Meet the modern tablet coater designed to tackle your coating challenges

It is essential to understand the evolution of tablet coaters and how modern advancements are tailored to meet a wide range of applications. This article explores how the design of tablet coaters has evolved to meet the challenges posed by modern tablet-coating needs, highlighting key advancements and future possibilities.

The origins of tablet-coating technology can be traced back to the introduction of pan coating, primarily used for sugar coating. While this method masked the bitter taste of tablets and improved their appearance, it was plagued with inefficiencies such as inconsistent coating, prolonged drying times, and extended processing durations—sometimes exceeding 48 hours.

To address these challenges, innovations such as the Pellegrini pan reduced processing times, though they were still limited in their functionality. The real breakthrough came with the development of the perforated coating pan. Unlike solid pans, perforated systems allowed for better air circulation and drying efficiency, making them a game-changer for the pharmaceutical industry. Perforated technology remains the backbone of modern tablet coaters, offering enhanced control over every step of the coating process.

Diverse tablet coating needs

Modern pharmaceutical products require a broad range of tablet-coating applications, from improving swallowability and aesthetic appeal to protecting tablets from environmental degradation or modifying drug release. Today’s tablet coaters must ensure not just high-quality coatings but also the flexibility to handle diverse production demands.

This has led to the design of equipment capable of producing batches of varying sizes, accommodating coating materials with different properties, and meeting economic and ergonomic requirements. Whether for small-scale R&D or large-scale production, manufacturers now need machines that provide consistent performance, comply with stringent cGMP requirements, and streamline processes such as cleaning and maintenance.

A holistic approach to equipment design is essential for addressing evolving needs. By incorporating advanced technologies, modern equipment not only meets current standards but also remains future-ready while boosting efficiency in pharmaceutical production.

Unique airflow pattern

In traditional coating systems, airflow turbulence often disrupts the coating process, leading to uneven application and wasted coating solution. To address this challenge, modern coaters such as ACG's SMARTCOATER X•ONE has a clear separation between the spraying and drying zones. By keeping these zones separate, as the tablets move into the drying zone, ample time is provided for the film-coating formation to dry before they cycle back into the spraying zone again. This unique arrangement enhances coating efficiency, minimising over spraying or deposition of spray-dried material throughout the process.

Reimagined coating drum geometry

One of the most critical determinants of uniform coating is the consistent motion of tablets within the drum. For every tablet to receive an even layer of coating, it must pass through the spray zone at the same speed and repeatedly present its surface to the spray nozzles.

Modern baffle designs provide significant improvements in this area, enabling optimised mixing in both radial and axial directions. Importantly, these designs allow for gentle handling, ensuring the integrity of friable tablets while maximising coating uniformity.

The geometry of the drum also plays a key role. Steep side walls and carefully positioned baffles allow tablets to mix efficiently, even with minimal loading, maintaining uniformity and avoiding inconsistencies in coating thickness. These advancements highlight the importance of process design in achieving reproducible results.

Sophisticated spray nozzle technology

Another major leap in tablet-coater design lies in the development of advanced spraying systems. Modern spray nozzles, incorporating technologies such as anti-bearding mechanisms and precise atomization, ensure an even distribution of coating material across each batch. The SMARTCOATER X.ONE features a patented nozzle developed in collaboration with Düsen-Schlick GmbH, which is now lighter and far easier to handle on the spray arm, specifically designed for large coaters, while maintaining user-friendliness and operational efficiency.

Its split nozzle design allows tool-less disassembly, separating the dock and nozzle elements for easy cleaning. These innovations enhance ergonomics, reduce maintenance times, and improve operational efficiency. Reliability in the spray system is paramount, as even minor inconsistencies can compromise coating quality and therefore production timelines.

Batch size flexibility 

Flexibility in batch sizes has become increasingly important in the pharmaceutical industry in recent years. Traditionally, 48-inch pans with 200-litre capacities or 60-inch pans with 500-litre capacities were the most common. However, driven by the need to reduce costs and improve efficiency, pharmaceutical manufacturers have shifted towards much larger coaters, with capacities ranging from 700 to 2000 litres. While increasing the diameter of the drum works well up to a certain point, it becomes impractical beyond that, as deep tablet beds can lead to tablet attrition and reduced productivity.

To address this challenge and accommodate larger batch sizes without compromising efficiency, modern tablet coating machines now maintain a consistent ratio between the length and diameter of the drum. When the diameter of the drum is increased, its depth is scaled proportionally—but only up to a 70-inch diameter. This prevents the creation of overly deep tablet beds, which can pose challenges with friable products and reduce the surface area relative to the bed size. For instance, in tablet coaters exceeding 700 litres, the SMARTCOATER X•ONE increases capacity by extending the drum along its axial direction rather than simply enlarging its diameter. This approach not only boosts the batch size capability but also significantly increases the spray surface area and the number of nozzles that can be installed within the coater, thereby greatly enhancing productivity for large batch coaters.

The SMARTCOATER X•ONE offers flexibility to accommodate a wide range of batch sizes. Instead of relying on multiple drums, which can be cumbersome and impractical, ACG designs its coaters to operate efficiently across batch sizes ranging from 10% to 100% of the drum volume. This versatility is achieved through innovations such as advanced baffle designs and adjustable nozzle arms that allow precise positioning of spray nozzles for different tablet-loading levels. Additionally, the use of simple, user-friendly stainless-steel devices streamlines the tablet loading and discharge processes. Integrated discharge scoops built into the front wall of the coating drum ensure smooth and effective tablet discharge during reverse rotation, assisted by product guide blades that direct tablets toward the scoops.

By combining adaptability with thoughtful design, the SMARTCOATER X•ONE delivers exceptional flexibility and productivity, meeting the evolving needs of pharmaceutical manufacturers while maintaining high efficiency and product integrity.

Superior cleaning system

Modern tablet coaters have been designed to accommodate sophisticated Wash-In-Place (WIP) systems that reduce manual cleaning efforts and minimise downtime between batches.

From integrated spray nozzles targeting critical areas to stainless steel construction with sloped surfaces that eliminate dead zones, modern coaters ensure thorough cleaning. A unique feature of the SMARTCOATER X•ONE is the integration of a lower section that allows for the accumulation of wash water up to a certain level, making cleaning with detergents far easier – particularly for coating solutions containing challenging polymers.

Effective cleaning, combined with ergonomic designs, makes modern coaters invaluable for minimising contamination risks and maintaining consistent product quality.

What lies ahead?

The evolution of tablet-coater design underlines the pharmaceutical industry’s commitment to innovation and excellence. From enhanced automation systems to even more sustainable designs using energy-efficient components, the future is poised for further leaps in technology.

Ultimately, meeting pharmaceutical demands requires not just robust technology but also intelligent design, tailored to the unique challenges of the industry. Modern coaters are achieving a perfect harmony of flexibility, performance, and compliance while supporting safer and higher-quality drug manufacturing.

The right tablet coater—backed by expertise and forward-thinking design—has the power to transform how you achieve manufacturing excellence.