Home > Coatings > Blade Coating, How It Works, And What You Need To Know

Knife Blade CoatingThe blade coating process has a broad impact on the industrial manufacturing industry—and Conversion Technologies International knows a thing or two about that! Allow us to break it down below.

What is a coating blade?

Sometimes, we refer to a coating blade as a doctor blade. It’s a remarkably precise knife used in the blade coating process—which, similarly, we sometimes refer to as doctor blade coating. The blade can be rigid or flexible depending on the project, and we use it to spread coatings across surfaces. The benefit of using the blade is that, as it moves, it scrapes away excess coating. This creates a smoother, more uniform surface. It also allows us better control of the process, ensuring we get the exact results we need.

In terms of the type of blade used, you’ll typically expect either a beveled blade or a bent blade.

  • A beveled blade is probably the most commonly used blade in the manufacturing industry. It works with an angled edge. This allows you to control the coating through speed, pressure, and that specific angle. A beveled blade gives you a good deal of control over the results, without complicating the process.
  • A bent blade usually applies a thicker coating. This is less about the form of the blade and more about how we position it. While we often associate doctor blades with thinner coatings, the real point of the process is smoothness and uniformity. The blade coating process allows us to execute that regardless of the coating’s thickness.

We often use this process on everything from textiles to paper, as well as films. The blades function in tandem with a roller or fountain, depending on your goals. While you can potentially handle this process in-house, many business owners choose to work with third party manufacturers like CTI. This allows you even more uniformity and precision. We’re experienced and know exactly what we need to do, with little trial and error.

How thick is the doctor blade coating?

Blade coating allows us to work with a wide range of coating thickness levels. In fact, results can range from 20 to several hundred microns. It truly depends on what you need, and the coating type. Some coatings are better suited to thicker coatings than others, and vice versa. Technically speaking, some doctor blades can control a coating’s thickness from zero to 3,500 microns, but you’ll typically want to settle within a smaller range for the best degree of control—at least in a manufacturing setting.

The adjustability of the coating thickness is one of the reasons why we so frequently rely on the blade coating process. However, we also consider other factors when predicting the final results. Typically, the final dry coating thickness is less than what you’ll see in the side gap setting–it’s important to anticipate this. Consider the blade gap, viscosity, and coating speed. While we can adjust the settings as we work, we’ll ideally plan everything in advance. 

Different coatings, of course, suit different applications. Consider:

  • General industrial coatings. This is where you’ll usually find the range between 20 and several hundred microns.
  • Electronic coatings. These coatings remain on the thinner side, comparatively. Usually, they sit under 100 microns.
  • Lab-scale coatings. While we don’t work with these coatings as much in a manufacturing setting, we do know their standard capacities. They’ll usually range from five to 100 microns.

What components make up a blade coating machine?

A coating machine includes several different components, some of which are adjustable. You’ll usually find:

  • A doctor blade. We’ve covered the basic elements of a doctor blade, but keep in mind that’s it meant to be as precise as possible. To avoid wear patterns, we can mount it on an oscillating blade coater device.
  • A coating head. The total assembly of this component includes L-shaped brackets, precision adjustment screws, or micrometers. These allow us to adjust the blade’s height and angle.
  • A substrate transform system. This includes either a platform for sheet coating or rollers for industrial roll coating (sometimes referred to as knife over roll coating). These move the substrate under the blade at a constant speed, allowing the blade to coat it as needed.
  • A coating reservoir. This container holds the liquid solution (alternately, at times, in a slurry form). It may also feature a pump, which dispenses the solution onto the substrate.
  • A driving system and motor. These components allow us to control the substrate and, sometimes, the motion of the blade.
  • A curing system. We cure these coatings through air-drying, heating, or infrared light.
  • A control panel. Digital or manual controls allow us to control temperature, speed, and the blade gap.
  • A base or platform. This is typically flat, made up of stainless steel or glass. It ensures a rigid surface, making the coating process easier.

FAQ

Let’s explore a few more questions beyond the basics.

What are the benefits of working with a third party manufacturer?

As previously mentioned, a third party manufacturer allows you to get consistent results quickly and efficiently. By outsourcing, you’ll save money on labor, facilities, and materials. You should definitely consider it if you see scaling up in your business’s future.

Can you achieve customized results with a third party?

Absolutely! A third party like CTI can customize the process for your specific needs. In one client’s case, we had to create a specialized lightweight coating that worked for a fiberglass substrate serving the wind and energy industry. This is why it’s important for you to consult with us—and offer details—before making a final decision.

What should I do next?

We recommend exploring the process further, and there’s no time like the present! Call CTI at 419-924-5566 or contact us here to get more detailed answers.