Technical FAQ's

Please find below the most common error patterns during the manufacturing process with possible causes and solutions...

Problem Cause Solution
Film breaks/tears before heatingmaterial too cold (< 5°C); especially PVdCacclimatisation of the material for min 24h. During winter please make sure the inner part of the reel has room temperature as well
  bad edge trimcheck film for roughness and replace if necessary
Problem Cause Solution
Bubblesair between material and toolsandblast tool to allow air to escape
  humidity on tool, therefore water drops on filmincrease tooling temperature
  contaminants on toolclean tool
  material too hotreduce temperature
  uneven temperature distributionoptimize temperature distribution
Wrinklesmaterial too hotreduce temperature
  uneven warmingcheck temperature of tool
  stretch of material too strongreduce temperature
Problem Cause Solution
Blister adheres on toolPVdC sticksreduce PVdC temperature and increase opposite side
  tool too hotreduce temperature
  edges of moulding too sharpreplace or adjust moulding
  material too hotreduce temperature
Wrinkling in blistertool or material too hotuse cooling or reduce temperature
  bad tooling constructionoptimize or replace tooling
Missing contactleaking forming toolcheck position
Material clustering in transverse directiontemperature of material too highreduce temperature
  surface of tool too smoothsandblast surface
  vacuum too slowincrease vacuum speed
  wrong assembly of vacuum holesoptimize/change assembly
Material tears during thermoformingmaterial too hotreduce temperature
  material not thick enoughmeasure thickness and if necessary switch to other film
  forming tool too coldreduce cooling
  material too coldincrease temperature
  compressed air/vacuum too earlyadjust timing
  pressure/speed of stamp too highadjust pressure/speed of stamp
Material breaks/tears on the bottom of the cavitymaterial too hotreduce temperature
  very deep cavityuse a forming plug or thicker material
  inclusions in cavitycontact manufacturer of material
  uneven material thicknessthickness profile
Holes in blistercontaminated materialcheck material specification
  vacuum holes too bigminimize vacuum holes
  material temperature too lowincrease temperature
  clock cycle too shortincrease clock cycle
  ventilation does not work properly when plug moves into the cavitycheck ventilation
  material sticks on toolchange material / use mould with Teflon® coated surface
  irregular heatingcheck heating cystem and change defect parts of heating system
  vacuum / pressure timing not optimizedcdjust vacuum and pressure onset / duration
Part deforms during demouldingmaterial ejected too hotincrease cooling time
  tool too hotreduce tool temperature (cooling)
Parts in the corners too thinmaterial temperature too highreduce temperature
  radius of the mould too smallincrease radius
  tool too hotreduce temperature
  flanks too flatredesign part
Bad formingmaterial temperature too lowincrease temperature
  tool too coldreduce cooling
  to short cycle timeoptimise / extend cycle time
  vacuum not sufficientincrease vacuum openings and control vacuum feed
  insufficient sealing of toolcheck sealing ring; check flatness of plates
  air trapped between cavity and plasticcheck number and arrangement of vacuum holes
  forming pressure too lowincrease pressure
Marks on bottom of formed partmaterial temperature too highreduce temperature
  insufficient pre-heatingextend / optimise pre-heat zone
  insufficient exhaust holesenlarge or increase number of holes
  insufficient vacuum formingincrease vacuum
Irregular edge width of the formed areamaterial temperature too highreduce temperature
  material shrinkage is too highreplace material
  pre-stretching is too earlyadjust rhythm
  forming table goes up too quicklyadjust speed
  vacuum forming too earlyadjust vacuum forming
  material temperature too highreduce temperature
  forming tool is not sealedcheck flatness
Surface of formed areacontaminated materialreplace material
  contact heating plates are dirtyclean or replace plates
  punch has surface defectsclean/polish surface or replace punch
  forming part is dirtyclean forming part
  material has inclusionscheck inclusions and eventually contact supplier
  punch surface is roughclean/polish surface
Problem Cause Solution
Uneven sealingtemperatur/pressure/time not optimialreduce line speed by half and check again
    measure thickness profile of film
Lidfoil can be pealed off easily and completelytemperature much too lowreduce line speed by half and check again
    increase temperature by 20°C
  missing or wrong lacquer on alu foiltest sealing in laboratory
  PVC film was under heater too long (>20 min.)advance film (approx. 0.5 meter) and try again
Problem Cause Solution
Slitting dust/angel hairsslitting gap too bigadjust or replace
  knives not sharpsharpen or replace
  slittting depth not enoughincrease slitting depth

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