The Slot Die Coating Machine: What it Does and Why We Need It

What makes the slot die coating machine so important? Trust us, we’ve got the answer to that question—and a lot more. Check out what’s really behind this innovative process!

What’s the difference between slot die coating and blade coating?

A prominent point of slot die coating is its status as a metered coating process. At the beginning of the process, the slot die coating machine deposits solution directly onto the substrate involved. It does so through a piece called the machine’s “head”. We set a predetermined deposit rate, with the substrate moving underneath the head during the process.

Here’s why that deposit procedure is so important. The amount of solution deposited determines the ultimate thickness of the coating. Any other parameters set before coating affect the coating’s stability and overall uniformity. It’s easily scalable and adaptable. We apply it to flexible substrates without issue, and can achieve high coating speeds over time.

A blade coating process functions a bit differently. A blade moves on top of the substrate, or the substrate moves underneath the blade. A small gap exists between the substrate and the blade, ultimately determining how much of the solution applies to the substrate. Think of it as a manner through which you can spread the solution over substrate.

Similarly, blade coating is rather scalable. It’s especially effective when used on thin film products. Over time, we’ve also discovered much success with this process in terms of uniformity and consistency. It’s fast and efficient, and we deposit the solution from a reservoir—what this means is that we can control the amount of product deposited without error.

The process is simple and versatile, but cannot create films with less than 10s of microns. Additionally, there are more precise processes, and patterns are not easily reproduced. While we often use blade coating for large scale coating productions, slot die coating is preferable when you’re initially scaling up.

What is the difference between slot die coating and curtain coating?

We’ve already gone over what’s involved during slot die coating. When comparing a slot die coating machine and its process to curtain coating, it’s important to note the slot die, positioned away from the substrate, with that distance between the two being a part of what determines the thickness of the coating.

With curtain coating, you’ll notice a much larger gap between the depositing applicator and the substrate. Not only the wet coating thickness, but other factors affect the different outcomes of curtain coating. The impingement velocity, web speed, density, and viscosity of the solution also make big differences. Curtain coating also supports the substrate with a hard surface. That surface is a moving support bed, or a precision backing roll. One thing this ultimately results in is a higher coating speed. Not only does this ensure increased scalability; it also affects efficiency.

Why do we use a slot die coating machine?

So, why do we use this process in the first place? What kinds of applications does it have, on a purely basic level. Keep in mind, we can utilize a variety of different liquid chemistries in this process. What this means is that you can use slot die coating machines to apply a diverse amount of solutions.

Some of the main types of solutions to work with include metal, glass, and polymers. As you can see, there isn’t a single type of product of solution served best by slot die coating. It’s a flexible process, and we’ll only see it more in demand as time marches on. This is because even now, we in the manufacturing industry seek out new ways to use the slot die coating machine. Some of the most recent and exciting research surrounding this system surrounds flexible, printed, and organic electrons.

Of course, the medical and pharmaceutical industries famously rely upon slot die coating. Think about it: many products in these fields require flexibility, which causes industry leaders to favor slot die coating even more. Ultimately, slot die coating is a booming business, and the products this process creates will be in demand for a long time to come. What this means is that you need to consider: is it time for you to buy a slot die coating machine yourself?

Should I buy a slot die coating machine?

If you’re going to need a slot die coating machine often, you might consider buying a machine for your own facilities. There are pros and cons to this approach. You may want the apparent convenience of having a machine on hand, and in theory it might seem more affordable to invest in a permanent machine.

However, there’s a reason why many business owners choose against purchasing outright, instead working with a third party manufacturer. For one thing, buying a permanent machine implies you’ll always need a slot die coating machine. Technology changes, processes change—and your business may change, too. What if the machine becomes obsolete to your needs one day?

For another, investing in a machine means investing in employees that can operate the machine. Likewise, since operating machinery can be dangerous, you need to consider insurance needs as well. Similarly, machines take up space.

This is why we recommend exploring a third party. It’s often more cost efficient, more convenient, and provides a better product in the long term.

No matter what you decide, CTI can talk you through slot die coating machines. Call us at 419-924-5566 or go here for more info!