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Course : Presswork Relief
- Flexo
Code: 502 |
Teaching Scheme
hrs/week |
Examination Scheme |
Theory |
Practical |
Theory
Marks |
Duration |
UT Marks |
Pr. Marks |
TW Marks |
3 |
6 |
80 |
3 hrs. |
20 |
30 |
20 |
Rationale:
This course includes the principles of working and basic
problems faced by letterpress & flexographic printers. It also
deals with online 7 offline finishing processes those can be carried
out using these principles. A study of Inks and Substrates used
in these processes is also covered.
SECTION
I - RELIEF
| Lesson
No 1: Printing machines
Theory.
|
Marks |
Hours |
1.1 |
Principal types of printing machines- construction, application,
Advantages and limitations, Problems in printing on different
machines
a) Inline
b) Stack
c) Common Impression cylinder
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1.2 |
Plate cylinder- construction, types- integral, demountable,
sleeves and magnetic, zero setting, plate mounting devices
and tapes.
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4 |
3 |
1.3 |
Impression cylinder- construction, loading method- pneumatic
or hydraulic. Impression (Tympan bar)- construction, tension
control, impression adjustment
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2 |
2 |
1.4 |
Hybrid presses, sheetfed presses and their application,
drying systems.
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2 |
2 |
1.5 |
Inline converting operation- slitting, laminating, punching,
coating
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4 |
3 |
1.6 |
Static electricity- causes for the generation of static
electricity, troubles created by static electricity and
methods used to eliminate static electricity.
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2 |
1 |
| Lesson
No 2: Ink metering system
Theory.
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Marks |
Hours |
2.1 |
Need of ink metering
i) Standard two roll inking system
ii) Two roll inking system with doctor blade
iii) Reverse angle doctor blade system
iv) Chambered doctor blade
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2.2 |
Fountain roll- formulation, types of roll coverings,
requirements and Properties, drive mechanism, storage
and quality control
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2 |
1 |
2.3 |
Anilox Roll
a) Specifications- cell wall, land, depth, opening, cell
count, cell volume, cell angle, depth to opening ratio
b) Different types of engravings on Anilox roll and methods
of engraving, Considerations for choosing proper anilox
roll.
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| Lesson
No 3: Inks for flexography
Theory.
|
Marks |
Hours |
3.1 |
General comparison of liquid flexographic ink with thick
(paste) offset or letterpress ink.
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1 |
1 |
3.2 |
Ingredients of flexographic ink- dyes, pigments, vehicles
and solvents with their types, properties and applications.
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3 |
2 |
3.3 |
Water based, solvent based and U.V. inks- composition,
properties, and areas of applications, advantages and
disadvantages.
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4 |
2 |
3.4 |
Different end use requirements of flexographic products-
ink adhesion, scratch, rub and block resistance, weather
resistance, gloss, coefficient of friction test, etc.
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4 |
2 |
| Lesson
No 4: Substrates
Theory.
|
Marks |
Hours |
4.1 |
Different types, properties
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2 |
2 |
4.2 |
Construction, end use
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2 |
2 |
4.3 |
Absorbent substrates- paper, paperboard and corrugated
board- printing characteristics and physical properties.
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-- |
1 |
4.4 |
Non-absorbent substrates- polyethylene, polyester, OPP,
BOPP, PVC, polystyrene, cellophane, metallized paper and
films and pressure sensitive film and substrates- printing
characteristics and physical properties.
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-- |
1 |
4.5 |
Surface Treatments- needs and theory behind surface treatment,
methods employed-corona, gas flame and chemical coating.
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2 |
1 |
4.6 |
Dispatch, Bar coding
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1 |
4.7 |
Environmental aspects.
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Practical
Introduction to different types of mounts, equipments and machines
of letterpress.
Introduction to different configurations of machines of letterpress
and flexo process.
Printing on various substrates using blocks & checking quality.
Printing the job using water based & solvent based inks for
flexo.
Duo tone printing
Printing multicolour jobs (line & halftone combination)
Reference books:
1) Flexography- Principles & Practices- FTA
2) Flexographic primer- Crouch- GATF
3) Letterpress printing- E.A.D.Hutchings
4) Letterpress printing (I & II)- Sharma
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