The tablet coating process is now an indispensable step in the production of many drugs and health supplements. For different tablet coating types and products, you should choose appropriate coating equipment to achieve better product quality. This article will introduce different types of coating machines and help you make the right choice.
3 Types of Tablet Coating Machines
Standard Coating Pan / Conventional Pan Coater
The standard coating pan is a traditional piece of equipment that many commercial medicine manufacturers no longer use today. It is primarily used for small-scale production and sugar coating currently.
Main Components
A standard coating pan primarily consists of a circular metal pan (usually made of stainless steel), a motor-driven system, a coating solution application system, a hot air supply system, an exhaust system, and a control system.
Work Process
The tablets are placed in the metal pan, which is rotated by a motor, causing the tablets to tumble inside. The coating solution is sprayed onto the surface of the tumbling tablets (or applied using a traditional pouring method) by the spray gun. At the same time, hot air enters from the front of the pan, promoting solvent evaporation and drying, finally forming a coating on the tablet’s surface.
Applicable Types of Tablet Coating
- Sugar Coating: A standard coating pan is the traditional equipment used in the sugar coating process. Sugar coating typically involves applying 20 to 50 layers of sugar coating, each layer requiring spraying and drying.
- Film Coating: It is suitable for basic film coating, but does not perform as well as high-efficiency equipment for precision film coating.
- Research and Development: The standard coating pan is also suitable for small medicine factories, research and development centers, and small batch order production. (comparable to how specialized small-scale production lines utilize high-temperature silver crucibles to manufacture controlled pore glass for the oligonucleotide industry.)
Energy Consumption
The motor power of standard coating pans typically ranges from 0.25 kW to 7.5 kW, and the heating system has a power rating of about 1.5–6 kW. But we should remind you that the specific values depend on the model. Moreover, the hot air system consumes more energy because its drying efficiency is lower, requiring longer working times.
Coating Time
- Sugar Coating: Traditional sugar coating usually takes 6–24 hours.
- Film Coating: This typically takes 1 to 4 hours, depending on the tablet strength and process conditions.
Overall, traditional coating pans take longer than perforated coating pans because of their lower drying efficiency.
Batch Size
Capacity depends on the diameter of the pan. A 6-inch pan can handle approximately 1–2 kg per batch, while an 80-inch pan can handle up to 200–300 kg per batch. Common equipment typically has batch sizes ranging from 8 kg to 275 kg. You can choose the suitable size according to your needs.
Advantages
Compared to fluid bed coaters, standard coating pans have a simple design, are easy to operate and maintain, and are more easily adaptable for explosion-proof modifications. They are suitable for several coating types, including sugar coating and basic film coating. It is also suitable for small-scale production and research and development. Additionally, they require a low initial investment.
Drawbacks
Standard coating pans have low drying efficiency and require a long coating time. Insufficiently uniform tablet mixing may lead to uneven coating and large batch-to-batch differences. If you want to achieve optimal results, skilled operators are required.
Perforated Coating Pan / Perforated Drum Coater
Main Components
The core component of a perforated coating pan is a fully perforated rotating drum installed inside an enclosed processing chamber. The system typically consists of a perforated drum, a spray system, an air handling unit (AHU), an exhaust system, a WIP (Wash-in-Place) cleaning system, and a fully automated HMI control system.
Work Process
The tablets are loaded into the perforated drum, and the drum rotates, causing the tablets to tumble continuously. The coating solution is sprayed onto the tablet through a spray gun. Unlike standard pans, the hot air does not merely contact the surface of the tablet bed. It passes through the perforations in the drum and flows through the interior of the tablet bed, exposing every surface of each tablet core to the drying airflow. So the drying efficiency is improved.
Applicable Types of Coating
- Film Coating: Perforated coating machines are the industry standard for film coating and are widely used in both water-based and solvent-based film coating applications.
- Enteric Coating: Because they allow for precise control of temperature and humidity and produce a uniform coating, perforated coaters are the preferred choice for enteric coating. You can also use it to produce controlled-release coatings.
- Sugar Coating: It can also be used for sugar coating, but this is not very common.
Energy Consumption
Compared with standard pans, perforated coating pans optimize airflow patterns and improve drying efficiency, thereby reducing energy consumption.
Perforated coating machines equipped with an Energy Recovery System (ERS) can reduce thermal energy consumption, which can further reduce the machine’s total energy consumption.
Coating Time
Film coating typically takes 1–2 hours, which is significantly faster than the coating time required in standard coating pans.
Batch Size
Perforated coating pans are available in a wide range of batch capacities, from 5 kg per batch for small-scale applications to 500–600 kg per batch for large-scale production lines.
Advantages
The perforated design helps ensure that the tablets receive a uniform coating and achieve high drying efficiency. It also helps reduce waste of coating solution and lower production costs. Equipment with fully automated control can reduce manual intervention and operational errors. Professional CNC machining services also help manufacture high-precision pharmaceutical equipment components.
Drawbacks
Perforated coating pans are more expensive than standard coating pans and incur higher costs. The equipment has a relatively complex design and requires calibration and maintenance by qualified personnel. Moreover, some models may be difficult to clean.
Fluidized Bed Coater / Fluid Bed Coater
Main Components
A fluid bed coater is primarily composed of a vertical cylindrical coating chamber, an air distribution plate, a coating solution spray system, an air handling unit (AHU), an exhaust air filtration system, and a PLC automatic control system.
