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Printing and Bookbinding

Industrial Manufacturing - Machinery and Electronics · 製造分野 · Written by Tokutei Pass based on the official study texts; not copied verbatim.

Characteristics of the Four Major Printing Processes, Digital Printing, and Binding Styles

Printing processes are classified into four major types: 'Planographic (Offset) printing', 'Intaglio (Gravure) printing', 'Relief (Flexographic) printing', and 'Stencil (Screen) printing'. Plateless on-demand printing is called digital printing.

Offset printing uses the repulsion between water and oil, transferring (offsetting) ink from the plate cylinder onto a rubber blanket cylinder before pressing it onto paper; it is the most widely used method for books and commercial printing.

Gravure printing scrapes excess ink from recessed cells with a doctor blade and suits photographs and flexible packaging; flexographic printing uses elastic resin plates and an anilox roll and is widely used for corrugated cardboard.

Bookbinding styles include 'Perfect binding (wireless adhesive binding)' where gathered signatures are glued at the spine, 'Saddle stitching' where folded sheets are stapled through the center fold with wire, and hardcover 'Case binding'.

Characteristics of the Four Major Printing Processes, Digital Printing, and Binding Styles

Key points


  • (○ True) Offset printing is a planographic method using water-oil repulsion to transfer ink from the plate cylinder to paper via a rubber blanket cylinder.

  • (○ True) Gravure printing fills recessed cells with ink and wipes the surface with a doctor blade, while flexographic printing uses a flexible relief plate and an anilox roll.

  • (× False) Claiming that 'offset printing transfers ink directly from the plate cylinder to paper' or 'saddle stitching mills the spine and uses glue without wire staples' is FALSE.
WordMeaning
planographic plate (offset)
blanket cylinder
doctor blade
perfect binding (wireless adhesive)
saddle stitching

Prepress (DTP, Color Management, Halftone Dots, CTP, Paper Sizes, and Paper Grain)

Color printing reproduces colors by 'subtractive color mixing' using the four process inks Cyan (C), Magenta (M), Yellow (Y), and Black (K), whereas monitor screens display colors by 'additive color mixing' using Red (R), Green (G), and Blue (B) light.

Continuous tones in photographs are represented by varying the size of tiny 'halftone dots'; if the screen angles of the four colors are set improperly, an unwanted interference pattern called 'moiré' appears.

A system that images printing plates directly from digital data using a laser without intermediate film is called 'CTP (Computer To Plate)', and 'registration/trim marks (Tombo)' are placed around the sheet as references for color registration and cutting.

Standard Japanese base paper sizes include 'Kiku-ban (636×939 mm)' for A-series sizes and 'Shiroku-ban (788×1091 mm)' for B-series sizes; in bookbinding, paper must be cut and imposed so the 'paper grain (fiber direction)' runs parallel to the book spine so pages open smoothly without wavy warping.

Key points


  • (○ True) Process color printing uses CMYK subtractive mixing (darker as inks overlap), while monitors use RGB additive mixing (brighter as lights overlap).

  • (○ True) CTP outputs plates directly from digital data without film, and bookbinding requires the paper grain direction to be parallel to the spine.

  • (× False) Claiming that 'overlapping all CMYK inks produces pure white' or 'setting paper grain perpendicular to the spine makes books easier to open' is FALSE.
WordMeaning
subtractive color mixing
additive color mixing
halftone dot
color registration
paper grain (fiber direction)

Press Operations (Sheetfed Offset Press, Dampening Solution Control, and Print Defects)

At the feeder of a sheetfed offset press, air blasts and suction cups (suckers) separate sheets one by one, a 'double-sheet detector' prevents feeding two sheets together, and the 'front lay' and 'side lay' align each sheet accurately.

Dampening solution (fountain solution) is maintained at a weakly acidic pH of about 4.5–5.5; too little dampening water causes ink to adhere to non-image areas ('scumming'), while too much water causes 'over-emulsification' and low print density.

To prevent wet ink on delivered sheets from transferring onto the back of the sheet above ('set-off') or sticking sheets together ('blocking'), anti-set-off spray powder is applied and pile height is limited.

