6.10.2020
Traditionally, the development of new paperboard-based packaging and problem solving of quality issues has been carried out through collaborations in the packaging chain. From the manufacturing of paperboard-based packaging materials, conversion and filling and then evaluation of the result. This means many iteration loops in the packaging chain before a new concept is approved or the quality deficiencies are corrected. In recent years, the development of computer simulation methods of paperboard materials and its interaction in the converting process and filling machines has contributed to the reduction of the number of iterations loops necessary in the development of new packaging systems. The goal is to use computer-based models of packaging material to simulate all stages of the packaging chain - to reduce cost, time to market, to obtain zero quality losses, as well as minimize environmental impact.
Results from collaborations between Universities and companies
The development of computer-based models of packaging material is an ongoing and successful collaboration between industry, institutes and universities. Examples of activities, that I have been involved in, are PhD projects at the Division of Solid Mechanics, Lund University. Rotation creasing, studied by Eric Borgqvist [1], is an example where creasing in a production-like environment are studied, see Figure 1(A). In [1] Borgqvist developed a simulation model which was calibrated against paperboard and used the model to simulate rotational creasing. In Figure 1(B) the shear stresses in the out-of-the-plane direction are shown. Damage in the paperboard occurs due to out-of-the-plane shearing induced by the creasing operation. This type of simulation study can be used to understand how the properties of the crease tool and/or paperboard properties affect damage in the material when folded into a package. Figure 2 shows a fold in the MD and CD direction of paperboard, where the development of damage can be studied in detail.
After a paperboard-based packaging material is produced with folding lines, the material is e.g. transported to a dairy, which pack a dairy liquid product into a package using a filling machine. In the forming process, the packaging material is formed and sealed into a package, as shown in Figure 3. Figure 3 is taken from [3] where Kristofer Robertsson simulated the forming process using solid shells with the paperboard model developed for creasing and folding analysis in [1] and [2]. Simulation studies of the forming process can be used to understand how forming, filling and sealing operations interact with the folding lines and paperboard properties.
Research result transfer from the university to industry
An important part of the effective cooperation between universities and industry is the transfer of knowledge between partners and the implementation of research results to a production environment in the industry. For this, cooperation is also needed between software providers of simulation software and the industry to get stable and consistent implementation of a model that works well together with existing functions. Calibration of the computer models to different paperboards and packaging materials and maintenance of the material database is a key to achieving good support for production. In conclusion, computer-based models have the possibility to be used in all stages of the packaging chain - to reduce cost, time to market, to obtain zero quality losses, as well as minimize environmental impact.
References
[1] Eric Borgqvist et. al., Composite Structures, Volume 126, 2015, Pages 184-195, ISSN 0263-8223, https://doi.org/10.1016/j.compstruct.2015.02.067.
[2] Kristoffer Robertsson et. al., Packaging Technology and Science, Volume: 31, Issue: 8, Pages: 557-566, First published: 27 June 2018, http://dx.doi.org.ludwig.lub.lu.se/10.1002/pts.2383
[3] Eric Borgqvist et. al., Packaging Technology and Science, Volume: 29, Issue: 7, Pages: 397-414, First published: 03 May 2016, https://doi-org.ludwig.lub.lu.se/10.1002/pts.2218
Writer:
Johan Tryding
Senior Material Specialist at Tetra Pak
Adjunct professor at Solid Mechanics, Lund University