Cold Set & Heat Set Web Offset Machines
Web offset printing machine is a form of offset printing in which a continuous roll of paper is fed through the printing press. Pages are separated and cut to size after they have been printed on web offset machine. Web offset printing is used for high-volume publications such as mass-market production of books, magazines, Supplements & newspapers. There are two methods of web offset printing, known as heat set and coldset (or non-heatset).
Cold set Web offset printing (also known as non-heatset) is a web offset printing process in which ink is allowed to dry naturally through evaporation and absorption. In the alternative method, heatset Web offset printing, ink is dried rapidly by forced-air heating. Web offset printing is a printing process in which a continuous roll of paper is fed through a offset printing press.
Cold-set Web offset printing presses are available from 20 inch to 22.75 inch wide range cut off sizes. This of course varies as large newspaper presses today are also mostly "cold-set." These web offset printing machines have been used mainly by the Newspaper printer to print newspapers & supplements, Book Publishers to print magazines, School Books etc.
Web offset press today is now printing higher volume production such as multicolour newspapers, Supplements, Books, etc. The market of newspaper printing machines are on an increase. The coldset web offset press manufactures today are even gearing their webs to compete against heatset web offset and sheet fed offset printing machines. Their motto; "Why print 5,000 impressions per hour when you can print upto 30,000?" It is because of this shift that the smaller press is being equipped with press consoles, IR or UV driers, better registration systems, etc.
Infeed :Paper is delivered to the web offset printing press by the infeed section. The infeed section typically contains a roll stand to hold the paper rolls; a splicer which automatically splices the end of one web to the beginning of another, a web-steering device which controls the side register (side-to-side position) of the infeeding web; and a tension controller that maintains the proper tension on the web as it enters the web offset printing press.
Printing Units : Web offset printing machines are made up of several printing units usually numbering from 3 up to or more than 6. Like sheet fed offset machine, each printing unit contains an inking system, a dampening system, a plate cylinder, a blanket cylinder, and an impression cylinder.
Delivery : The delivery section of web offset printing machine can consist of a variety of devices, from a simple sheeter, which cuts the moving web into sheets of the required size, to a combination sheeter and folder, which can both fold the web into final signatures (group of pages). These folders are available in half page folder, 1/4 page folder, 1/8 page folder & double parallel folder.