The document discusses the function and mechanics of doctor blades in anilox ink metering, emphasizing their role in controlling ink transfer to printing plates. It explains the differences between forward and reverse doctoring, detailing the impact of blade properties such as stiffness, thickness, and angles on ink metering efficiency. Additionally, it covers best practices for selecting and maintaining doctor blades to optimize print quality and minimize wear on anilox rollers.

1. Doctor Blade Metering
The What and How in
Anilox Ink Metering.
Tony Donato
Product Development Engineer
Harper Corporation of America
tdonato@harperimage.com

2. FIRST 4.0
From Section 21.4 Ink Metering System:
“ The function of the ink metering system is to control the
amount of ink being transferred onto the printing plate.”
From Section 21.4.1 Doctor Blades:
“ The primary function of the doctor blade is to uniformly
remove ink from the surface of the anilox without
damaging the anilox.”
Ink Metering

3. Doctor Blade Metering
OUTLINE:
• The difference between forward and reverse doctoring.
• Ink metering terms: Set-Angle, Contact Angle, blade
deflection, sheen, back-doctoring, blade loading pressure,
blade alignment and many others.
• The importance of blade stiffness to metering.
• How blade thickness affects metering.
• Why are there different blade tips.

4. Forward and Reverse Metering
Simplest Examples
http://www.autogeek.net/windshield-ice-scraper.html
Reverse metering shears off
the unwanted material.
Windshield Ice ScraperWindshield Wiper Blades
Forward wiping pushes
the unwanted material.

5. Forward Metering
Blade points in the
direction of rotation.
Pushes the surface ink back into the pan.
Traditionally used in Gravure
on Chrome Rollers
Ink is pushed
back to the pan

6. Forward Metering
Pluses:
• Ideal where roll diameter
changes with the jobs.
• Less wear to rollers
being metered.
• Helps to lubricate blade.
Minuses:
• Works best with low
viscosity inks.
• Potential for speed
limitations due to
hydraulic lift.
• Blade position and
stiffness dependant.
Application Importance:
• Needs blade angle and location adjustability.
• Important to pick the right blade thickness, tip and
back-up blade combination.

7. Forward Metering Angle Relationships
A Distance blade tip to Cylinder Vertical Center Line
B Distance of blade tip to Cylinder Horizontal Center line
C Circumvential Distance Nip point to Blade Tip
D Elevator (Up & Down) adjustment for table assembly
E Slide (In and Out) adjustment blade holder
F Table Tilt (Pivot) adjustment for table assembly
G Set angle for blade to Cylinder without loading deflection.
H Contact Angle of blade tip with deflection
90
0
90
0
15
90
0
90
0
75
74.92°ø 6.00"
58.72°
54.11°
75.05°
A
Impression
Roll
Gravure
Cylinder
F
C
D
E
Reference line (Tangent) Set angle
Protractor Angle Finder
Angle Finder gives angles relevant
to earth.
G
H
B
Typical Contact Angles are:
Packaging Gravure 40° to 65°
Publication Gravure 50° to 70°
Coating & Wall Covering 40° to 55°
Dimensions related
to Center line of
Gravure Cylinder

8. Reverse Metering
“Reverse Metering” shears the ink off the Anilox surface.
Anilox
Ceramic anilox rollers allow the use of reverse metering.
Single Blade Enclosed Blade Chamber

9. Reverse Metering
Pluses:
• Meters the ink surface
cleaner than forward.
• No hydraulic lift.
• Meters viscous inks.
Minuses:
• Blade holders or chambers
have fixed set angles.
• Fixed roller diameter.
• Blade wear changes angle.
• Shears large pigments
• Pearlescent
• Metallic's
Application Importance:
• Needs hard surfaces.

