Empty capsules (two-piece hard gel or HPMC shells) are foundational in drug manufacturing. They hold powdered or liquid formulations once filled, so ensuring only perfect empty shells enter the filling line is critical. An Empty Capsule Sorter (ECS) is a compact machine that sits on the capsule-filling line to remove defective or unfilled shells before they reach the filler. Using compressed air and the Bernoulli principle, the sorter rapidly distinguishes empty or light capsules from properly filled, heavier ones. In this way it prevents under-dosed or hollow capsules from continuing downstream, boosting overall quality. Halo’s ECS, for example, creates a steady suction so that lighter (empty) shells are pulled off into a separate channel while heavier, filled capsules pass straight through. Connected directly to the capsule filler, an ECS can process up to thousands of capsules per minute – Halo reports a rate of about 7,000 caps/min for their model. By “catching” empty or half-filled shells on the spot, the sorter helps ensure only correctly filled doses advance to sealing and packaging.
An empty capsule sorter (such as the Halo ECS-600 shown above) sits between the capsule polisher/feeder and the filling machine. A stream of compressed air creates suction (Bernoulli effect) so that lighter empty shells are carried away into one outlet, while heavier filled capsules fall through the conveyor to the filler. This separation by weight ensures only intact, fully formed capsules move on. In practice, the ECS quickly removes any “empty capsules and half-filled capsules” that result from issues like a stuck cap or insufficient powder fill. The result is a smoother filling operation and fewer rejects later in the process.
Capsule Production Workflow
Empty capsule sorting is just one step in a multi-stage process. In a typical pharmaceutical line, the sequence looks something like this:
Capsule Polishing and Feeding: Raw capsules first go through a polishing machine (to brush off dust and fines) and a feeder bowl/orientation system. This ensures that only clean, correctly oriented shells enter the line.
Empty Capsule Sorting: Before filling, the shells pass through an ECS. The sorter separates out cracked, deformed, or empty shells using airflow as described above. This step is essential; without it, misaligned or empty capsules could be filled and packaged by mistake.
Capsule Filling: The sorted shells enter a capsule filling machine, which deposits precise powder or pellet doses into each capsule body. Fully automatic machines (e.g. Halo’s NJP series) can fill tens of thousands of capsules per hour, quickly depositing the formulation into each shell.
Capsule Sealing (Banding): Immediately after filling, most lines apply a seal to each capsule. The common method is banding, where a narrow gelatin or polymer band is applied around the junction of the cap and body. This can be done using an ultrasonic banding machine or a solvent-based adhesive. Banding locks the two halves together, making it extremely difficult to separate them without damage.
Quality Monitoring: Throughout production, quality is constantly checked. For example, sampling checkweighers (like Halo’s desktop SMC unit) periodically weigh random capsules from the line. The SMC machine can be programmed to ring an alarm at set intervals, prompting operators to take samples from the filler. It records capsule weights and charts their distribution, alerting staff if any sample is out of spec. This real-time monitoring catches fill errors (too little or too much powder) before large batches are completed.
Final Packaging: Once capsules are filled and sealed, they are packaged in bottles or blister packs. For blistered products, specialized equipment like defoiling and deblistering machines may be used. These machines peel foil or plastic layers off blister cards to free the capsules for inspection or repackaging. For instance, Halo’s full-automatic defoiling machine can strip about 60 blister boards per minute, while their ETC-120S deblisterer handles roughly 120 boards per minute for double-aluminum blisters. Such packaging machines are critical for high-speed production and in-line quality checks, as they allow quick access to capsules sealed inside blister cards.
Empty Capsule Sorter Operation
The core of an ECS is a simple physical principle. Compressed air is blown through special vents or nozzles, creating high-speed airflow across a flat sorting tray or conveyor. According to Bernoulli’s principle, faster air flow generates a pressure drop (suction) along the tray. Capsules traveling across the tray experience an upward suction force proportional to their mass. Heavy (filled) capsules have enough inertia to overcome this force and stay on the track, moving forward. In contrast, light capsules or empty shells are lifted off the track by the suction and diverted into a reject chute. An operator can adjust the air pressure to tune the suction strength for different capsule weights and formulations, ensuring accurate sorting even as batch materials vary.
This method is highly efficient. Modern ECS units are compact and can handle thousands of capsules per minute with minimal adjustment. Halo notes that their ECS can be connected to “any kind of capsule filling machine” and will sort at line speed up to 7,000 capsules/min. Because no mechanical parts touch the capsules during sorting, the risk of jams or capsule damage is very low. Also, the ECS design usually requires no change parts when switching between capsule sizes – a simple height adjustment or feeder adapter is all that’s needed to handle different diameter shells. In short, the sorter quietly and continuously weeds out bad capsules without slowing down production.
Quality Assurance and Related Equipment
Empty capsule sorting is part of a suite of quality-control measures. As noted, weight checking is commonly used in tandem. A sampling checkweigher (like Halo’s Desktop SMC) can be integrated alongside the filler. At preset intervals, it automatically samples filled capsules, weighs them, and logs the data. Operators can generate control charts or histograms to visualize the batch’s weight distribution, immediately spotting any drift or outliers. If too many capsules fall outside the specification (due to a malfunctioning dosing cam or a change in powder flow, for example), production is halted to fix the issue. This complements the empty-sorter by catching subtler dose variations that sorting alone won’t detect.
After filling and sealing, capsules typically move into packaging. Many products go into blister packs of plastic and foil. To inspect or process these later, lines may use deblistering machines. These peel or puncture blister cards to release the capsules. For example, Halo’s ETC-120S is designed for “double soft aluminum” blisters and works at about 120 boards per minute. A defoiling machine (or blister line opener) can remove just the foil layers to expose the pills. Halo’s 120 pcs/min defoiler strips blister foil rapidly (about 60 boards/min of flat blister cards). These packaging machines are especially useful in quality labs or repacking lines, where capsules need to be extracted from packets efficiently for secondary processes like rework, inspection, or bulk filling.
In summary, the empty capsule sorter is an essential in-line check that cleans up the capsule stream before filling. It directly ties into the larger flow of making high-quality, compliant capsules. By combining sorting, sealing, weighing, and proper packaging equipment, manufacturers ensure that every capsule leaving the plant meets strict pharmaceutical standards. Each technology – from Bernoulli-sorters to ultrasonic banders – plays a role in delivering safe, tamper-evident medicines to consumers.
Key Takeaways: Empty capsule sorters use airflow (Bernoulli’s principle) to remove undersized or empty shells during production. They fit into a production sequence that includes filling, sealing (usually by banding) and weight-checking. Sealing methods like capsule banding are commonly used to prevent leaks and provide tamper-evidence. In essence, empty sorters and sealing stations work together in pharmaceutical manufacturing to uphold quality and safety from the first capsule to the final package.
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Post time: May-06-2025