Proper mounting and usage of Sureprint
Doctor Blades on the printing press
ensures that you get longer life and
excellent wiping action from the Doctor Blade.
This section explains proper mounting of Doctor
Blades on the machine.
Preparation for mounting the Sureprint
Doctor Blades
- The Blade Holder must be clean at all
times. No ink sedimentation between the
blade and the Blade Holder should be permitted.
- Ensure that the Blade fits firmly and
without undulations at all times.
- Mount the Doctor Blade in the Blade Holder
and ensure that it fits uniformly. The lamella
should face upwards and be visible.
- Always tighten the screws from the middle
outwards. The distance between the Doctor
Blade tip and the Blade Holder should be
about 10-25 mm.
- The support blade must be clean and uniform
and should be mounted on top of the Doctor
Blade as shown in the figure below. To permit
flexibility and proper lubrication, the
thickness of the support blade should be
between 0.3-0.4 mm.
The distance between the support blade tip
and the Doctor Blade tip should be between
3-5 mm. To give more flexibility at the Doctor
Blade ends the edges of the Support Blade
should be tapered (as shown below), this will
increase the working life of the printing
cylinder as well as the Doctor Blade.
Contact Angle and
Pressure
The
doctor blade contact angle is one of the most
important points in order to achieve a brilliant
and clean printing result.
If the angle is set to the ideal 60 to 70
degrees, the contact area between the blade
and the cylinder will be minimal.
Having a minimal contact width will automatically
allow the operator to use a minimum of doctor
blade pressure. The lower pressure will allow
for a longer doctor blade life as well as
much less cylinder wear.
Adjust the Blade Holder for uniform setting.
Gently increase the pressure till a good wipe
is obtained.
Rounding the cylinder ends (Radius)
The cylinder edges should be rounded with
a 3-5mm radius to minimize doctor blade wear
as it oscillates on the face of the cylinder.
Miscellaneous Suggestions
- To obtain a good wipe, the roughness of
the cylinder after plating, should be between
0.3-0.5 microns for films/ foils, and 0.5-0.8
microns for paper. This will also help the
lubrication of the blade.
- Inspect the Lamella (Blade Tip) for any
accumulation of ink or dirt. If such accumulation
occurs, clean with pencil styled sharpened
bit of wood, applying light pressure.
- If the same blade is being used for various
substrates, before changeover, clean the
Blade tip with fine abrasive paper # 600.
<<
Back
