What is an offset printer – know the basics?

Defintion of offset printing

What is offset printing ?

Offset printing is a commercial method of transferring an inked image from a metal plate onto a rubber blanket before its applied to the print medium. These presses use cylindrical drums or rollers arranged in a sequence to impart ink to the print medium running through. It can also handle a variety of paper sizes, quality and volume but is mostly used for larger orders.

The printing task is broken down into manageable operations through consecutive processing towers stacked with inks,  rollers, splicers and heating elements.

What are Digital Offset Printing Machines?

Digital offset presses are best suited for premium quality, multi-color print feeds. They adapt to both small and large quantities very well. The current generation is all about digital displays and marketing, hence this category is the current trend. They can print from offline digital files hence like any software-based program it’s easy to change and not mechanically constrained. These are new age machines so incorporate the best of technological improvements in productivity, efficiency and outputs.
There are many manufacturers available and generally they print in thousands per hour hence suitable for very large-scale production jobs. They are also sized smaller especially helpful where land is expensive helping maximize the factory floor space. They do not have any constraints in terms of either thickness of paper or detail in quality, its as good as offset printers.
Unfortunately, they can be expensive and sometimes out of reach for importers.

What are Sheetfed Offset Printing machines?

If the job requires singular feed of paper then Sheetfed printing offset machine is preferred. Whether it be designs or content being printed on individual paper, cardboard, or other mixed media, the key focus is on the need for the medium to be streamed in one after the other.
Sheetfed presses are usually preferred for less volume jobs such as pamphlets, printouts, marketing material, weekly magazines, regional publications and other non-voluminous printing.It does provide great versatility in terms of both printing mode variety of media and colors.

Given the offset is not digital, the plating is manually registered therefore it cannot be altered and will always print at the same position for each sheet that feeds through the offset.

These can also print up to 20,000 per hour with very large print sizes. The quality of print and color can range from low to top grades, essentially providing commercial printers the ability to manipulate pricing to suit contracts.

What are Web Offset Presses?

Imagine a sensational piece of news in a movie being printed in a newspaper factory with newspaper spinning at high speed. That right there is the work of a web offset printing machine. The press works by cutting paper first and loading into the feeder section. Cyan, Magenta, Yellow and Black are the first to go onto the paper. There could be a fifth tower that is used for some sheen, varnish or optional color if required.

Continuous production of long content with paper reams rolling at high speed is the unique element of printing press. It might also be the origin of the word “press” to describe news media may have arisen from the web offset press.

These machines are known for their temperature detail to the process, where there is a “Cold” and “Hot” sections. The wet ink from the color towers are cooled, dried in a hot oven for mass and rapid moving outputs. Heat set printers utilize high temperature lamps or elements to dry the inks; they are normally used on coated or glossy paper. The cold web offset process is where ink drying happens slower into the paper essentially lending to low quality and slower production runs.
Depending on the machine, it can run 3,000 feet per minute and upto 25K paper reams cut per hour. Unfortunately, this type of press is facing declining demand and brands are slowly shrinking.

Rahul Raikwar

Rahul is an expert at offset printers

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