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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.

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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

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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

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Creasing and Folding arecritical steps in the
box forming process Dipl. Ing. Lukas Pescoller
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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
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The Creasing process

• fibre-fibre bonds between ply's are broken
• Some fibres are damaged
• Plastic deformation occurs
• Sheare, tension and compressing stresses arise
• Locally reduced bending stiffness
• Creased area hinge

Male Crease Rule
Card board
Crease Channel
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The creasing process
Source Hui Huang, KTH Stockholm
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The folding process
Spine
Delamination

• Folding uncreased paperboard results in cracks on
  the outside
• The ability to delaminate (fracture surface in
  parallel to the ply's) is an important property
  for folding
• Tensile stress arises on the outside ply (Spine)
• The inner ply's (Bead) are compressed and bulge
• Deformation and delamination takes place

Bead
Twin fold points
A crease is a double fold
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Deformation and delamination of creased card
board
Source Hui Huang, KTH Stockholm
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Analyze the Bead with CREASY
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The Bead width a delamination parameterthe
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
• Hard contact at the intersection between side and
  bead
• Extensive tension stress on spine
• Spine fracturing or crease end splitting

Extensive Tension
Insufficient delamination
Bead Binding
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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 the spine
• Fracturing and folding failure
• Is the creasing tool well centered and parallel
  to the crease channel?

One-sided crease
Max tensile stress
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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
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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 0.01mm
  resolution

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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

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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

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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

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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

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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

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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.

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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

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