Gravure Roll Coating: What You Need to Know
Gravure roll coating—you’ve probably seen it recommended quite a bit. But how does it stack up against alternate types of roll coating processes? You have questions, and we have answers. Let’s dive in.
What is gravure roll coating?
Let’s explore how gravure roll coating works—before you can decide whether or not this is the process you need, you must first understand what it is, after all.
You may hear the term “direct gravure coating” thrown about from time to time. In this case, we use an engraved roll (as opposed to other roll coating processes, which may not). The engraved roll, otherwise known as the gravure, controls the amount of product applied to the surface or web. Usually, we use gravures made of ceramic or steel, and the engraving on them is a cell pattern.
We either roll the gravure through a pan filled with solution, or we submerge the gravure entirely. That’s how the initial product comes into contact with the roll—and from there, we use a blade (called a doctor blade to scrape off any excess product). The gravure continues to roll throughout this process, and we introduce it to the surface. That meeting point can be found at a nip point, created between the gravure and a backing roll covered by rubber. Both rolls rotate at the same time, in the same direction. They move at the same speed as the surface (or web).
In conclusion, what’s really creating that transfer is the “nip force” created between the two rolls. But what affects the amount of product transferred is the size and shape of the cells themselves. While this is the main factor, however, it’s not the only factor. Consider the blade construction, for example—some blades may remove more or less product than others. The angle and pressure also impact this issue, as does the coating viscosity, surface properties, rubber thickness and hardness, and overall operating speed. With all this in mind, we’re able to work with precision.
What are the roller coating methods in general?
So, you’ve learned a lot about gravure roll coating. However, that certainly isn’t the only type of roll coating method available. They include:
Roll to roll coating. This is a fairly popular process, and involves passing a flat surface (or substrate) between two or more separate rollers. One or more secondary rolls apply the solution itself onto an application roll (think of it as the primary roll). We approach this step of the process after we adjust the gap between an upper roller and a secondary roller. As the substrate passes around the roller at the bottom, we wipe the coating off of the primary application roller. We then cure the substrate, and we shape it into the final form.
Reverse roll coating. This process notably involves a trough, and we use it primarily for adhesive coatings. Specifically, we apply those adhesive coatings onto flat sheets and film. After submerging a roller in the required coating, we transfer it onto a roller sheet. We coat the surface material continuously with an adhesive, feeding it between a pressure roller and a transfer roll. Just as with gravure roll coating, we use a doctor blade to wipe or scrape away any excess solution.
While these processes may seem similar to gravure coating in some respects, you’ll notice key differences. What these differences impact, most often, is the product for which we use each process. As previously mentioned, we use reverse roll coating most often to apply adhesive coatings onto flat sheets and film. Gravure roll coating has its own unique advantages that enable it to serve other tasks more effectively.
What is the advantage of roll coating?
Consider the advantages of different roll coating processes—and consider the universal advantages of the process in general. There’s a reason why we in the manufacturing industry rely on these processes so heavily.
For one thing, it’s fast and efficient. In manufacturing, speed and efficiency is always key, because most business owners either desire or need to scale up production at one point or the other. It’s difficult to scale up production when a manufacturing process is slow or requires too much variation. While we can alter and customize coating processes depending on a client’s needs, we don’t need to change basic procedures too much.
Of course, with efficiency comes affordability. The more efficient a process, the less product you waste. The less product you waste, the easier it is for you to keep costs under control. Additionally, time is money in a very real way when it comes to manufacturing. Keeping this process as time efficient as possible ensures that you as the business owner save money in the long term.
Furthermore, with gravure roll coating, the final product is more consistent. Roller coating produces the same product over and over. You don’t have to worry as much about inconsistencies in the final results. Not only does this cut down on waste, as we mentioned before; it also simply ensures a much higher quality product. That matters, especially when you run a small business wherein your product will receive scrutiny over time.
While there are several different roll coating processes to consider, and this can be daunting at first—it’s a good thing. The variations in roll coating processes means that you can choose a process that’s tailor-made for your specific needs.
Have questions? CTI is here to help. Give us a call at 419-924-5566 or contact us now. We’ll help you learn more about gravure coating—among other processes—and determine if this is the option you need.