All-in-one flexo printing

Inline flexo printing, high-quality equipment, cost reduction, and overcoming various challenges were the main reasons why Converting in Wisconsin was awarded the Flexo Award in 2001 by the American Flexographic Technology Association (FTA). Non-coated Floral Essence napkins produced on medium format presses.

Pete Gretzinger, the flexo manager of Converting, said: “The printing and packaging of finished products is the key to distinguishing this kind of flexo process from other processes. When the company’s employees put the product in the box, they see the product again. The person is the customer.” He explained: When the napkin is printed, it will slide down the machine and be folded into a quarter size, counted and sent to the baler. The baler covers the top of the product. Wrap paper and seal the box. A detailed description of the UPC code and product is then printed on the transparent packaging. Finally, the packaged product is placed in the designated position for shipment. Gretzinger goes on to say: "In other processes these steps are usually performed offline and on different devices. For us, on-line operation has saved us a lot of time."

The napkin product is printed on a six-color in-line layer flexo press. The flexo press is associated with a press-embossing device, a folding device, a cutting device, and an automatic transfer device. According to Gretzinger, the prepress cost in gravure printing is higher because of the need to sculpt the roller, and the embossing cannot complete the edge-to-edge printing, and the oil-based ink emits an odor that makes it less attractive. . The 26-inch-wide Serv-o-tec 806 press uses water-based ink and completes all steps from printing to packaging in one pass.

In addition, there are many economic factors that need to be considered in the production process. Gretzinger said that after printing on this two-layer napkin, it will have a three-layer appearance and bring them a certain cost advantage. They do not produce three-layer napkins but high-quality double-layer napkins. He suggested using Cellu tissue paper, which is a good material. Compared with other brands, this paper towel can absorb ink better. In addition, other brands of paper towels are also prone to curling or shrinking.

"Our next move is to replace a new squeegee system. Interflex's squeegee system is very good. The squeegee system allows us to print fine screen lines, cleaning and setting speeds are also improved. It saves us a lot of money spent on cleaning and setup. From a quality point of view, it helps us to reduce the dot gain in the printing process."

How to reduce plate breakage is another cost consideration. Gretzinger said: "Because we are using a continuous press, we have to use flat panels. Of course, you can also use bullets to avoid damage to the plates, but the cost is quite high." He added that people are increasingly thinking of maintaining The smallest plate breakage is more important than the purchase of a continuous sleeve.

Another requirement for Gretzinger customers is that the napkins can perfectly match the cardboard. Gretzinger said: “We use cardboard as a benchmark. First we print the cardboard and then we match the printed tissue with it. This is usually difficult because the cardboard is coated. The ink is easily absorbed on the napkin and the ink is It resides on the cardboard surface. Whenever you print on paper towels, the ink is always immersed, making the paper towels very dirty and dark."

He said that when applying a special color on a napkin to a cardboard or cup, the two colors would be very different. For example: The same red print on napkins and cardboard, the two colors are not the same. Because different substrates absorb inks differently. Therefore, the ink must be handled skillfully. Gretzinger said: "We re-adjusted the ink formulation so that it can match the cardboard material. In this process, we usually use a spectrophotometer and hand proofing."

Fine screening and stringent registration requirements increase the difficulty of work. Gretzinger said that there are no crosshairs to avoid misregistration; there are highlights and dark spots on the same plate; rough and dusty substrates. It is even more necessary to keep the screen clean. Every time you print, you must pay attention to the ink coverage. You can't just simply repeat a percentage of the ink coverage to avoid wrinkling. Gretzinger said that their workers use a roller cleaner to clean the dust that accumulates on the paper. This requires a shutdown.

Roller cleaning is a vacuum system that cleans excess dust before it enters the task scheduling system. It is actually two steel rollers that apply pressure on the paper, compress the fibers and make the paper stack neat and flat. You need to adjust the softness of the paper as much as possible, but the surface of the paper must be flat.

The problem of inability to dry on printing presses also requires careful attention. Gretzinger said: “We do not have the ability to dry the printed sheets between each unit, the only method that can be used is IR (infrared) drying. We use infrared drying after the printing unit, and also use a heating roller to dampen the moisture in the paper. When using metal inks for printing, it is more difficult, if only relying on the air is difficult to completely dry the printed sheets.To solve one of the problems, Gretzinger arranges the printing sequence of metal inks to the end.Gretzinger said that through this arrangement The metal ink can be completely dried and it will not be contaminated with other inks.

According to Gretzinger, customers are satisfied with the entire range of products, from napkins to paper cups to tablecloths. The customer was even thrilled that the product won the FTA Gold Award. Gretzinger said that the customer proudly mentioned the award in his product catalog.

Gretzinger trusts operators and retailers who serve their paper products. He said: "Our pre-press staff (Green Bay Engraving) is an important reason for our rapid success, because they can understand our craft well. In addition, in the development of a product for high-quality napkins, Premier Ink Systems has also invested a great deal of time and effort. You will be as successful as these companies that help you, because these companies play a very important role in achieving the goals.”

With regard to the flexographic process of silk fabrics, the problems of fabrics and napkins have been solved. Gretzinger said: “Things are steadily developing. Now we can achieve finer screens, and the number of screens in the past has been very low. The design we print now is the essence of the process change. A 1% outlet on the site is now 5% and 6%. We are now able to control a fine and strict dot size to print on napkin products. This is the biggest progress in the past 10 years."