Sheetfed Printing - Introduction

 

Sheet fed presses are used in the printing industry to print jobs that require lower counts. For example, if a printer was printing a job that required 50,000 impressions they would use a sheetfed press. On the other hand, if they were printing a wide distribution magazine, a high speed web would be used.

It was said, years ago, that sheetfed printing was used for quality printing and web for volume. Today, that is no longer the case. Web and sheetfed can both give equal print performance. It is more now a matter of your customer base and the length of run.

Figure 1 shows a common six color sheetfed press with a coater and infrared dryers. Each unit prints a different color. The usual sequence for printing is to print black, cyan, magenta and then yellow. The extra two units on the press are used to print special colors. The coater is used to give gloss or protection to the printed sheet. Between each print unit is a transfer cylinder to transfer the printed sheet from one unit to the other. As indicated in the picture, the ink is still wet during this transfer process.

Many of today's sheetfed presses are configured so that the sheet can be turned and printed on the back side. In the above press, it would be common to have the "turn" cylinder between the 2nd and 3rd print units. This is called a "perfector cylinder." The cylinder can be configured by the pressmen so that he can print 2 colors on the top of the sheet and 2 colors on the bottom or not configure.