Technologies for tabletting effervescent products

Romaco Kilian provides the perfect solution for compressing effervescent formulations with maximum efficiency. An insight by Peter Heyn, Technical Marketing, Romaco Kilian

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Peter Heyn

Tabletting effervescent products makes many complex demands. Yet with the right technology, these tablets, too, can be processed rapidly and safely as required for the respective product. Romaco Kilian has the perfect solution for compressing effervescent formulations with maximum efficiency.

…because it fizzes. Children are particularly fond of effervescent products for this reason. The beverage and confectionery industries accordingly offer an enormous variety. Yet the pharmaceutical industry also provides numerous products as effervescent tablets, for example pain relievers, cough syrups or medications for the gastrointestinal tract. A broad array of nutraceuticals are likewise available, often in several different flavours. The administration of water-soluble drugs is especially recommended for children, the elderly or patients with swallowing difficulties or a sensitive stomach. The range of pharma dosage forms which can be purchased today is very wide and effervescent tablets are fundamental.

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Hygienic design of the tablet presses in the Romaco Kilian KTP X series

Tablets with complex demands

Effervescent tablets may have many benefits for the consumers to whom they are administered, but manufacturing and processing these hygroscopic products inevitably imposes complex demands. Effervescent tablets react extremely sensitively with air, light and moisture by nature. Many of the active pharmaceutical ingredients (APIs) and vitamins processed in effervescent formulations are easily affected by heat. Effervescent tablets moreover tend to be friable and break. All these factors must be considered when tabletting effervescent powders. The Romaco Kilian KTP 590X tablet press is tailor made for this kind of specification.

Gentle compression

Effervescent tablets are naturally prone to unwanted air pockets and capping, which is why the tabletting process takes place in three steps. The Kilian KTP 590X single-sided rotary press is consequently equipped with three separate compression stations. The first compression roller simply tamps the powder. Next, the tablets are pre-compressed while in the third step they are converted into finished products in the main compression unit. The use of Kilian 28/41 tooling simultaneously extends the dwell time, meaning harder tablets can be made because there is more time overall for deaeration. This stops the tablets from bursting later.

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Brake magnets eliminate frictional heat

Smoother than ever

Effervescent powders are hygroscopic with very poor flow properties. The fill shoes and paddles of the tablet press must therefore be designed to enable them to be filled efficiently and distributed uniformly in the die. The powder can also be lubricated with magnesium stearate to prevent the product from sticking to the tooling. An external lubricant supply system sprays the punch tips and the die walls during the production process. This has the advantage that the lubricant no longer has to be mixed into the product beforehand. Much less material is required for external lubrication. Harder tablets can be achieved as a result and the overall quality of the product is improved. What’s more, external lubrication protects both the product and the machine by reducing the tablet ejection force. Consumers thank the manufacturer for this at the latest when they take the tablets. Effervescent tablets which are lubricated by an external system have a smoother surface, contain less magnesium stearate and are dissolved in water without leaving a grease film.

Cool machines

Extremely low temperatures are essential in order to process temperature sensitive medications. The process temperature of the tablet presses in Romaco Kilian’s KTP X series is therefore kept at a constant level below 30° celsius. To reduce heat input, the compression rollers were fitted with smooth-running bearings and the gear of the fill shoe mounted externally. A special cooling ring, situated underneath the die-table, acts as a thermal barrier. The temperature in the service area is additionally lowered by the efficient cooling of the torque drive. The brake magnets also play a crucial role here by eliminating frictional heat and protecting the material. There is hence no need to install an additional cooling unit when tabletting temperature sensitive products. Not surprisingly, ‘cool’ is one of the three hallmarks of the Kilian KTP series.

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Swing-out die-table

Fast off the mark

If effervescent tablets are to be manufactured efficiently, it is vital to optimise the retooling and cleaning times. The number of product-contacted format parts in the tablet presses has been systematically reduced by Kilian for this purpose. Furthermore, the die-table, tablet chute and fill shoe can be swung right out for easy access to all components. Format changes can be completed without any additional tools. At the same time, the start-up dosing control based on the filling shortens the run-in times and avoids material loss. The OEE (overall equipment effectiveness) of the tablet press can be significantly improved under these conditions. Depending on the formulation, the Kilian KTP 590X achieves an output of up to 290,000 effervescent tablets an hour while with mono or bi-layer formats, the single-sided rotary press manages a maximum hourly output of 511,200 tablets.

Clean performance

Manufacturing effervescent tablets is an extremely dusty affair. A hygienic design is all the more important in order to keep unwanted dust formation in check. The compaction, retooling and service areas of the KTP 590X are strictly separated for precisely this reason. This prevents tablet dust from entering the machine compartment or, in the opposite direction, machine oil from contaminating the product. The patented punch bellows surround the upper and lower punches and protect the tablets from impairments in the form of black spots. The closed system, made from elastic synthetic material, is ventilated by means of holes in the die-table; it is affordable to purchase and inexpensive to maintain. The press’ fill shoe and tablet chute are fully washable and thus easy to clean. The concentration of particles in the production environment is greatly reduced by the dust-tight tablet chute. In short, Kilian’s hygiene concept ensures reliable processes and reduces the risk of cross-contamination to a minimum.

Safe processing

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Romaco Kilian KTP 590X

Once the effervescent tablets have been compressed, they must be further processed in line with the product requirements. Owing to their chemical and physical properties, effervescents are not stored in a buffer container but transferred directly to the downstream packaging machines. A special transfer station developed by Romaco conveys the fragile tablets from the press to the primary packaging unit. The tablets are fed from the scraper of the press directly to a Kilian conveyor belt running at high speed. Tailbacks of tablets at the press discharge are prevented by the acceleration, so that the products are removed and separated gently. This enables selective sampling before the tablets are distributed by a rotary table to the conveyor belt of the primary packaging machine.

On their way to this machine they pass via two more stations for dust aspiration and breakage elimination. Effervescent tablets are normally packed either in strips or in tubes. The Romaco Siebler brand includes both heat-sealing machines and tube fillers. Together with the Kilian presses, these two product lines form a functional unit for manufacturing and packaging effervescent tablets. Romaco’s effervescents portfolio is optimally complemented by Promatic cartoners and case packers.