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Course : Press Work
Plano (Sheet-fed).
Code: 504 |
Teaching Scheme
hrs/week |
Examination Scheme |
Theory |
Practical |
Theory
Marks |
Duration |
UT Marks |
Pr. Marks |
TW Marks |
4 |
6 |
80 |
3 hrs. |
20 |
30 |
20 |
Rationale:
There are many different Offset presses in the market
today with many minute operational differences. The purpose of
this course is not to provide a general operational manual, but
to deal with the fundamental understanding that will enable the
student to run any offset duplicator or single and multi-colour
sheet-fed offset printing press after studying the manufacturer’s
operating manual.
This course covers the information necessary to run an offset
press and to give important information on press trouble-shooting
concerns also.
| Lesson
No 1: The offset printing machine (sheetfed)
Theory.
|
Marks |
Hours |
1.1 |
Construction & design, perfecting
|
3 |
3 |
1.2 |
Cylinder arrangement & working
|
3 |
2 |
| Lesson
No 2: Sheet handling & various types of sheet-feeding
mechanisms
|
Marks |
Hours |
2.1 |
Feed board- different parts and purpose
|
|
3 |
2.2 |
Sheet transport and control
|
4 |
3 |
2.3 |
Three points register system; machine tripping, lay setting
for different types of work.
|
4 |
4 |
| Lesson
No 3: Plate Dampening system
Theory.
|
Marks |
Hours |
3.1 |
Roller setting
|
2 |
2 |
3.2 |
Roller covering materials
|
2 |
2 |
3.3 |
Conventional & other dampening systems
|
4 |
5 |
3.4 |
Dampening solution, pH, conductivity, water hardness,
chilling tank
|
4 |
4 |
3.5 |
Maintenance
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-- |
-- |
| Lesson
No 4: Inking system
Theory.
|
Marks |
Hours |
4.1 |
Ink flow system & design – Sheet & web
|
2 |
3 |
4.2 |
Inking rollers, coverings, ink duct, ink duct, ink agitator,
roller setting and metering.
|
5 |
4 |
4.3 |
Inking systems- Pyramid, drum.
|
3 |
4 |
4.4 |
Roller wash up and Ink pumping system
|
2 |
1 |
| Lesson
No 5: The Printing Unit
Theory.
|
Marks |
Hours |
5.1 |
Plate cylinder
-Construction
-Undercut
-Cylinder gap
-Bearer contact and bearer clearance
-Plate clamps – Types, pin register system.
-Plate mounting
-Cylinder packing – Types
-Cylinder gears: comparison of spur and helical gears
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5.2 |
Blanket cylinder
Construction, undercut, cylinder gap, blanket mounting,
packing.
|
4 |
3 |
5.2a |
Types of Blanket(regular, U.V., glass built) –
requirements, characteristics- compressible, non-compressible
Blanket cleaning devices, handling, storage, maintenance,
thickness gauge, and low spot.
|
4 |
3 |
5.3 |
Impression cylinder
Construction, cyl.gap, packing, grippers, nip pressure.
|
4 |
2 |
5.4 |
Pressure Setting
Effect of change in packing (of P., B.and I. cyls.) on
printed image.
- Types of grippers – Tumbler, swing arm, rotary
feed, roll feed, gripper setting.
|
4 |
4 |
| Lesson
No 6: Sheet transfer and delivery
Theory.
|
Marks |
Hours |
6.1 |
Transfer cylinder, introduction to various drying systems,
anti-set-off spray, delivery system and setting.
|
6 |
5 |
| Lesson
No 7: Problems
Theory.
|
Marks |
Hours |
7.1 |
a) M/c and blanket related-
Misfeed, sheet jamming, front or side lay variation, creasing,
jogging.
Gear streaks, slurring, marking, doubling, uneven impression.
Blanket - Loss of sharpness, puncture(low spot), glazing,
mis-register, tightness of blanket.
b) Ink- Mottling, dot gain, set–off, hickeys, ghosting,
chalking, emulsification, piling, tinting, trapping, plate-blinding,
scum
Dampening – scum, streak, white spots etc.
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6 |
5 |
7.2 |
Paper-Characteristics for Sheet/web - fed, handling and
conditioning, storage.
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2 |
2 |
7.3 |
Ink –Characteristics for Sheet/web- fed, drying
properties.
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2 |
2 |
7.4 |
Use od Quality control devices
Printing of dot gain slur gauge, star target, test forme
|
2 |
3 |
7.5 |
Advancements in Sheet-fed machines.
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-- |
Practical
1. Feeder setting for various stocks
2. Mounting of plate with packing
3. Mounting of blanket with packing
4. Gripper setting of impression cylinder
5. Setting of dampening roller
6. Preparation of foundation solution
7. Cleaning & washing of dampeners
8. Setting of inking rollers
9. Cleaning & wash up
10. Setting – joggers, skeleton wheels, delivery anti set-off
spray
11. Make ready operations for multicolor printing line and halftone
printing
12. Color sequence alterations
13. Color mixing & preparation of shade
14. Preventive maintenance
15. Checking effect of keeping rollers of same diameter
16. Study of mechanism of impression lever, inking, dampening
lever, feed board devices
17. Study of ink water balance.
Reference books:
Litho Offset
press operating |
Latham, GATF |
Solving Sheet fed offset
problems |
GATF staff |
Litho printing |
Blue printing - Faux |
Machine printing |
Durrant |
Printing Technology |
Adams, Faux – Delmar publication |
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