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Capsule Filler with Interchangeable Powder Dosing Trolleys

Almost every capsule filling machine on the market is capable of dosing the full range of fill media including powders, pellets, tablets, mini-tabs, and liquids. But several recent trends in capsule filling offer pharmaceutical manufacturers the possibility of doing more than just filling capsules. New developments in capsule filling technology can improve efficiencies as well as yields. The latest machines have on-board diagnostics and the ability to perform corrective actions during processing that directly address QbD principles, while increasing production efficiency. Highly flexible systems also have the capability to offer more unique features such as multiple powder dosing technologies, micro-dosing, combination fills and various ways to deal with common problems during production.

Latest Models Offer Flexibility

The properties of a given powder and the target fill volume help determine which dosing technology will produce  optimum results. While there are a variety of different technologies for dosing powder into capsules, the vast majority of capsule filling machines offer one of two basic dosing systems — either tamping or dosator technology.

A few low-output machines offer vacuum drum or vibratory systems. However, the newest models offer the ability to choose from each of these different dosing technologies, enabling the user to select the most suitable dosing system to match the properties of each different powder. Harro Höfliger is the only capsule filling system manufacturer that offers all four types (tamping, dosator, vacuum drum and vibratory). In addition, models are built for a full range of output speeds, producing 25,000 capsules/hour, 100,000 capsules/hour, and 200,000 capsules/hour.

The interchangeable dosing systems offered by Harro Höfliger enable a user to run any powder with a single piece of equipment, eliminating the potential need to purchase another machine with a different dosing technology. Harro Höfliger’s interchangeable trolleys allow dosing systems to be exchanged quickly and easily. Trolleys containing different dosing systems can be prepared offline while the machine is running. When changing to a different product, the module with the most suitable filling technology is wheeled into place and plugged in. System software automatically recognizes the new trolley, making changeover time faster and improving machine utilization. Off-line preparation of the dosing trolley and quick change size parts allow a complete change over to a new capsule size and different dosing system within 30 minutes.

The time-saving feature of interchangeable trolleys is primarily of benefit to users of low-speed machines, typically used in labs or clinical settings, where capsule filling machines may be used for many purposes and changed over frequently. With higher speed machines that run a few products and aren’t changed over often, the main benefit of the interchangeable trolley is the ease of access during changeover.

Dosing systems can be heavy and cumbersome to disconnect and remove. A rolling cart is easy to walk up to and roll out, and it provides unobstructed access to the station for maintenance, cleaning, and change-over. When the work is completed, the trolley is ready to roll into position.

Flexible Programming with Servo Controls

Harro Höfliger machines utilize servo controls, allowing each dosing station to be independently switched on and off. Sensors at the capsule infeed area monitor if capsules are present, complete, and fault-free. In case of a fault or missing capsule, the dosing station is switched off as that carrying segment passes beneath it. Traditional filling systems with mechanical drives don’t offer this capability since the drive motor is mechanically coupled to each dosing system. That means when something is jammed or there is an empty position, product will pass through the bore or fall onto the table. Servo controls allow a way to uncouple these movements and avoid wasting expensive or potent product. It also contributes to increased up-time as the machine will run cleaner and require less intervention for cleaning.

Servos offer users additional capabilities for dealing with problems. On the mid- and high-speed models, there are two eject stations. The purpose of the first station is to reject individual faulty capsules, while the second station is for good capsules. If there is a faulty capsule, users have two options. (1) They can decide if they want the machine to switch off the dosing station. In that case, no capsules will be filled in that cycle, and the remaining empty capsules are rejected at discharge. Very often, this is preferable to wasting a single dose of an expensive or potent product. (2) The second option applies to more standard applications. Rather than switching off the dosing station, the machine can be set to fill, then reject individual faults at the reject station. The remaining good product is discharged at the following station. These options enable the machine to be set up for optimum results based on each individual product.

On-board Systems Help Achieve QbD

With a trending emphasis on QbD, modern machines offer many ways to improve yield and minimize waste. Onboard systems analyze the process as it takes place and address problems as they occur, not minutes or hours later. They take corrective action automatically before small problems become big ones. The first step is to verify complete filling of capsules into the carrier segments. Non-separated capsules are immediately rejected prior to the dosing stations.

