Industrial Printing Processes Flashcards
Printing processes names
Offset Lithography
Flexography
Screen Printing
Gravure
What is offset lithography, process?
Printing substrate either sheet fed or web roll fed
Printing plates produced using a laser which etches design on
Plates fitted to plate cylinder
Water rollers dampen plates
Ink is then applied using ink rollers (ink goes where water isn’t)
Substrate fed through, image is transferred
Repeated for each colour
Why does offset lithography work?
Water and ink do not mix
What is flexography?
Four colour process using water based inks
Anilox roller regulates thickness of ink
Print plates fitted to print cylinder
Impression roller applies pressure to transfer image
Web rolled
What is screen printing?
Substrate to be printed sits on machine base
Image is created as a stencil with gaps for ink to pass through
Different screen for each colour
A squeegee is used to force ink through the gaps
Advantages/disadvantages of offset lithography
High image quality
High volume prints
Long life printing plates
Quick and easy
Expensive setup
High running costs for small quantities
Only suitable for porous substrates
Advantages/disadvantages of flexography?
High print speed
Long run products
Wide variety of print surfaces
Low maintenance
Low cost of equipment
Cheapest
Printing plates expensive
Time consuming to alter
Large amount of substrate required
Advantages/disadvantages of screen printing?
Minimal setup costs
Simple and effective
Slow process with reasonably high cost per product
What is gravure?
Image acid etched onto metal cylinder
Cells are recessed (deeper means more colour)
Cells filled with ink, doctor blade wipes away excess
Substrate pressed against cylinder
Advantages/disadvantages of gravure?
Excellent print quality
Usable for CMYK printing
Not economic for small print runs
Fine text lettering not as sharp as other letter processes
Expensive setup costs for cylinders
What are the types of lamination
Layup lamination (GRP and CFRP)
lamination for wood
Encapsulation and surface coating (paper and boards)
Describe how laminating via encapsulation works
Desktop laminator heats up polymer sleeve causing it to encapsulate around the paper leaving a small border.
Polymer is typically a mix of PET and EVA
Describe how lamination via surface coating works
Liquid lamination can be applied with a roller or a spray and is used for things like signage to protect against moisture, dirt or UV light. Hot or cold process and creates things like menus and business cards
Film lamination is usually made from PP with an adhesive to make laminate stick to the paper. Laminate fed from roller and pressure is applied.
Describe embossing and how it works
Creates a raised design on surface of paper or card to give a tactile pleasing finish
Substrate sheet enclosed between male and female die and held under pressure until formed
Uses of embossing or debossing
Packaging
Greeting cards
Invitation cards
Describe the process of foil blocking
Heat applied to paper and then pressure is applied in the form of a pattern into the material over the foil
Heat causes the foil to stick to the material
Risks of foil blocking
Too much heat or pressure will cause foil to bubble and peel
Too little and it will not adhere
Uses of foil blocking
Enhance business cards
Company logos
Describe the UV varnishing process
UV is applied and cured with specific machinery to provide a high quality finish
Benefits and disadvantages of UV varnishing
High quality
Abrasion and chemical resistant
Smooth finish
Must be fully dried (time consuming)
Expensive
Describe spot varnishing
Varnish applied in specific areas to protect certain parts
Plate pressed into material applies the varnish
Benefits of using a varnish
Clear ink
Enhances finish
Some protection against dirt, fingerprints and water
Why flexography over Gravure for commercial printing?
Cheaper plates (rubber instead of laser engraved copper plates) meaning lower initial costs
Adjusting designs is easier due to ease of reproducing printing plates read for special discounts or other things that need to be added to design
