with the "Tension-Toy" software. With this we are capable to measure a deformed sheet of paper und to visualise the causal summed up tensions.
The main and final working step was to identify the influence factors causing tension during production, to quantify them, and to put them into a relation with sheet deformations. The wet end and especially the wire section of paper machines are problematic due to the impossibility to clearly visualise local flows there.
This problem and the solution of it have been the topic for this project that finally led to a development that allowed for a worldwide unique process to determine local flow patterns and their changes on a web that is used during a production process. This patented new technology utilises the detection of reflected light from the fibre suspension on the wire section of the paper machine. Changes in the flow pattern of particles are detected by video cameras, calculated and displayed in real time by newly developed software. In addition, areas of high turbulences are automatically marked as hot spots.
Dipl. Ing. Wolfgang C. Altenstrasser