Energy consumption reduced by 15 percent

Baumüller supplied an energy-efficient direct drive for a newly developed tablet press from Fette Compacting

In order to register lower carbon emissions in the future, the pharmaceutical industry demands sustainable and energy-efficient concepts. Like all machines in the new i series, The F30i tablet press was equipped with an energy-efficient drive system to meet this demand. Pharmaceutical producers  value a highly flexible, high-performance machine with a containment package and high output.

Tablets are solid dosage forms that may contain one or more active medical ingredients. They come in numerous shapes: round, oblong, oval, heart-shaped, star-shaped, and many more. The surface is usually flat or convex and may have scores, embossing or the like. Pharmaceutical manufacturers use fluid bed dryers for powder production. The powder is compressed into a tablet under high pressure, dedusted or deburred by a vertical deduster, and then packaged. The drugs are sold in pharmacies or dispensed to patients in hospitals or other facilities.

The dies and punches on the die plate are responsible for the shape and size of the tablet and can be exchanged / Image: Fette Compacting

Small footprint - Big impact

Based in Schwarzenbek near Hamburg, Germany, Fette Compacting is the world market leader for tablet presses in the pharmaceutical industry, with over 5,000 systems installed. The first tablet press from Fette Compacting was put on the market in 1948. The big breakthrough came in 1991 with the PT3090, the world’s first tablet press with an exchangeable rotor. Since 2016, the company has also manufactured special capsule filling machines.

Climate change is also an important global issue for Fette Compacting. “The pharmaceutical industry consumes an extremely high amount of energy. And, as in other industries, steps need to be taken to improve its carbon footprint. For this reason, we had energy efficiency in mind when developing the new i Series, including the F30i, in order to support our customers in their sustainability initiatives,” explains Jörg Gierds, Senior Product Manager at Fette Compacting.

The company therefore relies on an efficient drive system from Baumüller to produce its tablet presses. The solution consists of a DST2-315 water-cooled high-torque motor, a b maXX 5534 air-cooled servo converter, and two three-phase synchronous motors with integrated electronics (DSDI-036) and worm gears.

How the tablet press works

The machine operates according to the following principle: The powder enters the filling cone via a funnel and is filled into the existing segment bores by the filling cone wheel. To ensure that sufficient material can flow in, the lower punches are guided downward in a filling cam. The material is then dosed out. In this process, the lower punches are guided upwards along a dosing cam and dosed to the amount of material actually required. The excess material remains in the filling unit for further use. Product residues on the segment surface are transported by a scraper into the return chute. The material collected in this way is returned to the filling unit for pre-filling. After filling the segment bores, the powder is pre-compressed. In the pre-compression station, upper and lower punches press the air out of the powder. During the subsequent main compression, the already pre-compressed material undergoes final compression. The tablet now receives its final shape and breaking strength.

The finished tablet is then lifted out of the segment via the ejector by means of the lower punch. Tablets that are outside the tolerance limits are automatically sorted out and fed into the reject channel of the tablet discharge. All tablets that lie within the tolerance limits are conveyed by the tablet scraper into the “good channel” of the tablet discharge and conducted out of the machine. The lower punch is retracted and the process starts from the beginning.

A sample can be drawn at any time to check the hardness, thickness, and weight of the tablet. The goal is to make each tablet exactly identical, so that each contains an identical amount of active ingredient.

The F30i double rotary tablet press has up to 110 punches that can press up to 800,000 tablets per hour per compression station. This means it can produce up to 1.6 million tablets per hour.

The surface-cooled DSDI-036 motors including converter and worm gear (bottom left) continuously feed powder to the compression chamber. The DST2-315 high-torque motor (right) drives the large double rotary press in interaction with the b maXX 5534 servo drive (top left).

Constant speeds for high productivity

Two surface-cooled DSDI-036 motors with converter and worm gear are used. The challenge here was to design the motor to be as compact as possible and to fit exactly into the intended dimensions. The two filling drives ensure that powder is continuously fed into the compression chamber, so constant speeds are crucial here.

A direct drive (high-torque motor) is used to drive the large double rotary press. A blind hollow shaft motor was used for the purpose. This allows the machine spindle to plunge directly into the motor. Moreover, coaxial encoder mounting is possible thanks to a pre-assembled encoder kit. The encoder kit is a mechanical unit that is installed in the machine and can be quickly replaced if necessary. Another advantage is that the engagement position, i.e. the position of the rotor in the stator, does not have to be set up again.

The b maXX 5534 servo converter controls the water-cooled DST2-315 high-torque motor. The combination was optimally tailored to the F30i tablet press. Baumüller also undertook the drive dimensioning and initial commissioning of the tablet press.

The b maXX 5534 servo converter controls the water-cooled DST2-315 high-torque motor and is installed as a space-saving solution in the control cabinet / Image: Fette Compacting

Different high compression forces are required depending on the product. An effervescent tablet, for example, requires a high compression force of 100 kN, whereas soft tablets can only be compressed with 3 to 4 kN, as they will otherwise break. The compression force is also an important indicator for sorting out tablets that do not meet the standard. The punch-saving function detects the slightest fluctuations in compression force and sends a signal to the air-sorting nozzle for it to divert the faulty tablet into the “bad channel”. The direct drive is ideally suited for such variable applications and is also low-maintenance, quiet, and robust.

This is what the finished tablets look like after the compression process / Image: Fette Compacting

Smart teamwork

During the development of the F30i tablet press, Fette Compacting worked together with Baumüller as a competent partner. The perfect interaction of controller and motor made it possible to realize a machine with an output of up to 1.6 million tablets per hour. Compared to other tablet presses of the previous series, this new machine generation conserves more than 15 percent energy. This has been confirmed by energy measurements carried out by Fette Compacting: “In our applications requiring high compression forces as well as high speeds, the high efficiency of the drive in combination with the frequency converter makes a positive impact,” explains Jörg Gierds, Senior Product Manager Fette Compacting GmbH. The reason for the high energy efficiency of the system is the direct drive. This boasts not only high efficiency, but also precise control. As a further advantage, its compact design allows perfect integration into the machine. The system therefore has a high output density and enables precision in the process. End users can view and optimize the energy consumption of the machine at any time on the dashboard of the touch panel.

The F30i tablet press is efficient, compact, fast, and extremely energy-saving. A sophisticated drive solution allowed a 15 percent increase of the system’s energy efficiency / Image: Fette Compacting

Our cooperation with Baumüller has been going on for more than 15 years and is based on trust and an open and honest relationship!

Jörg Gierds, Senior Product Manager Fette Compacting GmbH

The F30i features extremely fast sampling of the first layer, by means of which the tablet weight can be precisely monitored and controlled. The mechanism works with an electro-pneumatic pressure roller adjustment and ensures that sufficiently hard tablets are produced quickly during the sampling of the first layer. At the same time, it reduces product loss to a minimum. The F30i also places a high priority on operator protection and a high level of user-friendliness.

Conclusion

The F30i tablet press is efficient, compact, fast, and extremely energy-saving. The powerful double rotary press is optimized for two-layer tablets. It impresses with its dust resistance, containment capability, system compatibility, and connectivity to Pharma 4.0. The machine has a wide speed range and therefore enables the production of a wide variety of tablets with precise dosing. The solid, cooperative partnership between Fette Compacting and Baumüller has yielded a compact drive system that benefits from constant speeds and high concentricity, increases the system’s energy efficiency by 15 percent, and improves its ecological footprint.