A detailed
analysis is made in this problem solving guide
for common problems faced in Packaging Flexo
press room. A brief description is given of
each dilemma alongwith the possible causes
and remedies. If you still have more questions
, please use our Enquiry section to ask our experts.
Streaks?
| CAUSE
|
REMEDY
|
| 1. Foreign
Particle under blade |
- Reduce blade pressure under
blade
- Install ink filters in ink
system
- Install magnets in ink system
- Change the doctor blade
|
| 2. Cut
in doctor blade |
- Install ink filters
- Change doctor the blade
- Check roughness of anilox
roller
- Check new blade tip for damage
(if small, polish with #600
emery paper)
|
| 3.Abrasive
ink and/or solvents |
- Use STAINLESS STEEL doctor
blade
- Use different pigments
- Check pH balance of ink (water-based)
|
Uneven Ink Metering ?
| CAUSE
|
REMEDY
|
| 1. Blades
is wavy |
- Clean the doctor blade holder
and remount blade
- Check blade holder for damage
- Tighten bolts from center
out alternating sides
- Replace missing bolts if any
- Provide even tensioning of
bolts on holder by using a torque
wrench
- Make sure blade is not too
long for holder
- Check end seal placement
|
| 2. Alignment |
- ensure centerline of chamber
is parallel to center line of
anilox roller
- Make sure both the blades
in the chamber contact the anilox
roller at the same time
- Ensure uniform extension from
holder
|
| 3.
Vibration |
- Blade chatter- blade angle
too steep
- Gear vibration from press
- Bounce from printing plate,
fix the plate uniformly
|
Excessive Anilox Wear ?
| CAUSE
|
REMEDY
|
| 1. Extra
pressure on doctor blade |
- Look for the reasons why excessive
pressure is needed and correct
- Install mechanical units
to ensure the chamber does not
contact anilox roller
- Metal fillings (silvers) from
the blade tip. (Excessive pressure
causes wiping by back of blade
rather than the tip. The blade
tip becomes thin and wears through,
releasing silvers in inking
system. This can damage the
anilox.)
|
| 2. Contact
area too large |
- Use correct width doctor
blade (check with holder manufacturer
for correct size)
- Use reduced thickness blade
tip
- Reduced blade thickness if
using straight steel
- Check blade angles
|
| 3.
Poor steel quality |
- Analyse steel for purity
- Check for excessive roughness
on blade tip ( use fine polishing
paper to correct)
- Try alternative blade materials
(check with CONVERTECH to correctly
match blade to application)
|
Excessive Ink Film Thickness ?
| CAUSE
|
REMEDY
|
| 1.Contact
area too large for cell count
|
- Use pre-ground lamella blade
to reduce contact area
- Incorrect blade angle
- Use thinner blades
|
| 2.Cell
volume or cell count of anilox not
matched to line screen count of
plate |
- Guideline: Cell count should
be 4-5 times that of plate
|
Leaking Chamber ?
| CAUSE
|
REMEDY
|
| 1. Incorrect
chamber alignment |
- Ensure chamber is parallel
to anilox roller and both top
and bottom blades are contacting
anilox roller at the same time
|
| 2.Incorrect
end seals or incorrect setting |
- Check with holder manufacturer
for correct material and
dimensions
- Check blade settings (ensure
blade extension is correct to
match cut on end seal)
|
| 3.Blade
is wavy |
- Improper seating of blade
in holder allows ink to escape
holder
- Poor condition of holder
- Missing or worn bolts in holder
assembly
|
| 4.Re-doctoring
of ink from containment blade |
- Reduce excessive blade pressure
- Correct ink viscosity
- Incorrect containment blade
for press holder or anilox
|
