The Gravure Coating Machine and Its Processes
One thing you’ll notice as you explore different coating types is the popularity of gravure coating, and with it the gravure coating machine. We work with many different types of gravure coatings. We may favor a single coating process over others due to its specific qualities and capabilities, as well as the comparative efficiency of different approaches.
With that in mind, we’re walking you through the gravure coating options available. Look out for which procedures may fit your needs correctly. Everyone’s needs differ; but in the end, gravure coating could be what you’re looking for.
What does a gravure coating machine do?
Don’t feel alone—the gravure coating process isn’t one that everyone is naturally aware of. It’s rather specific, and with that in mind we’ll first explore how it works. Key to the process, of course, is the gravure coater, which is a form of roll coater. In the grand scheme, a gravure coater involves applying resin to a pre-engraved roll. After we apply the resin, we must use a blade to scrape the resin from the roll. This leaves the proper amount of resin left in the engraved “cells”. We then transfer that resin to a substrate surface, which forms a film.
Technically speaking, you’ll find many different types of gravure coating. You might be familiar with some gravure coating, but not all of them. Typically, you’ll see variation between processes depending on factors like blade structure, roll configuration, and transfer method. The main reason why we use gravure coating in general is because of their suitability for thin coating. Additionally, these processes operate at a high speed—when necessary—with high capability for versatility. There are so many types of combinations we can work through to tailor-make products.
What are the different types of gravure coating?
We can work through multiple processes with a gravure coating machine. Among them are gravure direct and gravure reverse, as well as kiss reverse gravure and doctor chamber gravure.
These processes work for different purposes, with different specific systems.
Doctor chamber gravure coating incorporates the fluid supply into the doctor blade itself, which speeds up the coating process. The system is semi-closed, which ultimately produces high quality results when you require a low coating amount in a high speed environment. Kiss reverse gravure, on the other hand, uses a kiss touch style, which puts less stress on the substrate.
Then, of course, there is gravure direct versus gravure reverse.
What is the difference between gravure direct and gravure reverse?
While on the surface they may seem very similar, there are key differences between gravure direct and gravure reverse. These differences don’t necessarily make one process better than the other, they do suite separate products in specific ways.
We’ve already gone over gravure direct—with engraved rolls acting as the conduit for applying solutions to substrates. However, the gravure roll coating machine can act in reverse as well. Typically, a reverse gravure coater functions with multiple pre-metered rolls. Usually, you’ll see three rolls within a gravure coating machine, and they all rotate in the same direction.
If you’re working with a nip fed reverse roll coater, the coating solution pools in the gap between the metering and applicator roll. As the applicator roll swings away from this pool of coating solution, it rotates and coats itself in the solution. The gap between the applicator roll and the metering roll affects the thickness of the coating. Another influence? The speed of the rolls. The faster the applicator roll moves, the more coating it deposits onto the web. Ultimately, the process results in the coating being applied to the web, the rotating causing a wiping effect.
We utilize both gravure direct coating and gravure reverse coating for film coating projects—it’s important to keep an eye out for soggy webbing. Additionally, we can use both processes for oil coating. However, with gravure reverse in particular, you must make sure to avoid incoming oil on the utilized foil.
What is the process of web coating?
When researching coating processes, you’ll probably encounter web coating. The purpose of web coating, of course, is to apply a number of different materials to various substrates. Of course, one form of web coating we must remain especially aware of is roll to roll web coating. This process relies upon several different rollers which work with a web path. That web path works the substrate material through the rollers. The rollers progress through multiple operations throughout the process.
The great thing about the process is that it’s an efficient way to apply materials onto substrates. As the substrate works through these rollers, we’ll see the material applied. You don’t have to work through quite as many steps as you do with other processes, while still receiving consistent, uniform results.
Who Helps With Gravure Coating?
Clearly, the processes and options available when it comes to gravure coating are extensive. Keep in mind that when considering a gravure coating machine, investing in your own permanent model may not be the right path. Fortunately, it’s definitely not the only one available. You can also work with a third party manufacturer, where you can have your roll coating needs taken care of by the experts, with a consistent, tested product.
No matter what option you choose, consider calling CTI at 419-924-5566 or contacting us here for assistance!