Heatset Offset Lithography

1. Heatset Offset
Lithography

2. Heatset Web Offset
Heatset offset is very versatile printing method both from
product and paper point of view
• Products
• magazines, catalogues, direct mail, newspapers, inserts,
brochures, illustrated books and manuals
• Papers
• WFC, MWC, LWC, MFC, SC, UWF, newsprint
• Grammages from 35 ~150 gsm
Heatset printing has global market of ~80 billion €
Paper consumption over 8 million tons of paper in Western
Europe (2008)

3. Reality check
Global advertising is down ~10% and in magazines ~18%
Deliveries of coated mechanical reels were down ~20% in 2009
compared to 2008
Low operating rates are reflected on prices, which are also going down
Customers are shifting to lower qualities and lower grammages
• How to maintain printed quality?
Paper manufacturers are turning every stone to cut cost in paper
manufacturing
• Runnability issues will increase

4. Basic design of heatset press
siliconization unit
reelstand dryer
printing units
infeed chill rolls
folder
Web widths: ~50 - 280 cm
Web speed: ~4 - 15 m/s
Web tension: ~600 - 800 N/m
Drying (web temp): ~110 - 140 °C
Folding: usually on-line

5. Press layouts
Majority of presses (>80%) are long grain
Benefits of long grain
• more variety in folding
• last fold in grain direction in A4 production
• important for perfect binding
Benefits of short grain
• ribbon folder higher productivity
• page flexibility (height of page)

6. Heatset presses - different designs
Additional units additional colour
varnishing unit (offset varnish)
• extra colours
• varnishing
Twin webs
• productivity
• versatility
Sheet cutter
• for heavier grammages
• for off-line varnishing
On-line finishing Twin web
• direct mail

7. Heatset web offset printing unit
KBA Compacta
618 Blanket to blanket nip
Ink system
• high number of rollers to ensure thin and even ink
layer
• 3-4 ink form rollers to ensure even ink transfer to plate
Fountain system
• 3-4 rollers
• water form roller in contact with ink rollers and plate
• ensures fast emulsification
ink duct
Courtesy of KBA

8. Heatset dryer
Web delay in the dryer is ~1 s
dryer length is determined by the press speed (10 m/s 10 m)
Dryer has multiple modules
Hot air from the nozzles carries the web through the dryer
Exhaust air is either circulated back or is let to atmosphere through treatment
(e.g. afterburner)
Together with solvent also moisture is evaporated
coated grades: ~4-5% 1-2%
uncoated grades: ~5-8% 2-3%
~240°C ~200°C ~150°C
~120-140°C

9. Chill rolls and Siliconization
Chill rolls Siliconization
• Thermoplastic ink binder is in • Usually one roller rotating
soft form after the dryer in pan
• chill rolls cools down the web and • to protect printed area from
solidifies the binder (better rub smearing
resistance) • also functions as a
• Steel cylinders (3 - 6) with cold remoistening device
water pumped through
• Web tension has to be high
enough to ensure good contact

10. Folders
Usually former folders
• former fold followed by 1-2 jaw folds
With high pagination the use of ribbon folding is increasing
• web is slitted into ribbons (typical in gravure)
• also choice for short-grain presses
Courtesy of KBA

11. Folding: 16-page, long-grain
Former
fold
Jaw fold
880 mm Chopper/
jaw fold
630 mm