If you’ve been in the industry for a while, you probably know a lot about anilox and gravure coating rollers. You’ve likely heard them called “the heart of the flexo and coating press.” But maybe they aren’t something that you work with every day and could use a refresher, or perhaps you’re new to the industry and don’t know the first thing about these rolls. Either way, if you want to learn more about anilox and gravure engravings, this post is for you! My goal is to provide you with a quick and painless guide to selecting the best engraving for your business. With that said, over the next few paragraphs, I’d like to give you a brief overview of the rollers and the general purposes they serve, and to shine a light on the major differences between laser and mechanically-engraved rolls.
Let’s start with the basics: what function do these rollers serve? In broad terms, they are intended for use within two different industries – the printing industry, and the coating and laminating industry. Although there are many differences, the bottom line distinction between the two is that one uses ink and the other does not. Printers typically use anilox rollers in conjunction with printing ink that comes in three different chemical types: UV-curable and water or solvent based. Coaters and laminators, on the other hand, utilize coatings and adhesives that are usually only water or solvent based.
The distinction between the two industries is one that the average person won’t really see: printers handle practically all of the graphics, while the other (coating and laminating) does things that aren’t quite so obvious, sometimes even completely hidden. Examples of coating and laminating applications include things like laying down the glossy coating on a vinyl floor or working as a glue to adhere two substrates together.
When it comes to roller engravings, you have two basic choices: laser or mechanically engraved. As you can probably guess by now, there is a stark contrast between the two types of engravings and the final products that they are capable of shaping. A quick summary of the two types of engravings will help us wrap our minds around the information found in the following paragraphs. In a nutshell: laser engraving uses a laser to engrave a pattern into a ceramic surface. With lasering, the ceramic layer is then polished to provide an even plane in order to mitigate doctor blade wear during end-user operations. Mechanical engraving, however, uses a mechanical knurled engraving tool to transfer the engraving pattern onto a copper layer. The copper surface is then plated with chrome and polished for a smooth finish. Now that we’ve covered the basic principles behind laser versus mechanical engravings, let’s get a little more technical and dive into the more detailed factors that distinguish them.
Laser engraving encompasses two types of rollers: one is a steel tube roller and the other is what we call a “sleeve.” A sleeve is hollow in the middle and slides onto a shaft of the print machine. Whether you choose to utilize a sleeve or roll depends on how the end user’s machine is constructed. Either way, the process begins with a ceramic layer that is spray coated and machine polished until it is smooth in preparation for the final step: laser engraving. A solid-state, 500-watt laser then actually forms a pattern into the ceramic layer before it heads off to another machine for a final polishing process and then on to the end user (aka: printer).
This is where printing inks come into play. The printer takes the laser-engraved roller and transfers ink onto a photopolymer printing plate which then transfers the image onto a substrate (anything from paper to plastic) and viola: graphics! If you’re walking down the aisle of your favorite grocery store, any graphic you see is likely a result of this process. Think: beer bottle labels, bread bags – basically anything packaged with wrapping was likely created with graphics resulting from printing inks laid down using the anilox roll. Lastly, in comparison to mechanically engraved rolls, rollers engraved by laser are far more consistent and precise, and more durable due to the stability of the ceramic surface.
Mechanically-engraved rollers are very different from laser-engraved rolls in that they do not utilize inks. These rolls are labeled as mechanical because they make contact with copper to form a knurling (the pattern shaped into the roll). Then, once the knurled roller creates a mechanical engraving into the copper layer, the roll is polished smooth with a machine and topped with a chrome plating. The finished look is a layer of chrome – a dull silver. The knurled tool allows for a much deeper engraving than laser, which, in turn, provides the ability for a greater amount of coating or adhesive to be laid down in the coating process. These types of rolls are found most often in direct and indirect gravure coating applications.
Now that you understand the general differences between laser and mechanically engraved rollers, it helps to know that within each category there are further distinctions that can narrow down even further which is best suited for your particular application. If this is where you find yourself, it’s time to talk to your friendly rep about the specific needs of your business so that they can guide you to the best choice. Whatever the case, Pamarco has the roller for you.
For questions regarding anilox and gravure coating roller engravings, please don’t hesitate to contact me at firstname.lastname@example.org.