| Blister adheres on tool | PVdC sticks | reduce PVdC temperature and increase opposite side |
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| tool too hot | reduce temperature |
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| edges of moulding too sharp | replace or adjust moulding |
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| material too hot | reduce temperature |
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| Wrinkling in blister | tool or material too hot | use cooling or reduce temperature |
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| bad tooling construction | optimize or replace tooling |
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| Missing contact | leaking forming tool | check position |
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| Material clustering in transverse direction | temperature of material too high | reduce temperature |
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| surface of tool too smooth | sandblast surface |
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| vacuum too slow | increase vacuum speed |
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| wrong assembly of vacuum holes | optimize/change assembly |
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| Material tears during thermoforming | material too hot | reduce temperature |
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| material not thick enough | measure thickness and if necessary switch to other film |
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| forming tool too cold | reduce cooling |
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| material too cold | increase temperature |
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| compressed air/vacuum too early | adjust timing |
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| pressure/speed of stamp too high | adjust pressure/speed of stamp |
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| Material breaks/tears on the bottom of the cavity | material too hot | reduce temperature |
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| very deep cavity | use a forming plug or thicker material |
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| inclusions in cavity | contact manufacturer of material |
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| uneven material thickness | thickness profile |
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| Holes in blister | contaminated material | check material specification |
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| vacuum holes too big | minimize vacuum holes |
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| material temperature too low | increase temperature |
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| clock cycle too short | increase clock cycle |
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| ventilation does not work properly when plug moves into the cavity | check ventilation |
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| material sticks on tool | change material / use mould with Teflon® coated surface |
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| irregular heating | check heating cystem and change defect parts of heating system |
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| vacuum / pressure timing not optimized | cdjust vacuum and pressure onset / duration |
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| Part deforms during demoulding | material ejected too hot | increase cooling time |
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| tool too hot | reduce tool temperature (cooling) |
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| Parts in the corners too thin | material temperature too high | reduce temperature |
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| radius of the mould too small | increase radius |
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| tool too hot | reduce temperature |
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| flanks too flat | redesign part |
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| Bad forming | material temperature too low | increase temperature |
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| tool too cold | reduce cooling |
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| to short cycle time | optimise / extend cycle time |
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| vacuum not sufficient | increase vacuum openings and control vacuum feed |
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| insufficient sealing of tool | check sealing ring; check flatness of plates |
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| air trapped between cavity and plastic | check number and arrangement of vacuum holes |
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| forming pressure too low | increase pressure |
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| Marks on bottom of formed part | material temperature too high | reduce temperature |
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| insufficient pre-heating | extend / optimise pre-heat zone |
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| insufficient exhaust holes | enlarge or increase number of holes |
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| insufficient vacuum forming | increase vacuum |
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| Irregular edge width of the formed area | material temperature too high | reduce temperature |
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| material shrinkage is too high | replace material |
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| pre-stretching is too early | adjust rhythm |
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| forming table goes up too quickly | adjust speed |
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| vacuum forming too early | adjust vacuum forming |
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| material temperature too high | reduce temperature |
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| forming tool is not sealed | check flatness |
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| Surface of formed area | contaminated material | replace material |
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| contact heating plates are dirty | clean or replace plates |
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| punch has surface defects | clean/polish surface or replace punch |
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| forming part is dirty | clean forming part |
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| material has inclusions | check inclusions and eventually contact supplier |
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| punch surface is rough | clean/polish surface |
