Technical strength has its own characteristics
Sheet-fed and web offset presses were invented almost simultaneously and have a history of more than 100 years. During this period, sheet-fed and web offset presses formed their own unique technical features.
1. Printing efficiency
Web offset printing presses are 3 to 4 times faster than sheetfed offset presses and can be folded at the same time as printing. In recent years, sheet-fed offset presses have also introduced multi-color double-sided offset presses and large-format offset presses, which make up for the lack of efficiency to some extent.
2. Production flexibility
(1) Print format
Sheet-fed offset presses are more flexible than web offset presses. A sheet-fed offset press can be arbitrarily changed in both length and width in a certain range. Now most web offset presses have fixed cutting lengths and can only adjust the width dimension. Although web offset presses that can adjust the printing format have now appeared, their adjustment is inconvenient and the adjustment range is small.
(2) Online function configuration
Online function configuration was originally an advantage of web offset presses, and in recent years sheetfed offset presses have also developed some online multifunction devices. On the whole, online multi-functional configuration is still a great advantage for web offset presses.
(3) Printing quantity
5,000 to 10,000 sheets are the range of printing numbers interleaved by sheetfed and web offset presses, and are also the competitive “zones†for both. In recent years, web offset presses have made many technological changes in their folding mechanisms, enabling a machine to print several types of prints (such as several newspapers, books, or magazines) at the same time, maintaining both the web offset presses. The high-efficiency advantage design solves the problem of reduced print batch size and greatly improves the printing flexibility. This shows that web offset presses will continue to erode the market for sheetfed offset presses.
3. Adaptive publishing of paper
Web offset press has better adaptability to newsprint, offset paper, letterpress paper and dictionary paper, while sheetfed offset press is more suitable for printing offset and coated paper. For thin paper, such as paper with a basis weight of 40g/m2 or less, it is difficult to feed paper by a sheet-fed offset press, and a web offset press can easily cope with it. However, the web is limited by the folding machine, and the basis weight of the paper cannot exceed 130 g/m2 in general. If a folding machine is not used, thicker paper can be printed.
4. Economic benefits
Due to the high efficiency of the web offset press, its overall efficiency is also higher. There are no systematic statistical data in China. However, according to the statistical data of different printing methods in the United States from 2000 to 2004, although the data is relatively old, it can also be compared that the difference in the profitability of different printing methods is still very large. Whether it is a cold-set or thermoset web offset press, the print profitability is significantly higher than that of a sheet-fed offset press.
5. Total investment in equipment and workshops
In terms of equipment investment cost and floor space, the equipment for sheet-fed offset printing presses is much lower than that for web offset presses, and it occupies less space. This is one of the reasons that many companies are restricted from purchasing web offset presses.
However, due to the integration of web offset press printing and folding, there is no need to purchase a separate folding machine. When a printing plant reaches a certain scale, the total investment in equipment and workshops may be less than that of a sheet-fed offset printing press. Therefore, the overall investment depends on the size of the printing plant.
6. Printing costs
Web offset and sheetfed offset presses also have many interesting cost differences. For example, the cost of substrates and inks used for sheetfed offset printing is higher than that of web offset presses (relevant foreign statistical data shows that the general substrate costs are 20% to 25% higher, and ink costs are 50% higher). There are fewer operators for sheetfed offset presses and more operators for web offset presses.
Moreover, in addition to a sheet-fed double-sided offset printing machine, double-sided printed matter is printed on a sheet-fed offset printing machine. When one side is printed, the sheet needs to be reversed, and the drying time is long, resulting in a long printing cycle and increased paper loss. The web offset printing machine can print ink on both sides, and the thermosetting ink printing can be dried in the machine with high efficiency. In addition, sheet-fed offset presses generally require dusting, increase costs, and affect the environment.
Application areas are their main
China's offset presses, especially those of web offset presses, have developed relatively late compared with foreign countries. At the same time, due to the use of printing presses in China and the problems of paper and other materials, the use of offset presses is still based on sheetfed offset presses. Annual production and sales of imported offset presses and domestic offset presses can fully prove this point. According to reports, in the commercial and packaging printing, most of them still use sheet-fed offset printing, so there is still much room for market development for web offset presses in China.
However, at present, China's newspaper printing has basically achieved 100% web offset, and only a few newspapers or internal newspapers still use single-sheet offset printing. In the well-developed areas of book printing, web offset printing develops rapidly and has a high market share.
Combining national conditions and forecasting development
In many countries, especially developed countries, web offset presses are mainly used in the offset press, and sheetfed offset presses are used as the auxiliary. Such as the United States in the 1980s, web offset has always occupied the largest market share, dominate the entire printing industry. In Europe (including Eastern Europe), web offset printing machines are also used. According to statistics, the market share of various printing methods in 2004 was 21.2% for sheetfed offset presses, 38.9% for web offset presses (21.0% for thermosets and 17.9% for coldsets), and 11.9% for gravure printing. Flexo printing 12.7%, embossing 0.3%, digital printing 8.6% equipment, and other 6.4%. According to the 2008 report of the Printing Machinery Division of the Japan Printing Machinery Industry Association, the ratio of sheetfed offset and web offset printing to the market is 2:8. According to reports from Japan, in recent years, the installed capacity of sheetfed offset presses has been continuously declining, and the installed capacity of web offset presses has continued to increase, indicating that the share of sheetfed offset printing presses continues to decline.
Taking into account the current situation of the vast ocean of sheetfed offset presses in China, China can only gradually switch to web offset printing. This has both customary issues and technical problems, as well as investment and economic strength problems in conversion. Therefore, in the future, China may be a relatively rapid development of web offset presses and double-sided offset presses.