By Peter Claußnitzer, Managing Director, Design and Development, Harro Höfliger Verpackungsmaschinen GmbH
SubscribeHarro Höfliger provides expert knowledge in the field of web-processing technologies.
The Harro Höfliger Verpackungsmaschinen GmbH company has specialized in this area for many years, and has a worldwide reputation in the pharmaceutical industry as a development partner and provider of system solutions. Höfliger is in particular demand for the technical implementation of production solutions for drugs with new delivery systems.
This technology company, based in Swabia, Germany, can draw upon decades of experience in the area of pulmonary, subcutaneous and transdermal delivery systems. For each system, Höfliger provides product-specific solutions.
The company has made a special name for itself in a particular segment of the industry: the design of production and packaging machines for patches. Höfliger has been collaborating closely with patch manufacturers for more than ten years.
Höfliger development engineers maintain a continuous constructive dialogue with the pharmaceutical industry in order to develop optimal solutions that are customized for individual products. This type of cooperation results in highly developed production and packaging lines. As a pioneer in this field, Höfliger has now developed a new type of technology for processing all standard roll materials.
Variable line platform – intermittent or continuous motion
Fundamentally, two different concepts are used, based on the mode of operation of the production lines: synchronized operation and continuous-motion technology. It might be assumed that it is impossible to combine the two types of indexing; however this is not the case. The modular machine concept permits even the indexing of foil webs to be station-dependent, so that the type of indexing is determined by function.
Even with purely synchronized production lines, outputs are achievable today that could scarcely be imagined a few years ago. Patch products with several web layers and a width range of 100 to 350 mm have now become standard. Depending on the patch size, up to 1,000 patches per minute can be manufactured on Höfliger machines. The machine functions are controlled by high-performance PLCs, making it possible to handle unusual variants and sizes, as well as any conceivable shape, e.g. as round, polygonal, oval, sickle-shaped or sinuous. Programmable control permits different shapes and sizes to be implemented precisely, with optimal quality.
On such installations the retooling and adaptation to new production conditions is elegantly solved. After all, retooling without a considerable time loss is a decisive competitive advantage. For example, function stations on synchronized patch installations can be converted without difficulty. If further patch variants have to be manufactured, these installations provide another advantage: The production installations can be supplemented and expanded by complete frame segments. This shows the competence of the company in the product-specific design of manufacturing processes.
Continuously operating installations now predominate, particularly for high outputs and multiple sizes. Depending on the type of web material, the indexing units used permit web speeds of over 60 meters/minute (equivalent to an output of up to 2,000 patches). Just as the indexing units are driven by servomotors to achieve optimum operating characteristics suited to the web materials, servomotors also control the individual workstations. This guarantees maximum size range flexibility.
Due to both the modular structure of such installations and the decentralized supply, it is possible to adapt the line’s configuration at any time. As control is performed by servo-drives connected via a bus, either whole machine segments or just individual workstations can be retro-converted without a great expanse of work (see drawings).
While the purely mechanical conversion is performed by changing over individual stations, the electronic adaptation is based on an expansion of the structured software program. The program change for this can be performed either locally or by remote data programming performed by the specialist at the manufacturer's plant. The product-related settings are filed in a central product management system. In this way new products can be run in and optimized without the program having to be adapted and in production new parameters can be called off reproducibly in the event of a size changeover.
Another advantage of this modular installation platform is the balcony-type design throughout. With this type of machine design some of the workstations are arranged vertically on several levels. Optimized accessibility is achieved by this, which is to the benefit of the operator and considerably facilitates cleaning.
Product diversity and maximum output of the entire line
On an installation for the patch manufacturing market Höfliger has shown what is feasible in this field: Four different product groups each with up to six different sizes can be run on this installation. The control unit operates fully electronically, likewise product-related management of the setting parameters. This ensures the highest degree of quality in the production process.
Any sizes with infinite variation between the relevant minimum and maximum values can be produced on such a plant. This opens up undreamt-of possibilities, there being almost no limits to your creativity in production. The design potential provided in the web widths between 150 and 400 millimetres can be fully exploited. Through the use of this one machine it has been possible to close down several existing installations, which, despite the investment costs, at the end of the day has led to a reduction in unit costs.
Such installations are also frequently used for the manufacture of transdermal therapy systems (TTS). Fundamentally, it can be differentiated between two systems, depending on the product.
In the case of patches with a matrix layer the active substance is contained in the adhesive layer that comes into skin contact. Pads are punched out of these webs, then applied to a carrier layer and covered with a protective film. In a final process the TTS patches are packaged in-line in sachets.
The manufacture of reservoir patches is more elaborate since the active substance is applied on an upline dosing station. With this technology Höfliger's many years of experience in the realization of specialized pharmaceutical machinery pays off. The company has already developed a multitude of special dosing systems modified and adapted specifically to the product, no matter whether the medium to be dosed is liquid, pasty or pulverous. Optical control units ensure correct application to guarantee exact dosing.
In the further processing a lidding foil is applied gently and vacuum-sealed with a high degree of precision. In general reservoir patches are used for very high quality or high-dosage active substances. The process described involves precise dosing of the quantity of active substance required for a particular application. In contrast, in the manufacture of patches with matrix construction, some wastage of the active substance inevitably results from the die cutting of patch formats.
In contrast to pure wound dressings, with TTS patches an active substance is applied. If this active substance is a pharmaceutical preparation, another very different aspect suddenly comes into play in the selection of the machine technology: the validation capability in conformity with the guidelines of the American Food and Drug Administration (FDA). Höfliger engineers are familiar with this regulation system, which affects the mechanical construction, but mainly the software programming and documentation. After all, Höfliger has its origins in the design of specialized pharmaceutical machinery.
