1 Blurred or sharpness problem: Unsharp printing means blurred reproduction of lines or lettering.
Probable Cause
Possible Solution
Pad
Too soft.
Use a harder pad.
Wrong shape.
Use a different shape.
Cliche’
Inaccurate etch.
make a new cliche'.
Etching is too deep.
Etch a new cliche' with less depth.
Wrong type of cliche'.
Use the suitable cliche' type(e.g. steel in place of polymer).
Wrong type of screen.
Test a new cliche' with a different screen.
Ink
Ink is too thick.
Add more thinner.
Ink is too thin.
Reduce the amount of thinner.
Slow drying.
Use a faster drying thinner or cliche' pause.
Material
Dirty surface.
Pre-clean.
Rough, grainy surface.
Switch over to other material, if possible, or try a harder pad.
Large differences in height.
Use special shaped pads and pad mounting devices.
Printing near edges.
Fixtures must support the pad to prevent slippage.
Other
Work piece fixtures are not stable enough.High speed causes pad vibration.
Make new fixtures.Decrease speed. If necessary, pause at front position
before releasing the ink film to avoid vibrations of the pad during printing.
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2 Ink does not meet adhesion requirements This problem frequently occurs because the material of the product is
unknown or the wrong type of ink is used.
Probable Cause
Possible Solution
Pad
Too much silicone on surface.
Clean new pads with alcohol beforeuse.
Cliche’
Etched too deep.
Remake cliche' deeper.
Ink
Wrong type of ink.
Use the suitable ink according to thetechnical data sheet.
Bi-Component?
Use bi-component ink with hardener.
Incorrect ratio of ink to hardener.
Remix ink with correct ratio by weighing ink and hardener.
Material
Dirty surface.
Preclean with alcohol.
Other
No/insufficient pretreatment.
Check pretreatment procedure. If necessary, repeat.
Required cure time is not met.
Leave parts for longer period of time before testing.
No/insufficient after-treatment.
Use heat tunnel and in some situations flame parts.
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3 Small pinholes are apparent If they're large and consistently in the same place, check the pad and
cliche' for damage. Replace if necessary.
Probable Cause
Possible Solution
Pad
Surface is damaged.
Replace pad or adjust so that damaged area won't interfere with image.
Pad is too flat.
Use pointed shape pad.
Too soft.
Use a harder pad.
Cliche’
Bad etching due to error or dust during exposure stage.
Remake.
Ink
Ink is too Thick.
Add more thinner.
Material
Rough surface.
Use a firmer pad.
Parts dirty.
Clean.
Other
Ink contaminated with silicone or oils.
Replace with new ink.
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4 Colors transferring between pads on multi-color jobs. In fast multicolor printing sequences a subsequent pad can remove a previous
color.
This happens most often in larger print motifs on substrates not etched by the
thinner. This usually occurs in connection with multi-station conveyors or turntables
when using slow drying inks. This problem can be eliminated by initiating print
and cliche' pauses.
Probable Cause
Possible Solution
Pad
Porous, worn surface.
Replace pad.
Cliche’
Etching is too deep.
Etch a new cliche' with less depth.
Wrong percentage and LPI of screen.
Test a new cliche' with a different screen. (higher DPI screen for smaller
areas & detail)
Ink
Ink has too much thinner.
Add more pure ink to cup or inkwell.
Ink is drying too slow.
Use a faster drying thinner, blow air, or use pad delays/ pauses to give
inks time to dry.
Material
Very smooth surface. Substrates which cannot be etched by the thinner
(e.g., glass) are especially problematic.
Use hot/ cool air blown onto part between colors, or use pauses before
printing.
Substrates contaminated with oils.
Clean parts prior to printing.
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5 Uneven ink thickness Usually occurs with larger areas of ink coverage.
Probable Cause
Possible Solution
Pad
Wrong shape.
Use a different shape.
Cliche’
Wrong cliche' type.
Use steel cliche' to prevent ink "scooping".
Wrong etching depth.
Make a new cliche' controlling depth.
Wrong type of screen.
Test a new cliche' with a different screen.
Wrong orientation.
Turn long lines at an angle.
Ink
Too thin.
Reduce the amount of thinner.
Too thick.
Add more thinner.
Insufficient mixing of ink andadditives.
Mix the ink thoroughly before puttingit into the ink tray or cup.
Material
Odd shaped surface.
Use suitable pad.
Other
Doktor blade too soft.
Use firmer doktor blade or convert to inkcup system.
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6 Distortion in printed image Distortion usually occurs when a printing on deep or curved surfaces.
Probable Cause
Possible Solution
Pad
Wrong shape.
Use a different shape.
Too soft or too hard.
Use different hardness.
Image too close to pad edge.
Move or replace pad.
Cliche’
Etched too deep.
Coupled with thin ink, the smudging caused isoften mistaken for distortion.
Ink
Etched too deep.
Causes smudging (see above)
Material
Moves or collapses.
usare supporti speciali o tamponi
Other
Unsuitable work piece fixtures.
Modify the fixtures to achieve supporton all positions of the product.
Fixtures move.
Check fixtures.
Printing on angle.
Change fixture angle.
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7 Opacity of ink is poor This is usually a direct result of printing on dark substrates with a
single print. In these situations a second "hit" will usually bring
the image up to a desired opacity level. Otherwise, a background print in white,
or sometimes silver, will lay down a sufficient level of ink to make a brighter
image.
Probable Cause
Possible Solution
Pad
Porous and rough.
