Influence of Paperboard Structure and Processing Conditions on Forming of Complex Paperboard Structures By Magnus Östlund,* Svetlana Borodulina and Sören Östlund BiMaC Innovation, Department of Solid Mechanics, KTH (Royal Institute of Technology), Stockholm, Sweden Experiments were made with a laboratory apparatus for forming paper sheets into double‐curved structures. The purpose was to learn more about the design criteria for forming of paper materials into complex shapes. The influence of forming parameters such as moisture and temperature was studied, and the performance of some common pulps as raw materials for the paper sheets was evaluated. Papers made from short hardwood fibres performed worse than papers from other pulps, and the method of moisture application was more important than the amount of moisture that was applied. Copyright © 2011 John Wiley & Sons, Ltd. Received 24 August 2010; Revised 2 February 2011; Accepted 23 February 2011 KEY WORDS: formability; paperboard; pulp; moisture; packaging INTRODUCTION The ability to use light materials in packages is very important nowadays. For various types of packages, the producer tries to decrease the cost, and the demand grows for new types of packaging materials. The demand for ecologically sustainable materials to make packages is also increasing. Thus, paper materials should be able to increase their market share in the packaging business in the foreseeable future. One market where plastics still have an advantage is aesthetically attractive packages with complex shapes. This research is aimed at increasing the formability of paper and paperboard to levels comparable with the formability of plastics. Methods for forming of double‐curved paper structures tend to fall under one of two categories. The first type is pulp being sprayed onto a mould of the desired shape, whereas the second type is forming of paper or paperboard produced in a traditional fashion. The resulting mechanical properties are much better for traditional paperboard than for the pulp sprayed structures. Hence, better double‐curved packages may be obtained by forming of paperboard if only the damage from the forming can be limited. The forming of traditionally manufactured paper and paperboard is explored in this paper. Paperboard formed in such a fashion can be found in common grocery stores in the form of trays for food intended to be cooked in its package and as plates for eating from. These products have been deep drawn. Deep drawing is a process developed for sheet metal and consists of pressing a male die into the sheet until it stops against a female die, leaving an imprint on the sheet. Although the products are common, there are very few literatures published about deep drawing of paperboard. It would seem that all research behind the appearance of these products were done by the industry, who keeps the knowledge confidential. Deep drawing as a process may have its limitations for the forming of complex‐shaped double‐curved paper packages such as a bottle. Commercial trays are also typically creased, detracting from the aesthetic value of the double‐curved structures and suggesting that only very basic research has been done at all. * Correspondence to: M. Östlund, BiMaC Innovation, Department of Solid Mechanics, KTH (Royal Institute of Technology), Stockholm, Sweden. E-mail: magost@kth.se PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2011; 24: 331–341 Published online 21 June 2011 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pts.942 Copyright © 2011 John Wiley & Sons, Ltd.