The application of medical coatings is an essential process that enhances the performance of medical devices. Most manufacturers use either semi- or fully automated coating equipment to coat devices, such as those by Hydromer®, Inc.. These systems are equipped with advanced, mechanized, and often robotic setups to get the job done quickly and more efficiently. They are also equipped with coating modules, such as spray coating equipment.
Automated systems usually include modules for surface preparation, coating application, and curing. The coating application module is arguably the most important because it controls how liquid coatings are applied to the device. This module often has submodules like dip coating, spray coating, spin coating, and meniscus coating.
Each different coating application submodule has specific advantages and limitations. Selection depends on device type and the coating requirements. Spray coating equipment is particularly effective for high-volume production, complex geometries, and ultra-thin layers.
This article dives into spray coating machines that are used in automated medical coating systems. Using Hydromer’s 40+ years of industry experience, we cover the different types of spray coaters, critical parameters, and key components of the machines. This article is intended for professionals involved in medical device production, such as Operations Managers, Coating Engineers, and others.
Overview of Spray Coating Equipment in Automated Medical Device Coating Systems
Uneven coatings on devices can cause complications, and these can lead to financial losses and reputation issues. The application method used is a key factor affecting the coating uniformity and overall quality of the film on the device. That’s why the medical device industry uses several proven coating methods, including spray coating.
Spray coating can be performed manually or automatically. Manual methods often result in lower coating quality, reduced transfer efficiency, and decreased productivity. Therefore, manufacturers use automated spray coaters to apply liquid coatings to medical devices.
The spray coater turns liquid coatings into a mist and then sprays it onto the target using high-performance nozzles.
Types of Spray Coating Machines
There are different types of spray coaters available for use. These include the following:
- ultrasonic coater
- air spray coater
- electrostatic spray coater
However, the majority of medical device manufacturers choose ultrasonic spray coaters due to their reliability and efficiency. You can see a comparison of these three types of spray coaters in the table below.
| Type of Spray Coater | Atomization Method | Waste/Efficiency | Key Advantage | Medical Device Suitability |
| Ultrasonic Spray | High-frequency vibrations (nozzle chip) | Very High (Minimal material waste) | Produces ultra-thin, highly uniform, micron-sized droplets. | Excellent (The industry standard for reliability and precision). |
| Air Spray | High-pressure compressed air | Low to Medium (Prone to overspray) | Simple setup, good for broad, less precise applications. | Moderate (Higher risk of uneven coats and material waste). |
| Electrostatic Spray | Electric charge (attracts fluid to substrate) | High (Creates a “wrap-around” effect) | Excellent coverage for complex, 3D geometries. | Good (But often requires the device substrate to be conductive). |
Ultrasonic Spray Coating Machines for Medical Devices
An ultrasonic spray coating device uses a chip (atomization surface) at the end of the nozzle. The chip is responsible for generating the vibrations using ultrasonic waves. The vibrations then convert coating fluid drops into a fine mist.
Ultrasonic spray coaters produce fine, micron-sized droplets using high-frequency vibrations. This ensures a uniform coating layer on device surfaces. Compared to other types of coaters, they drastically minimize material waste.
Steps to the Ultrasonic Spray Coating Process
Any spray coating process includes the following three steps:
- Coating Delivery to Nozzle: Liquid coatings are stored in tanks or reservoirs and transferred to the nozzle using precision pumps. These pumps are designed to maintain a stable, controlled flow rate.
- Atomization of Liquid Coatings: This is the primary step in spray coating. The process of atomization varies by the type of coater. In the case of an ultrasonic coater, high-frequency vibrations are used to atomize the liquid coatings into fine droplets.
- Droplet Transportation to Substrate Surface: The droplets from the previous step are transported to the medical device surface using low-pressure gas. Upon contact, droplets coalesce to form a thin coating layer. It should be noted that the proper adjustment of nozzle angle and distance of the spray is essential throughout the process.
These steps apply to all three spray coater types. Careful handling at each stage is necessary to prevent material waste and ensure process efficiency.
Major Components of Automated Spray Coating Equipment
A spray coater includes various submodules for precise coating of medical devices. It integrates easily into semi- and fully-automated systems and is widely adopted for its ability to coat curved and irregular surfaces.
Below we discuss the key submodules of spray coating equipment in more detail.
1. Atomizer or Diffuser
The atomizer is the key component of any spray coating system. It uses a high-performance nozzle to atomize liquid coatings and spray them onto the device surface.
The atomizer or spray nozzle controls droplet size and spray pattern during application. Its design varies by spray coater type. For example, ultrasonic spray coaters use a chip at the nozzle tip to vibrate the coating solution at high frequencies, creating fine droplets.
2. Motion Control System
During spray coating, either the substrate or nozzle is continuously moved, managed by the coater’s motion control system.
