Multiscale Statistical Process Control of Paper Surface Profiles

Abstract

Paper surface plays a key role in paper quality. Accurate paper surface profiles contain the fundamental raw information of the surface for a wide range of length-scales, to which different aspects of the paper quality are connected. With the goal of exploring the availability of such paper surface data obtained through a mechanical stylus profilometer, we present in this paper an approach for setting up a Multiscale SPC procedure that monitors simultaneously two key quality surface phenomena that develop at different scales: roughness and waviness. The raw profiles, after adequate processing using a multiscale framework based on wavelets, give rise to quantities that can be effectively used to monitor these two phenomena in a simple and integrated way, and therefore be implemented in practice for quality control purposes. The effectiveness of the proposed procedure is assessed by simulation as well as through a pilot study involving real paper surface profiles.

Key Words:

• Multiscale analysis
• paper surface
• process monitoring and diagnosis
• statistical process control
• wavelets

Additional information

Notes on contributors

Marco S. Reis

Marco S. Reis is a Teaching Assistant and PhD Student at the Department of Chemical Engineering of the University of Coimbra, Portugal. He has worked several years in the Product Development Department of a major Portuguese pulp and paper company and his current research interests are centred around the areas of Process Systems Engineering, Applied Statistics and Chemometrics. He is an elected member of ENBIS Council and author or co-author of several articles and conference presentations in the fields of Process Systems Engineering, Applied Statistics and Chemometrics.

Pedro M. Saraiva

Pedro M. Saraiva is an Associate Professor in the Department of Chemical Engineering and Pro-Rector of the University of Coimbra, Portugal. His interests are in the areas of Process Systems Engineering and Quality Management. He is a senior member of ASQ and received from this society the Feigenbaum Award (1998). He is the Founder and Partner of QUAL-Quality Management Consulting Firm, author and co-author of several books, articles and conference presentations in the fields of Process Systems Engineering and Quality Management.