10. Set Angle
90.00°
Anilox
Anilox
Reverse Metering
Single Blade
• Ink Pan Only
• Ink Pan w/ Fountain Roll
Chamber
• Two Blades
• Meter & Containment
• End Seals & Pump.
Blade Angles are fixed by holder & Chamber supplier

11. Metering Terms
90.00°
Set Angle
Anilox
Center Line.
Reference Line
From Anilox Center
To point of
Blade Contact
Tangent Line
Perpendicular to
Reference line
The “Set Angle” is the Chamber/Holder
Machined Angle without any load.
Doctor Blade
Anilox

12. Contact Angle
Worn Area
Contact
Patch
Anilox
Deflected Doctor Blade
Metering Terms
The “Contact Angle” is worn at the tip and is
the result of all forces acting on the blade.
FIRST
recommends
“Contact Angle”
should be
between 25-40
degrees.
Lower angles Print Dirty,
Higher Angles Chatter

13. Metering Terms
Blade
Extention
Blade
Extention
Blade
Tip to Tip
Blade clamping
seat area
With Inking
Chambers the
metering and
containment
blade can be on
either the top or
bottom, all
depends on
chamber
placement on the
anilox.
Anilox

14. Dull Sheen Indicating Good Metering
Metering Terms

15. Metering Terms
Chamber opened up from the outside deck #7
Top of picture is bottom (6 O’clock) of chamber
Drips on doctor blade is back doctoring of ink
White drops tinting is high speed “Ink Misting.”

16. • Containment Blades can trap contaminates under it.
• Keep Containment blades Clean.
Small Dried Ink Chunks
Containing Metal
Particles
Plastic or Composite
Blades with
Embedded Particles
Dried ink on the back (outside) of the blades
Back doctoring does more than just waste ink.

17. 90.00°
Containment
Set Angle
Set Angle
45.00°
Metering Terms
Anilox
Chamber
Meter
Blade
Containment
Blade
Unloaded blade
is at the highest
angle.
High speed presses
are trending at
lowering the
containment set angle.
Chambers do
not have to
have the same
angles for both
blades

18. 90.00°
90.00°
37.47°
13.20°
Anilox
Contact Angles decrease with increased loading pressure!
Containment
Contact Angle
.
These are
good angles
for high
speeds.
Metering Terms
Lower containment
blade angles help to
reduce back doctoring.
Chamber has
.031" (.79mm)
of loading

19. Blade holder alignment needs to be part of press maintenance.
Metering Terms
28.48°
90.01°
5.11°
90.00°
Anilox
Metering Contact Angle
Containment “Contact Angle”
Chamber has
.0625” (1.6mm)
of loading
Doctor
blades are
spring steel
and the more
they are
loaded the
harder they
push into the
anilox roller.

20. Extreme low
containment
angles will
trap dried ink
and
contaminates
Ink magnets
and filters are
required for
high speed
presses
3.52°
90.00°
18.42°
Anilox
Metering Contact Angle
Containment Contact Angle
Chamber has
.125” (3.2mm)
of loading
Metering Terms
Extreme loading will result in burrs created on the blade edge.

21. Anilox rotation remains the same on CI press
Outside decks 6 to 10 Inside decks 1 to 5
Back doctoring drips off
chamber into pan
Back doctoring puddles behind blade
and slings off the end of the anilox
Containment
Blade
Containment
Blade

22. Doctor Blade Mechanical
Specifications and Properties:
Mechanical Properties: Affect loading
pressure, blade life and anilox wear.
•Tensile strength (spring like quality) ,
• Hardness
• Wear resistance.
• Chemical resistance.
Physical Attributes: Affect the printing
performance.
• Thickness and width tolerances, flatness,
surface finishes and camber (curvature
also called edge straightness)
Deflected doctor blade
and released it laid flat!

23. Doctor Blade Mechanical Property:
Deflected a piece of steel banding stock.
Blade must deflect and re-flatten, it cannot take a set!
Banding stock unsuitable for a number of reasons!

24. Doctor Blade Mechanical
Specifications and Properties:
• The initial wiping between the blade and roller are effected
by variations in blade camber, flatness and width.
• All of the mechanical and physical properties affect the
amount of loading force needed to cleanly meter the anilox.
• In addition, the blade mounting, holder/chamber physical
dimensions/condition & mounting mechanism must be kept in
good working order for the doctor blade to properly work.
A´A
Blades must be parallel to each other, & tip to tip distance the same.