Paper dust or dried ink skin sticking to the plate or blanket causes donut-shaped white void spots called 'hickeys', while excessively high ink tack tearing fibers off the paper surface causes 'picking'.

Key points


  • (○ True) Dampening solution is kept weakly acidic (pH 4.5–5.5); insufficient water causes scumming, while excessive water causes over-emulsification.

  • (○ True) Spray powder prevents ink set-off, donut-shaped white spots are called 'hickeys', and surface tearing caused by high ink tack is called 'picking'.

  • (× False) Claiming that 'dampening water must be strongly alkaline above pH 11' or 'keeping the pressroom bone-dry in winter prevents static electricity' is FALSE.
WordMeaning
dampening solution (fountain solution)
scumming (non-image tinting)
over-emulsification
ink set-off
picking (paper surface tearing)

Post-Press Operations (Folding, Collating, Binding, Three-Knife Trimming, and Surface Finishing)

Large printed sheets are folded into signatures by a 'folding machine' and gathered in page order by a 'collator'. Pages bound in the wrong sequence are called 'miscollation (Ranchou)', and missing pages are called 'missing signatures/pages (Rakuchou)'.

Proper collation is verified visually by checking that the black 'collating marks (Sehyou)' printed on the fold spine of each signature form a neat stepped diagonal staircase pattern, supplemented by thickness sensors and cameras.

In a perfect binding line, the spine of the collated book block is roughened and notched by 'milling', coated with heated hot-melt adhesive or high-strength PUR adhesive, wrapped with a cover, and trimmed at the head, tail, and fore-edge by a 'three-knife trimmer'.

Book covers and packages undergo 'PP film lamination' or 'varnishing' for gloss and abrasion resistance, and folding cartons are die-cut and creased using a wooden flat die fitted with cutting rules and creasing rules ('Thomson die').

Post-Press Operations (Folding, Collating, Binding, Three-Knife Trimming, and Surface Finishing)

Key points


  • (○ True) Out-of-order pages are called 'Ranchou' and missing pages are called 'Rakuchou'; operators check that spine collating marks form a stepped staircase pattern.

  • (○ True) Perfect binding mills the spine so glue penetrates, attaches the cover, and trims the head, tail, and fore-edge on a three-knife trimmer.

  • (× False) Claiming that 'collating marks should all align in a single horizontal line' or 'a three-knife trimmer cuts off the glued spine itself' is FALSE.
WordMeaning
collating (gathering signatures)
miscollation (wrong page order)
missing pages / signature omission
collating mark (spine mark)
three-knife trimmer

Occupational Safety, Organic Solvent Control, and Environmental Protection in Printing & Binding

Plate cylinders, blanket cylinders and ink rollers rotate at high speed, so 'caught-in and entanglement accidents' are the primary hazard. Give signals and check the surroundings before starting; always stop the press (or use inching mode) before cleaning or clearing jams, and keep gloves from getting caught.

On paper guillotines (cutters), to prevent severe blade amputations, the 'two-hand control safety device' and 'photoelectric safety sensor (light curtain)' must never be bypassed, must be inspected before work, and each cutter must be operated by one person only.

When handling organic solvents such as roller washes or gravure inks, workers must run 'local exhaust ventilation', wear an 'organic gas respirator (with charcoal cartridges)' and chemical-resistant gloves, enforce no-open-flames rules, and check SDS and GHS labels.

For environmental protection, printing plants reduce volatile organic compound (VOC) emissions by using vegetable-oil inks and non-VOC washes, and sort trim waste and spoilage sheets ('Sonshi') free of prohibited contaminants for paper recycling.

Key points


  • (○ True) Always stop the press before clearing jams or wiping rollers, and never disable the two-hand buttons or light curtain on a paper cutter.

  • (○ True) When handling organic solvents, operate local exhaust ventilation and wear an organic gas respirator rather than a simple dust mask.

  • (× False) 'Wiping high-speed rotating rollers by hand with a cloth wrapped around your fingers' or 'taping down one button of a two-hand paper cutter' is a critical safety violation.
WordMeaning
caught-in / entanglement accident
two-hand control safety device
local exhaust ventilation
organic gas respirator
spoilage / waste paper (Sonshi)

Printing and Bookbinding Technology

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Official references