40
BASIC COURSE IN PRINTING TECHNOLOGY

The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Embed Size (px)

Citation preview

Page 1: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

BASIC COURSE IN PRINTING TECHNOLOGY

Page 2: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

The main Printing process

• Letter press• Offset Lithography• Gravure• Flexography• Screen Printing• Other Reprographic process

Page 3: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Letter Press

• Letter Press is a relief process• The image is reversed and it is non readable• The process uses metal type which is hand set or

machine set • Pictures are made from blocks made of photo

engraving.• Inks are tacky and drying by absorption, oxidation• Used for printing bill books, wedding cards of

smaller number say upto 1000 impressions

Page 4: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 5: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Offset Lithography• It is a plano graphic process• Uses the principle of oil and water do not mix• The image and the non image are in the same

plane.• There are three basic cylinders

– Plate cylinder (Image carrier – readable)– Blanket cylinder (carries the image) – Impression cylinder (transfers Printing)

• The inks are tacky and it is Thixotrophic in nature• Can Print on relatively rougher surfaces• The inks dry by absorption and by oxidation and

polymerisation

Page 6: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Offset Lithography

• Most commonly used press where the number of impressions are any thing from 1000 – 50 ,000 copies.

• Sheet fed - cartons, folders, magazine covers• Web offset – magazines , news papers etc• Low preparatory costs when compared to other

process• Operation skill required is very high

Page 7: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 8: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Gravure

• Intaglio process – the image area is recessed• The gravure cylinder where the image is etched

( image carrier) is immersed in a pool of liquid inks

• The inks are carried by the cylinder and the excess ink is wiped by the doctor blade

• The impression from a rubber roll makes the ink to transfer to the substrate through capillary action

• The image is non readable • Mostly economical where the run length is very

high

Page 9: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 10: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Gravure

• Most common application are cigarette, flexible laminates, currency notes etc.

• The initial cylinder costs are very high which is justified only if the run length is high

• Requires very smooth surface as the image is direct contact with the substrate

• Also good compressibility ensures better printing• Produces a continuous tone effect in the image

Page 11: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Flexography

• A form of relief Printing uses rubber or resilient plastic plates ( photo polymer plates)

• The inking system uses a special annilox roller immersed in liquid inks

• Inks dry by evaporation• Uses water based inks and is most friendly for

food packing applications• For large runs of liquid packaging, getting

popularity in publishing abroad

Page 12: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Screen printing

• It is a stencil process• Can print on any surface • Uses high tack paste inks• Used for very short run job as the initial

cost is less• Used for printing visiting cards, textile

printing etc.

Page 13: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Printing a job

• The ad agency or the customer prepares a rough layout or dummy

• The customer gives the copy for reproduction which can be text matter, line drawings, photographs etc

• The customer prepares a mechanical layouts which shows the position and others which is called art work

• The type setting is done

Page 14: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Photographic Originals

Quality and Productivity

Litho – Offset Print Production

Page 15: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Artists’ Originals

Quality and Productivity

Litho – Offset Print Production

Page 16: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Graphic Originals

050

100

1stQtr

3rdQtr

Quality and Productivity

Litho – Offset Print Production

Page 17: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

1234567890`~!@#$%^&*()-_=+;:’”,<.>/?

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

1234567890`~!@#$%^&*()-_=+;:’”,<.>/?

Text

Quality and Productivity

Litho – Offset Print Production

Page 18: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Digital Originals

Quality and Productivity

Litho – Offset Print Production

Page 19: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Printing a job … contd

• The photographs, pictures which are continuous are scanned.

• The text and pictures are combined as per the art work

• After these they are assembled to make a negative

• Depending on the plates, negative or positive is exposed with the plate to give the Plate for printing

Page 20: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Printing a job … contd• The plate is developed after exposure and is

mounted on the printing machine• The printing takes place with the help of the

ink and the image from the plates• After printing post printing operations like

cutting , varnishing, punching are done

Page 21: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Colour theory

• Additive primaries – Blue , green, red – The combination these three coloured lights give white light. The principle used in TVs, computer monitors etc

• Subtractive primaries – Maganta, cyan, yellow –The combination othese three pigments/dyes give black – Used in printing, painting etc

Page 22: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Human Vision

Colour Measurement

Page 23: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Additive Colours

Page 24: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

RGB RG GB G RB R B

Colour MonitorsRGB

K

Colour Measurement

Page 25: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Colour theory

4 Colour printing – A picture is scanned and four positives of cyan , yellow , maganta , black are taken

Cyan – Red filter

Maganta – Green filter

Yellow – Blue filter

Black printer – Under colour removal

Page 26: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

The process of printing

• The printing process is done through dots. • The tonal gradation is achieved through

varying the size of the dots but the number of dots remain same.

• The number of dots in a square area determine the resolution of the picture

• The half tone process is done through screens in printing.

Page 27: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 28: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 29: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 30: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process
Page 31: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper Properties and their relation to Printing

• Caliper/Bulk/Density– Determines the pressure required to get good

Print– Uniformity in caliper to minimise variation

across the sheet– Bulk/density determines the print reproduction

in direct contact process– Creasing and folding property

Page 32: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper Properties and their relation to Printing

• Smoothness/Roughness– Determines the ink transfer and dot

reproduction on the surface– Final Print gloss and Varnish Gloss– Dot Gain

Page 33: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Impact of smoothness and Coating

art paper

glossy inks

newsprint

coldset

Page 34: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Dot gain

Dot sizeon print

Dot size onscanners display

Dot Gain

Quality and Productivity

Litho – Offset Print Production

Page 35: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

ideal

art paperglossy inks

newsprint

dirty base

density of original

printdensity

white base

limit

Tone Reproduction(Print Density)

Quality and Productivity

Litho – Offset Print Production

Page 36: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper Properties

• Colour– Expressed as Whiteness, Brightness and L, a, b

values. – Print colour reproduction (shade Matching)

Page 37: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper Properties

• Moisture and Dimensional Stability– Runnability in web feed process– Blistering in Heat set web offset– Register control in sheet fed offset– Folding and Creasing

Page 38: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper properties

• Tensile Strength– Runnability in web feed process– Pack formation in flexible laminates

• Pick strength– Ability to take high tack inks– Ability to run at faster speeds

Page 39: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Paper Properties

• Water Absorbency– Ink drying– Dimensional stability

• Ink Absorbency– Post Print gloss– Pick strength– Ink drying

Page 40: The main Printing process Letter press Offset Lithography Gravure Flexography Screen Printing Other Reprographic process

Thank you