Knife Blade Coating: How Does It Work?

Knife blade coating is a process that you might need to utilize as a business owner for many reasons. Typically speaking, we utilize knife blade coating for more wide scale coatings. Additionally, it’s used to create thinner coatings from high viscosity solutions. Due to the fact that it’s quite simple, it’s also perfect for more industrial coatings. And on a basic level, this process works for both paints and battery technologies, as well as ceramics and thin-film electronics. Due to its diverse applications, knife blade coating is quite appealing to many business owners. However, is it right for your purposes?

It’s incredibly important that you understand exactly how knife blade coating works before deciding on whether or not to utilize it. With that being said, let’s dive into this process and how it can benefit you.

What is Knife Blade Coating?

The question is, how does knife blade coating work? This process is important, and you can compare it to the doctor blading technique. With knife blade coating, you locate the meniscus between the web and the blade. We deposit a layer of product at the knife as it remains stationary, and an ink reservoir keeps supplying the meniscus over time. The place of the web and its movement ensures that we can deposit the layer properly. The gap size between the knife and the substrate affects the thickness of the layer—though the web speed can have an effect as well. Furthermore, the knife size can determine the consistency of the layers.

Essentially, we apply an excess amount of coating material to the substrate itself. The blade removes that excess through its repetitive motion, which ultimately thins the layer until it’s at the thickness level you require.

Why Do Business Owners Use This Method?

One of the most common (and visually distracting) issues you can encounter when applying coatings is consistency issues. Products can look vastly different from each other when we apply substrate incorrectly—perhaps the coating is too thick, or perhaps it’s not leveled the way it should be.

Knife blade coating makes this much less of an issue by allowing you more precision than alternative methods. A blade coater has an effect similar to scraping, and when using it you can be more certain about not only the quality of a single product, but all the others manufactured in the same facility.

While in theory knife blade coating may seem relatively simple, it’s more complex than it appears on the surface. Furthermore, it sets itself apart from processes that seem apparently simple—but perhaps a bit more deceptively than you realize.

What’s the Difference Between Knife Blade Coating and Slot Die Coating?

On the surface, knife blade coating and slot die coating may seem quite similar. In both processes, the product used (usually ink) is typically applied through a coating head or by pouring an excess amount onto the surface. With knife blade coating, however, the distance between the blade and the substrate is much more important, and has a greater impact on the thickness of the layer.

With slot die coating, on the other hand, we make the coated layer homogenous through ink being continuously spread over the substrate. This creates stripes. The web speed can affect the thickness of the product, as can the pumping rate and the width of the aforementioned stripes. At times, you may see slot die coating recommended for projects that are moving up from a small order to larger scale manufacturing. Slot die coating is also a great option for those that want to stretch thin layers over broad surfaces.

However, slot die coating cannot produce thickness layers below 10s of microns. It’s also not as precise as certain other techniques, and cannot provide patterning. If even minor amounts of contamination occur, the final product may have unsightly streaks. Additionally, the wet layer film thickness is difficult to reproduce.

What Are the Advantages of Knife Blade Coating?

When it comes to knife blade coating, the benefits are myriad. There’s a reason why we favor this process for certain projects over not only slot die coating but roll to roll coating. Some of the most common benefits include:

• The process is easily scalable, which means that you can produce many thin films over a relatively short period of time. As your business grows, scalability will become more and more important.
• You get a level of control over the solution deposited. What this means is that you waste less solution, and therefore lose less money and product. This type of precision is key.
• The process is simple, but it’s easily altered to ensure that it accommodates whatever customized elements necessary. You can change the thickness of an applied solution, or for that matter its viscosity, with relative ease.
• Generally speaking, this process is relatively inexpensive. It’s even less expensive, potentially, when you work through a third party manufacturer that has the connections and equipment you need!
• This process coats both rigid and flexible substrates, increasing its overall viability.

So, now that you know the basics of knife blade coating—what’s next? We recommend getting in touch with an experienced third party manufacturing company to see if they can offer some help on getting the ball rolling. There are many reasons why executing knife blade coating through a third party manufacturer is better. Let CTI walk you through how that would work. Call us at 419-924-5566 or contact us here to discuss more.