Companies such as Hydromer® use high-quality servo and stepper motors, sensors, and linear actuators to control spray nozzle movement precisely. Our equipment ensures accurate, repeatable positioning, consistent coverage, and ultra-thin coatings.
Many modern automated coating systems use PLC controllers and touchscreen HMIs for complete control of part movement.
3. Air Supply System
An ultrasonic coater uses low-pressure carrier gas, typically air or nitrogen, to shape the spray plume and transport droplets from the nozzle to the substrate. This function is crucial to the spray coater’s performance.
Unlike air spray systems, which use compressed air for atomization, ultrasonic coaters use compressed air to control droplet velocity and direction toward the substrate.
4. Filtration System
Hydromer® spray coaters include HEPA and activated carbon filters to extract volatile solvent vapors generated during spraying safely. The filtration system maintains clean air in the coating area.
During spray coating, a significant portion of atomized droplets may not reach the substrate and are released into the spray chamber environment. The exhaust and filtration system manages this overspray.
5. Spray Coating Chamber
The spray coating process occurs within a controlled chamber that manages airflow, overspray particles, and solvent vapours. It has observation windows that allow operators to monitor progress.
The chamber features containment walls and advanced filtration to prevent environmental contamination.
6. Coating Reservoir and Delivery System
Spray coaters store coating solution in reservoirs or tanks made of stainless steel or chemically inert materials. They are configured to maintain viscosity and have sealed lids to prevent solvent evaporation.
The storage system connects to a liquid delivery system that transports coatings from the reservoir to the spray nozzle. It uses various pumps, such as syringe, peristaltic, and gear pumps.
Inline vs. Batch Spray Coating Equipment for Automated Medical Coating Systems
Automated coating systems use two main spray coater configurations.
- Batch Spray Coaters: The batch spray coaters can process a group of parts in each cycle, making them an ideal choice for small-scale production. All parts are mounted on a huge rack during spraying. These can be purchased as standalone units.
- Inline Spray Coaters: The inline spray coaters are used for high-volume production. They use conveyors and robotic transport systems to apply coatings continuously to hundreds and thousands of parts per hour.
Inline sprayers integrate well into automated coating systems. They offer higher throughput than batch coaters and making them ideal for scalable production.
Compatible Coating Chemistries For Automated Spray Coating Machines
Various medical-grade coatings exist. However, not all of them are compatible with spray coating systems. That’s why, while choosing the coating chemistry, consider viscosity, volatility, and wetting behavior for optimal results.
The following are the most popular coating formulations compatible with spray coaters.
- Medical Device Hydrophilic Coatings: These are lubricious medical coatings ensuring safe and smooth insertion and navigation of operational devices. Hydrophilic coatings have been gaining huge popularity due to their customisation ability. These coatings can be customised for drug-eluting, antimicrobial, and thromboresistant properties.
- PTFE Coatings: PTFE stands for polytetrafluoroethylene. This type of coating is applied to medical devices intended for in vivo applications. They create a non-stick coating on the medical device surfaces.
- Silicone Coatings: These coatings provide lubrication and smooth surface properties. Their main purpose is to improve the device’s manoeuvrability. They are fully compatible with the ultrasonic spray coaters.
Note that spray coating systems are compatible only with liquid coatings.
Hydromer®: Hydrophilic Medical Coating Manufacturer and Coating Equipment Supplier
Hydromer®, Inc. has over 40 years of experience manufacturing and supplying advanced hydrophilic coatings. We also offer a comprehensive portfolio of coating equipment, including high-performance semi- and fully-automated systems, friction testing machines, and custom-built equipment.
Our automated systems support multiple coating application methods and curing processes, including Hydromer®’s proprietary UV curing technology, HydrUV™.
Our goal is to help customers achieve efficient, high-volume device production. Hydromer® collaborates closely with clients, providing support throughout the product lifecycle. We also offer a full range of coating services, including contract R&D, formulation, analytical testing, and more.
Medical Coatings Equipment Available From Hydromer®, Inc
Our two most popular automated coating application machines include:
- Hydrophilic Coating System: This automated system features integrated UV curing and is designed for applying hydrophilic coatings to medical devices. It requires only one or two operators and supports an annual capacity of 200,000 to 300,000 units.
- Fully Automated Coating System: This end-to-end solution is suitable for industrial applications and compatible with various medical-grade coatings. It requires a single operator and is ideal for large-scale production of complex devices such as catheters and guidewires.
In addition, we also offer friction testing equipment. Through 40+ years of manufacturing experience, we have developed a high-performance vertical and desktop friction tester. It is compliant with the industry standard YY/T 1898-2024. The equipment has been proven to measure the lubricity and durability of hydrophilic coatings accurately.
Contact our team to learn more about Hydromer® automated coating systems or schedule a demonstration.