25. Blade Mechanics Simplified
1"
d
t
Load
w
Looking at the mathematics and
mechanics a doctor blade is a “beam”
fixed on one end and loaded on the other.
“w” is load in lbs/linear inch
“d” is deflection at the tip (inches)
“1” is the extension of blade
“E” Modulus of elasticity 30,000,000lbs for
steel.
“I” Moment of inertia for the blade cross
section.
w x 1³
3 x E x I
d = (1)

26. 1³ (blade ext)__
t³
Blade Mechanics Simplified
1"
d
t
Load
w
t³
12
Moment of Inertia I =
t = blade thickness
We substitute equation (2) into (1)
d =
____w x 1³____
3 x E x (t³ / 12)
(3)
(2)
Set w = to 1lbs/ linear inch and assume
steel “E” for the blade material we get:
d =
____1___________
(3 x 30,000,000/ 12)
x (4)

27. Blade Mechanics Simplified
STILL AWAKE LAST SLIDE WITH MATH!!!!
The exponents in equation (4) show the
cube factor.
Example leaving a blade in too long:
(.750/.625)³ = 1.73 times stiffer
Example replace .006” with 0.008: (.008/.006)³= 2.24 times.
If the stiffer blade was left in until it was 1/8” shorter:
Then: 1.73 (shorting) x 2.24 (thickening) = 3.87 times stiffer
CHANGES IN THICKNESS AND EXTENSION CAN EFFECT
ANILOX WEAR.

28. Blade Mechanics Tested
Experiment:
Used .006” & .008” doctor blades and two different widths
to get ½” extension and a 1” extension. Applied two
separate weights first 4.75lbs and second 7.2lbs statically
and measured the deflection with a dial indicator.

29. Blade Mechanics Tested

30. Blade Mechanics Tested
Unloaded
Loaded

31. Blade
Thickness
Blade
Extension
Blade
Length
Weigh
used
Load per
linear inch
Deflection
.006” 0.500” 6.25” 4.75lbs 0.38lbs/in 0.029”
.008” 0.500” 6.25” 4.75lbs 0.38lbs/in 0.012”
.006” 0.500” 6.25” 7.2lbs 0.58lbs/in 0.049”
.008” 0.500” 6.25” 7.2lbs 0.58lbs/in 0.021”
.006 1.000” 6.25” 4.75lbs 0.38lbs/in 0.132”
.008” 1.000” 6.25” 4.75lbs 0.38lbs/in 0.082”
.006” 1.000” 6.25” 7.2lbs 0.58lbs/in 0.162”
.008” 1.000” 6.25” 7.2lbs 0.58lbs/in 0.146”
Blade Mechanics Tested

32. Doctor Blade Loading
What to expect from what we have learned so far!
• Typically the highest angle is the set-angle.
• As the loading pressure increases the “Contact-Angle”
decreases.
• Loading pressure can lower the contact angle beyond the
point of clean metering. (Below 26°)
• As a blade wears it narrows and the contact angle increases.
• Between loading and wearing the blade contact point moves
away from the center line.

33. Overloading the blades changes wear.
Excessive pressure may result in creating wire like slivers.
Anilox Roll
Chamber
Lamella Tip
Clamp Bar
Tip not
contacting roll
Wear Patch
Is behind Tip
Radius Tip
Over-Loaded
Blades can
Cause Scoring !!
Do Not
do this to your
Doctor Blades !!

34. Top blade has .217” worn off came from white deck!
Steel Slivers created from overloading.
Slivers form
break off and get
loaded between
blade and anilox
damaging
surface.

35. 90.00°
18.42°
90.00°
48.17°
0.23 in
1.25 in
Chamber is engaged .125" (3.2mm)
Blade was 1-3/8” and
after the chamber is
loaded to 1/8” the blade
can wear to a width 1-1/4”
The contact
patch shifts
with chamber
loading and
blade wear.
Chamber has
.125” (3.2mm)
of loading
Doctor Blade Loading Observations

36. 90.00°
18.42°
90.00°
48.17°
18.62°
22.96°
Chamber is engaged .125" (3.2mm)
Chamber has
.125” (3.2mm)
of loading
Doctor Blade Loading Observations
As the blade narrows the
point of contact on the
anilox moves increasing
the set angle.

37. Doctor Blade Material Selection
• Carbon Steels:
• Blue Carbon, White (Bright) Carbon
• Wear (Premium) Alloy Steels:
•Tool Steel Alloys:
•Laser Hardened Tips
• Stainless Steels:
• Coated Steel or Stainless:
• Ceramic, or Plated
• Plastics:
• UHMW, Acetal, Polyester, Proprietary compounds.
• Composite:
• Fiberglass, Carbon Fiber
Work with your blade supplier.
Each material has its best application!