Some vendors offer on-board diagnostic tools that verify the capsule weight in-line and others offer check weighing systems that weigh capsules after they are filled. Harro Höfliger’s capsule fillers offer a unique system that verifies the quantity of product prior to being filled into the capsule. This system checks the weight of the product itself by measuring the mass as it travels from the dosing station to the capsule. As it passes through the sensor, it verifies that the proper quantity of product is filled into the capsule. This unique system removes the capsule shell from the equation, avoiding the uncertainty of capsule weight tolerances, and moisture content. These influences can negatively affect the accuracy in other systems that weigh after filling. This system is particularly useful in micro-dosing applications, where the capsule shell weight tolerance may exceed the product fill weight. A further benefit of this system is that it operates at full production speeds. Performing in-line weight measurement with this system takes no additional floor space, has no effect on machine speed, gives accurate results, and further improves process efficiency and productivity.

Harro Hofliger Modu-C MS with Fill Verification System

Checking for faults during capsule closing is another area in which Harro Höfliger machines improve quality and save time. They use the same basic closing process as other capsule fillers, but as the capsule is being closed, it is checked with in-line sensors at the closing station to be sure it has been closed to the proper closing length. If the occasional fault happens during processing, if a cap was missing or pushed down too far onto the body and split during closing, the automatic measurement system rejects the fault during processing. Most other capsule filling machines don’t have this capability. This final quality check with selective reject of the faulty capsule is another feature to improve the quality of the finished product and enhance the overall operation.

Micro-Dosing Systems

Another industry trend in capsule filling is micro-dosing. As opposed to traditional applications that fill several hundred milligrams of powder into capsules, micro-dosing requires fill volumes in the range of 15 milligrams or less per capsule and requires specialty equipment to ensure accurate filling.

Testing has shown the best dosing technologies to fill in this lower range are vacuum drum or vibratory feeding systems. Most capsule filling systems don’t offer these options, but all models from Harro Höfliger include this capability. They also use the weight verification system described above for ultra-precise control of the smallest quantities of powder, in the range of 2% RSD. Verifying product weight prior to dosing into the capsule is particularly important in micro-dosing, where the capsule weight must be removed from the equation to verify the proper fill weight.

Important Factors When Selecting a System

Most users want to know the obvious factors when purchasing a capsule filling system: cost, efficiency, uptime, reliability, and whether the machine meets output requirements. They should also be thinking about how easy it is to clean and change over, how the system can prevent product faults, and how much residual powder is left in the hopper at the end of the run. Harro Höfliger offers solid solutions for each of these considerations.

But there are also less obvious factors to consider that are just as significant. The type of fill media and properties of the powder are important to determine what type of dosing technology will produce optimum results. It is important to know if the powder is granular, fluffy, adhesive, cohesive, flows well or clumps and sticks, compresses into a slug or not at all. The target fill weight or volume is also important, whether 1,000mg or 1mg. Tamping and dosator systems are rather limited in terms of their effectiveness when used with highly cohesive powders with poor flow characteristics. To obtain consistent filling with acceptable RSD’s with these powder characteristics, vacuum dosing is recommended and highly effective.

Features that can add value to a user’s operation are also important. Concepts such as in-line quality control systems and unique approaches to resolve issues that have long been accepted as part of the capsule filling operation help meet today’s requirements when pharmaceutical manufacturers continue tightening belts and are asked to produce more with less.

A machine that meets not only today’s needs but adapts to future requirements is extremely important. New powder formulations may come along that require different dosing technologies. A highly flexible system may prevent the need to buy additional capsule filling systems when that new formulation won’t run on the existing machine.

Industry Leader in Dosing Powders

When looking for a capsule filling machine, vendor support and expertise matter. Harro Höfliger is a world-leading supplier of dosing technologies. It has extensive history developing various solutions to fill powders for the inhalation market. Harro Höfliger’s experience as a supplier of industry-leading dosing technologies for powders with various characteristics and fill volumes clearly translates as a benefit for pharmaceutical capsule filling as well.

No single dosing technology will be able to handle all of the required characteristics effectively, regardless of the supplier, or the dosing system the machine provides. The optimum solution is a machine that can run your current products, but offers the flexibility and range of dosing technologies to meet any future requirements. This is what you can and should expect from an industry leading equipment supplier.

© Interactive Pharm 2022

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