Binding A printing job is not complete until it is converted to a finished marketable product and delivered. These are the function of postpress: binding, finishing and distribution. I would like to tell you about binding
The work required to convert printed sheets or webs into books, magazines, catalogs and folders is called binding. There are generally five steps in pamphlet binding: - scoring - folding - gathering (collating)
- stitching, cutting and trimming Scoring. Folding is made easier by first scoring of heavyweight or cover paper. A score is a crease in a sheet of paper. Folding. There are 2 kinds of folds: parallel and right angle. In parallel folding, each fold is parallel to the other. A right angle fold is 2 or more folds, with each fold at right angles to the preceding.
Collating. Collating can be done by hand or machine, depending on the size of the job. Stitching. The booklet is placed on a saddle beneath a mechanical stitching head, and staples are forced through the spine of the booklet. This type of binding is the simplest and most inexpensive.
Cutting and trimming. Computer controlled guillotine cutters used to cut labels, paper and etc. trimming is usually done with 3 knives in a single cycle. Digital Digital printing is a combination of digital imaging and digital press. Digital imaging has already almost completely replaced conventional prepress. It has created an intermediate type of printing process with digital prepress and conventional press. Digital imaging has made possible the filmless imaging. There are 3 types of filmless digital imaging processes: computer-to-plate, computer-to-plate-on-press and computer to print.
Computer-to-plate create images directly on printing plates for conventional printing. This systems almost always used for gravure and flexography, and sometimes for lithography. Computer-to-print create images directly on plateless presses. This systems, like ion or electron charge deposition, electrophotography, ink-jet systems and magnetography, now become very popular, because they do not nee sufficiently long operation like filmmaking and platemaking. Image from computer directly printing on paper- it is very big advantage of digital printing. But there are some disadvantage of it. First of all, that it has low speed of printing. Second, it is favourable to use only for medium and shot runs. And third, it is problematic to level the paper in process of printing.
FINISHING Finishing is a general term that includes a number of different opera-tions and specialties. Most of these operations are highly specialized. Some finishing operations are performed inline with printing on web-printing presses. Two finishing operations quite often used are embossing (stamping) and diecutting.
Embossing The image is molded in embossing so that it is raised in relief. Molding is achieved by pressing the material to be embossed between a brass female die and a male bed or counter mounted on a press.
Light embossing may be done without heat on a cylinder or platen press. For heavy embossing and where fine detail is required, the die is fastened to a heated plate on a four-post press. Diecutting There are two methods in use today: high or hollow diecutting and steel-rule diecutting.
Hollow diecutting is a process used almost exclusively for labels and envelopes. A steel die is positioned on jogged pile of printed sheets. Pressure forces the die through the pile. The labels remain in the die until stripped out by hand.
Steel-rule diecutting is used for larger size dies or where close register is required. The latest developments in diecutting are laser-cut dieboards and rotary diecutters. Shrink-packaging Bindery automation
Flexography Flexography is a form of rotary web relief printing like lettepress but using flexible rubber or resilient photopolymer relief plates, and fast-drying low viscosity solvent, water-based, or UV inks fed from anilox: inking system.
Flexographic presses are web-fed machines of three types: 1) Stack type in which two or three printing units are placed vertically in stacks. A press may consist of two or three stacks, with unwind, rewind, sheeter or cutter and creaser;
2) Central impression cylinder which is like the common impression rotary lettepress and is used extensively for printing flexible films; 3) And inline which is similar to a unit type rotary press. Almost anything that can through a web press can be printed by flexography.
Products printed by flexography range from decorated toilet tissue to bags, pressure sensitive labels, corrugated board and materials such foil, hard-calendered papers, cellophane, polyethylene and other plastic films.