Why control of creasing is important Customer expectations

Why control of creasing is important Customer expectations Customer expect you to produce high quality packages with no cracks and no splitting on folding end points Customer expect you to provide uniform packaging boxes Customer expect the shape of the box to represent the quality of the product inside the box. 1

Why control of creasing is important Quality department expectations Documented quality across multiple production sites Possibility to define and visualize quality standards and tolerances Increasing quality 2

Why control of creasing is important Manufacturing manager expectations Long live time of creasing and cutting tools No runability problems on the packaging line Minimum waste because of un-usable boxes Full controlled processes Anticipate potential problems before going into production Detailed information about potential sources of a problem 3

4

Creasing and Folding are critical steps in the box forming process Dipl. Ing. Lukas Pescoller

Paperboard is … A thick, single or multiply paper based material. composed of several layers of pulp fibres with preferred orientation bonded by starch or adhesive material Bending stiffness is one of the most important mechanical properties for paperboard packaging bending stiffness is mainly attributed to the outer ply's with higher Density [Source: Hui Huang, KTH Stockholm] 6

The Creasing process fibre-fibre bonds between ply's are broken Some fibres are damaged Plastic deformation occurs Male Crease Rule Sheare, tension and compressing stresses arise Locally reduced bending stiffness Creased area = hinge Card board Crease Channel 7

The creasing process [Source: Hui Huang, KTH Stockholm] 8

The folding process: Folding uncreased paperboard results in cracks on the outside Spine Delamination The ability to delaminate (fracture surface in parallel to the ply's) is an important property for folding Bead Tensile stress arises on the outside ply (Spine) The inner ply's (Bead) are compressed and bulge Deformation and delamination takes place A crease is a double fold 9 Twin fold points

Deformation and delamination of creased card board: [Source: Hui Huang, KTH Stockholm] 10

Analyze the Bead with CREASY 11

The Bead width – a delamination parameter the distance between the twin folding points Problems with wide bead: Un-sharp folding points Insufficient internal delamination and inflexible bead Low flexibility – bead gets crushed during folding Extensive Tension Insufficient delamination Hard contact at the intersection between side and bead Extensive tension stress on spine Spine fracturing or crease end splitting Bead Binding 12

The folding point sharpness defines the symmetry of the bead Non symmetric folding points Off-center folding non uniform boxes Extensive stress in an arrow area of One-sided crease the spine Fracturing and folding failure Is the creasing tool well centered and parallel to the crease channel? Max tensile stress 13

Reasons for assymetric bead theory Parallel crease close to each other limitation in material stretch Competition in drawing the material Each crease is poorly formed With asymmetric bead Asymmetric internal delamination The resistance to crease formation grows fast after a critical distance practice 14

Reasons for assymetric bead Rule – channel misalignment Tool to tool misalignment (tolerance mismatch) Crease rule dish Incorrect laser die-board cutting vertically Have a look at the adjustment proposal in 0. 01 mm resolution: 15

The bead height as an indicator for the penetration depth The knife (position/setting) changes the penetration depth of the rule changing the tension forces which can result into die-cut edge chipping or flaking, or breaking the cardboard material or faster erosion the upper corners of the crease channel Cutting knife abrasion leads to resetting of the knife position 16

Crease cross section analysis with CREASY Measure bead Rotate sample by 180° Measure crease The software will overlay the two images showing the result in terms of a card board cross section 17

Compare crease before and after first break The first break defines the final location of the twin folding points The first break defines the final symmetry of the folding The first break shows problems with cracks, fracturing and folding failures 22. 03. 13 18

Control the final product box quality with CREASY The box angle should be as sharp as possible The box angle should be as symmetric as possible The angle between the folding panels should be close to 90° 19

Control the setup process with CREASY The bead shape and size will differ depending on the orientation of fibres and crease channel The bead can be optimized by setting the creasing tools properly The optimisation can be measured with CREASY and a statistic can be created A PDF Report can be created with CREASY 20

Folding box manufactuing control with CREASY Measure the beads of same orientation with CREASY and use the statistics to collect measurement data CREASY does support 4 orientations of beads CREASY creates a PDF Report per folding box CREASY offers a statistic for the entire job. 21

Why control of creasing is important No customer will accept cracks and splitting on folded packaging products No customer will accept non-uniform packaging boxes The paper structures and folding behaviour vary with fibre lengths, fibre content, fibre orientation Coatings, bond between coating and paper Printed ink, varnish Heat to dry the ink of the print sheet reduces flexibility Environment – humidity in the pressroom The cutting & creasing process itself has variations Help to avoid runability problems on the packaging line Help to avoid waste because of un-usable boxes 22

Thank you… See what happens Understand why it happens actions Take corrective 23