Replace pad.
Too flat and soft causing insufficient inkrelease.
Use a firmermore pointed pad.
Cliche’
Etching depth is too low.
Etch a deeper cliche'.
Wrong type of screen.
Test a new cliche' with a different screen.
Wrong type of cliche'.
Use a different type of cliche'.
Ink
Ink too thin.
Thicken ink.
Ink not transferring completely.
Use print pause or air blower to partially dryink for proper release.
Material
Image not brilliant enough due to darkness of parts.
Use double hit to lay down additional layer.
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8 Smudged image This occurs when ink is too thin or pad slips during print. Slippage
of pad during printing can be caused by too hard a pad, poor fixtures, angle of
part in fixture, or excess pad pressure.
Probable Cause
Possible Solution
Pad
Too hard.
Use a softer pad.
Too small in relation to the image.
Use a larger pad.
Prints over edges.
Adjust the pad stroke and/or use fixture with more support.
Cliche’
Depth too deep.
Make a new cliche'.
Wrong type of cliche', may need screen.
Test a new cliche' with a screen or use a different type of screen.
Ink
Too thin.
Add pure ink to thicken.
Slow drying.
Use a faster thinner.
Material
Very uneven surface.
Use special shaped pads or adjust pad positions.
Other
Fixtures are unstable.
Remake.
Work piece fixtures are not stable enough.
Remake.
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9 Mis-registration of colors multi-color print
Probable Cause
Possible Solution
Pad
Pads are not mounted correctly.
Adjust pads to pick up images in the exact same place.
Unequal shapes.
Use equally shaped pads.
Different hardnesses.
Use pads of the same durometer.
Cliche’
Images are not in registration.
Re-register artwork and etch new cliché's.
Ink
Image spreads more in one color than in another.
Correct ink viscosity to prevent incorrect dot gain.
Material
Parts collapse (e.g. plastic bottles).
Use a more supportive fixture.
Other
Work piece fixtures are not stable enough.
Control. Make new fixtures if necessary.
Conveyor, shuttle or turntable moveinaccurately.
Establish more accurate control of indexing.
Fixtures are insufficiently attached.
Fasten fixture screws.
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10 Image appears blotchy A dry appearance or voids in the print is usually caused by ink which
had dried in the image area of the cliche'.
Probable Cause
Possible Solution
Pad
Too flat.
Use a more pointed shape pad.
Porous, worn pad.
Replace pad.
Cliche’
Etching depth is too shallow.
Make a new cliche' with deeper etch.
Wrong type of etch.
Make new cliche' with screened areas.
Ink
Too thick.
Add thinner.
Ink dried in etching.
Clean the cliche' with thinner.
Material
Contaminated with oils.
Clean with alcohol.
Other
Machine speed too low.
Increase speed of the machine.
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11 Ink sticks to pad surface If the pad picks up the image cleanly but does not drop-off entire image
during print stroke, voids will appear in image.
Probable Cause
Possible Solution
Pad
Too soft.
Use a harder pad.
Wrong shape.
Use a more pointed shape.
Roughened porous surface.
Replace with a new pad.
Cliche’
Etch is too shallow.
Etch a deeper cliche' if ink is drying on pad.
Etch is too deep.
Etch a new cliche' with less depth, or use cliche' pause to allow ink
time to partially dry on cliche'.
Ink
Dried on the pad.
Use retarder or more thinner.
Too wet on the pad -does not film well.
Use a faster thinner or pause on the print stroke.
Material
Dirty surface (grease, oil, releaseagents, hand sweat).
Preclean. Depending on the grade ofdirtiness, with alcohol, if necessary.Wear
gloves during printing.
Other
Room temperature is too high.
The room temperature is best at 64-68 °F.
Pad speed too low.
Increase speed - in the case of ink drying on the pad.
Pad speed too high.
Use pause on print stroke in case of ink too wet to allow more drying
time, or use cool/hotair.
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12 Hairs on edges of image This can be caused by a static charge in the part, but can also be due
to other factors such as pad shape and improper ink viscosity.
Probable Cause
Possible Solution
Pad
Too flat.
Use a more pointed shape.
Cliche’
Etch is too deep.
Remake a cliche' with less depth.
Wrong type of screening or no screen.
Use a different screen.
Ink
Too thick.
Add more thinner.
Ink is drying too slow.
Use a high speed thinner.
Material
Static charge.
Use a de-ionizer or increase humidity in shop.
Other
Air moisture is too low.
Increase air moisture up to 60-80%.
Cycle time is too high.
Reduce printing speed.
Pad pressure too high forcing ink outward.
Decrease pressure.
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13 Fine lines begin to close up This problem usually occurs in reverse images where copy has dropped
out of the artwork.
Probable Cause
Possible Solution
Pad
Too hard.
Use a softer pad.
Roughened porous surface.
Use a new pad.
Cliche’
Etch depth is too deep.
Make a new cliche' with lower etching depth.or use pause to allow ink
set/drying time in cliche'.
First exposure of plate-making process is too long.
Make new cliche' with lower exposure times.
Wrong type of etch.
Use a different type of cliche' with screened image area.
Ink
Ink too thin.
Reduce the amount of thinner.
Too slow; ink smears out.
Use a faster thinner, or pause above cliche'.
Material
Too smooth (e.g. glass)
Clean thoroughly, to aid in "catching" the ink.
Other
Pad stroke is adjusted too high. Causes ink tobe forced out of etched
areas.
PAD PRINTING MACHINERY