Work Process
Hot air passes through an air distribution plate, suspending the granules in the airflow to create a fluidized state. The coating solution is sprayed onto the surface of the suspended particles through nozzles, and the hot air instantly evaporates the solvent to form a coating layer.
The particles are continuously lifted to the top by the airflow and then fall naturally, only to be lifted again by the airflow. This process is repeated to achieve a uniform, layer-by-layer coating.
Applicable Types of Coating
- Pellet Coating: Fluid bed coaters are particularly well-suited for coating micro-pellets with diameters of 0.1–1.5 mm. They can also be used for coating powders and granules。
- Controlled-Release Coating: Fluid bed coating machines are widely used for controlled-release coating because they can provide highly uniform coating layers.
- Enteric Coating: If you need enteric coating, fluid bed coaters are also a good choice.
Energy Consumption
Fluidized bed coaters have high hot-air utilization efficiency, which helps reduce energy consumption. Fan power typically ranges from 7.5 kW to more than 100 kW, depending on equipment size.
Coating Time
In a fluidized-bed coater, drying and coating occur at the same time, and the process is faster than traditional methods. For the same product coating, a fluidized-bed coater can significantly reduce processing time compared with traditional coating methods, although results may vary depending on the different conditions.
Batch Size
Fluidized-bed coaters are available in a wide range of capacities, from small-scale for approximately 0.5–2 kg per batch to production batches of approximately 50–1,000 kg per batch.
Advantages
The fluidized bed coater has excellent coating uniformity and high drying efficiency. It also offers high material utilization and can conduct multiple processes, including mixing, drying, granulation, and coating. So it has a high return on investment.
Drawbacks
Fluid bed coaters are complex pieces of equipment that require specialized training to operate. And it requires a large original investment and is more complex to scale up than perforated coating pans. Moreover, if your tablets are very brittle, vigorous suspension motion and collisions between particles can easily cause them to break apart.
2 Types of Coating Spray Technologies for Tablet Coating Machines
Continuous Tablet Coating System
Principles and Features
The continuous tablet coating system operates in a continuous mode. Tablets are fed into the system continuously, and after being coated and dried inside the equipment, they are discharged continuously. By maintaining a constant tablet load inside the system, consistent product quality is ensured.
Advantages
The continuous tablet coating system offers little batch difference, a high degree of automation, and high production capacity. In addition, the coating material utilization rate is high. And the equipment requires less floor space for the same output.
Drawbacks
The initial investment for a continuous tablet coating system is extremely high. It is difficult to switch between product types, making it unsuitable for small-batch or high-variety production. Furthermore, the technology is complex and places extremely high demands on operators.
High-Pressure Airless Coating System
Principles and Features
The high-pressure airless coating system does not use compressed air to atomize the coating solution. Instead, a high-pressure pump forces the coating solution through a specially designed nozzle, where the high-speed liquid flow breaks up on its own to form extremely fine droplets. It is particularly suitable for high-viscosity, high-solids coating solutions.
Advantages
The high-pressure airless coating system offers high spraying efficiency and can cover a large area. It can reduce air bubbles and make the coating denser and more uniform. If the viscosity of your coating solution is high, it will be a good choice.
Drawbacks
The nozzles in high-pressure airless coating systems have small orifices, making them prone to clogging and resulting in higher maintenance costs.
FAQ
How to Select Different Types of Tablet Coating Machines Based on Different Budgets?
If you have a limited budget, you can choose standard coating pans. For a moderate budget, consider small-to-medium-sized perforated coating pans. If you have a larger budget, you can choose large perforated coating pans or medium-sized fluid bed coating machines. For high-end investments, we recommend large fluid bed coating machines or continuous tablet coating systems.
What Safety Requirements Need to Be Met When Using Organic Solvents in Tablet Coating Machines?
If the coating solution contains organic solvents such as ethanol, tablet coating machines must feature explosion-proof designs and hold the appropriate safety certifications.
When flammable solvents are used, equipment intended for the European market may require compliance with applicable ATEX requirements. If the target market is the United States, compliance with the relevant explosion-proof standards of the NEC must also be considered.
How Do Different Types of Tablet Coating Machines Differ in Terms of Cleaning?
There are significant differences in the ease of cleaning among different types of tablet coating machines. Perforated coating machines typically have a wash-in-place system, which is more convenient. Standard coating pans usually require manual disassembly for cleaning, making it difficult to ensure consistent cleaning results. Fluid bed coaters are the most complex to clean. Because they have many hard-to-reach areas, such as the bottom nozzles and exhaust filter bags.
When Considering Long-Term Costs, are there Significant Differences between Different Types of Tablet Coating Machines?
Yes, and you should not focus only on the purchase price. Although perforated coating pans and fluid bed coaters require a higher initial investment, they offer better energy efficiency and material utilization. So their long-term costs are often lower than those of standard coating pans. Moreover, fluid bed coaters can significantly shorten production cycles and help reduce long-term costs.
What Are the Different Space Requirements for Tablet Coating Machines?
The installation requirements for different types of tablet coating machines are different. Standard coating pans usually do not require special ceiling heights or modifications to the piping system. Perforated coating pans have requirements regarding plant ventilation and electrical capacity. Fluidized-bed coaters are taller and usually require a higher floor. Continuous coating machines require sufficient space for their intake and exhaust ductwork systems.
Final Thoughts
If you are planning to purchase tablet coating machines, it is very important to choose the right manufacturer. Pilotech is a professional tablet coating machine factory in China. We have over twenty years of production experience. We can offer you excellent quality and personalized services. Welcome to contact us!