Thursday | 11.05.17 | Specifications
One of the main label printing methods. FLexographic printing explained.
The biggest role in our production process takes the Flexo printing. There are a lot of details to be considered in this type of printing, which we will explain here in an easy way. Let’s see what flexographic printing can do and why it continues to be one of the best methods for producing custom labels.
The principle explained
With Flexographic printing the ink transfers onto the material using rubber printing plates mounted on fast-rotating cylinders. “The image areas are raised above the non image areas on the plate. The 3d plate takes the ink from the anilox roll and transfers it on the material. The texture of the roll holds a specific amount of ink since it is covered with thousands of small wells or cups that enable it to meter ink to the printing plate in a uniform thickness evenly and quickly. The substrate is finally sandwiched between the plate and the impression cylinder to transfer the image. The band is then fed through a dryer, which allows the inks to dry before the surface is touched again.”
The printing plates used on our machines are made on eco-friendly technology by our specialist. They are produced from photo polymer materials that is back exposed, laser engraved with the image in the desired resolution and then developped to the point of raised relief. The result is 3d rubber plate, which we cut to the size of the image and stick on the rotating cylinder on the flexo machine. The ready rubber plate can be used for at least an year and then has to be produced again.
About the inks
For the purpose of flexography are used Solvent, water-based and UV inks. In addition they consist of drying accelerators, additives and binders. The processing aids and additives make it possible to precisely tailor the properties of the ink, such as abrasion resistance, flexibility, glide performance, optical density and color strength. The machines that we use have 8 ink basins with possibility to print 6 colors on one side and 2 on the other. The get the desired color the inks are mixed according Pantone catalogue and then test printed on the material.
For getting the label to a certain shape, the printed band is pulled through another station on the machine where it is cut with a cylindrical engraved die. The die cut form is usually custom made( we order them from outsource company). The forms have the possibility to kiss cut and make a perforation. The waste, or matrix, is lifted and removed from the liner so it makes it easy to remove the label.
The materials we use for the flexo printing process for labels are mainly - satin, cotton, polyester, taffeta, tyvek, polypropylene, paper, non-woven material and self-adhesive materials. The fabric materials we use are mainly slitted to the correct width in house.
About the process
The operation of Flexo machine requires a professional touch. There are some specifics that are learnt with the practice. The main duties of the operator include sticking the printing plates, replenish the inks, testing and looking throughout the process for failure, matching the colors and cleaning the machine after each use.
The end products