38. 45.00° 20.00°
•Square
• Round Radius
• Beveled
• 45
• 15 to 20
• 5 or less
• Stepped (Lamella)
• Single Step
• Double Step
Blade Tips (Profile)

39. Blade Tips
Typical tip applications:
• Square Tip
• Plastic Containment blades.
• Back-up Steel Blades
• Round (Radius) Tip
• Metal Metering WW w/Chamber w/Sunday Drive
• Beveled 45°
• UHMW Plastic
• Beveled 15 or 20°
• Metal on NW (seats quickly)
• Composites and stiffer plastics
• Lamella (stepped)
• Where the tip needs to thin and body stiffer.
• Double stepped
• Where a stiff blade is needed w/ narrow contact.

40. Blade Thickness
Thickness considerations:
• Blade Material dependant
• Plastics & Composites thicker than metals
• Application dependant
• Corrosive ink or coating or environment.
• Ink pigmentations or material (ex. TiO² white)
• Metering or Containment
• Anilox Geometry
• 30 & 60°
• 45° Quad
• Channeled
• Trihelical
• Anilox Screen
• Process & solids
• Coatings and adhesives

41. Blade Optimization work with your supplier
• Periodically have a used blade analysis
– Check contact angle over 3 spots across web
– amount worn 3 spots
• The Used Blade can tell you:
– Loading degrees (pressure)
– Blade alignment to anilox
– Chamber condition
• Set shop practices.
– Blade Changing schedules.
– Loading pressures
– Mounting training

42. Worn Doctor
Blade showing
engraving lines
Anilox Engraving post intersections leave lines in doctor
blades contacting edge
25,400µ/”
Line to lineµ
25,400 µ/in
18 µ
18 Microns
Anilox effects wear pattern.
Equation to calculate
the CPI of an Anilox
from a worn blade
CPI = x Cos of Engr ∟
= 705 CPI 60° Angle of Engravingx 0.5

43. • Doctor Blade contact angle does effect blade vibration.
• Doctor blades can change the surface smoothness of the
anilox.
• Loading pressure reduces the blade angle.
• Blade wear can increase the contact angle.
• Thicker doctor blades increase the blade angle because
they deflect less.
• Thicker doctor blades increase wear area spreading load.
• Best metering contact angles between 26°to 38°.
• Above 40°contact angle can result in chatter.
• 4° to 5°of loading deflection is helpful for metering
above a 1000 fpm.
Metering Review

44. • The empty anilox cells bring air back into the chamber.
• Know what your set angles are.
• Lower containment contact angles can reduce back
doctoring.
• Containment blades can wear faster on full coverage.
• Use caution when handling used doctor blades. They
are sharp.
• Your suppliers they are your best resources.
• Doctor blades should shear off the surface ink leaving
only the ink in the Anilox cells.
• The abrasiveness of the ink itself needs to be
considered.
• Change blades when changing cpi.
• Remove ink contaminants with filters and magnets.
Metering Review

45. Be Observant of the Anilox Metering
• Anilox properly metered “Dull Sheen”
• Looks shinny excessive “surface ink”
– Excessive loading pressure.
– Chamber or holder at bottom of adjustment.
• Shinny streaks “nicks in blade”
• Sheen varies side to side:
– Mounting and or alignment issue.
• Variation in density across web:
– Uneven loading pressure.
– Mounting and or alignment issue.

46. Doctor Blade Review
Work with your blade supplier.
• Specified by material, thickness and tip.
• There is a proper blade for each application.
• Blades affect print quality and Anilox life.
• Blade Mounting is very important.
• Important: Holder/Chamber alignment to Anilox
• Blade loading pressure critical.
• Record Doctor Blade Information: Create a log
and track issues and concerns
• Used blades are sharp are a razor blade.
• Have used blades analyzed periodically.

47. Doctor Blade Metering
The What and How in Anilox Ink Metering.
QUESTIONS?

48. Doctor Blade Metering
The What and How in Anilox Ink Metering.
Tony Donato
Product Development Engineer
Harper Corporation of America
tdonato@harperimage.com
THANK YOU FOR ATTENDING!