Finishing & Screen Printing

CREASY – the new optical measurement device to control creasing and folding quality in the box forming process

Tuesday 14. May 2013 - Cardboard is made up from bonded layers providing the material with stiffness enabling it to protect the goods properly and able to give the box a high quality finish

The Cardboard Box.
Cardboard is made up from bonded layers providing the material with stiffness enabling it to protect the goods properly and able to give the box a high quality finish
Because of its stiffness folding the cardboard will result in cracks and splitting on the outside of the box. To avoid cracks the stiffness of the cardboard is reduced along a defined line creating a bending crease, this is created with a crease rule pressing into a crease channel. The fibre?fibre bonds between the inner plies are broken. This causes the material itself to be delaminated and deformed showing a crease on the outer side of the box and a bead at the inner side. The bending stiffness now along the crease is significantly reduced and the crease behaves like a hinge.
In order to have full control about the creasing process, PERET has developed the CREASY, a hand held camera based measurement device. With a single key stroke the device calculates the dimensions and shape parameters of the Crease or Bead. The measured values can be collected in a statistics and reports can be created in PDF format.
CREASY is the tool to control the creasing process properly
Why is it important to analyze and control the crease and bead process and what can happen during creasing?
Before the CREASY was produced problems could only be detected after the boxes were formed and even sometimes only after the goods were already packed inside the boxes. As the box edges are stressed during packaging and transportation a high quality edge is a vital criterion for a quality box, most problems however can be predicted by analyzing the bead or crease and enabling the correction of the settings of the embosser.
Initially the card is folded to an angle between 90° and 180°, the bead rises up and the de? lamination of the inner layers takes place. On both ends of the bead there will be a folding point. In some cases the bead will not have been formed properly during the creasing either due to a partial de?lamination or the formation of an overlarge bead, this will result in extreme tension stress on the outside of the box, the consequence being cracks or splitting and the box becomes waste. The symmetry of the bead is also an important characteristic. Non symmetric creasing will obviously lead to non symmetric boxes and to run problems on the packaging line, and finally a low quality product both visually and in performance.
There are different sources for the problems in the creasing process. Even if settings are accurate with the creasing rule and creasing channel, there are abrasions to the cutting knives taking place. The operator typically changes the settings of the penetrating depth of the knife without realising the effects of the impact. This impact will lead to higher shear stress at the channel and reduce the life time of the tools.
Next there is the problems of bad register, rule – channel misalignment, tool?tool misalignment, crease rule dish or incorrect laser die?board cutting can be the source of a poorly formed or an asymmetric bead
Using the CREASY you can measure:
Critical dimensions and the symmetry of the crease before the pre?break and after the pre?break to optimize the settings of your embosser.
Check the creasing during the run of the press to predict quality problems in time. Calculate the job statistics at the end of the job.