Detection and prevention at the same time
Glass defects in ampoules and vials threaten the integrity and safety of pharmaceutical products. A linear quality inspection and a carefully regulated container transport provide effective protection. Dr Thomas Jahnen, Technical Sales Manager at HEUFT SYSTEMTECHNIK GMBH, recently explained the options and advantages at the 15th Pharma Congress Production & Technology in Duesseldorf / Neuss.
What are the causes of defects in glass containers for parenteral drugs? Where do they occur? How can they be detected? And how is it possible to specifically prevent the dangerous breakage of glass? The "Glass – Glass Breakage – Delamination" conference of the European Compliance Academy (ECA) answered questions such as these at the largest congress of the pharmaceutical industry in the whole of Europe at the end of March.
Whether already in the glassworks, on the journey to the pharmaceutical manufacturer or not until the filling and packaging line: "Glass defects can occur anywhere along the complete processing chain", explained Dr Jahnen during his presentation. The main causes: thermal and mechanical stress. Therefore the high temperatures of the washing machine or during the hot air sterilisation can lead to damage on the line. The same applies to friction, pressure and collisions when filling, sealing and inspecting the containers.
Gentle container handling
The process forces of conventional rotary machines threaten the integrity of the packaging in particular: it is subjected to pressure during the combining and transferring process - infeed worms, starwheels, holders and centring bells often handle it much too harshly. At the worst the inspectors cause the defects which they should actually detect. "Ampoules with deformed tips can break in rotary systems with centring bells", according to the Head of the Technical Sales Department at HEUFT. "In comparison a linear inspector does not come into contact with these tips in the first place!" Starwheels and fixing elements are nowhere to be found in the space-saving HEUFT systems either. The result: empty and full glass containers are handled especially gently. They are subjected to virtually no mechanical strain during the inspection. A servo-controlled belt drive takes over the clearly defined, brand-specific controlled rotation for an optimal alignment at the individual detection stations – according to Dr Jahnen this is the "mechanical heart" of the HEUFT linear machine. For this reason they manage completely without any change parts for different sizes of containers. This makes product changeovers without tools at the push of a button a reality and minimises storage, maintenance and spare parts costs.
Consequently the continuous inspection of each individual container before the filling process also pays off which was not usual in the industry up to now. "The inspection of empty glass containers in a linear machine stands out because the investment costs are considerably lower than those of a rotary machine", according to Dr Jahnen. "A hundred per cent inspection is therefore also sensible from a financial point of view." Furthermore is it much more reliable than the conventional random checking of some packaging. The HEUFT InLine even detects critical finish defects which cannot be identified in already sealed vials using clever illumination and camera technology. In addition the inspection covers the base and sidewall completely. This also applies to areas with knurling marks or imprinted mould numbers. "They are often faded out because the influence of such glass structures on the detection reliability is too serious." In comparison the HEUFT reflexx² image processing system filters such good objects out effectively. Therefore scratches, cracks, inclusions, spikes, bird swings, chips, chipping and contamination are also reliably detected in these areas. The dark field inspection even makes residual stress in the glass visible which is invisible to the naked eye and affects the breaking strength of the glass.
A continuous inspection and transport without pressure
The inspection of full containers is linear, continuous and careful with the HEUFT spotter PH. The system tracks down damaged, incorrectly filled or contaminated pharmaceutical containers in addition to black spots and defects to the ampoule tips as well as faulty vial closures. Each one of them is "looked at from eight different perspectives for this so that the complete circumference is inspected in each case", explained Dr Jahnen. The detection of foreign matter is even possible in dark, cloudy or coloured liquids due to a bright field and a dark field inspection.
Careful handling is also important here in order to prevent serious glass to glass contact in the infeed and inside the inspectors as well as on the conveyors between two machines. According to Dr Jahnen the HEUFT synchron conveyor control system achieves this: "it ensures a pressureless flow without the sensitive containers colliding by means of various sensors and checking algorithms for optimally regulating the conveyor speed."
Consequently critical glass defects in packaging for parenteral drugs can be reliably detected using HEUFT equipment. It also protects them from occurring during the filling process at the same time. This message went down well with the numerous participants of the Pharma Congress. Great interest was also shown in the module for detecting black spots on ampoule tips which could be seen in action at the parallel PharmaTechnica 2013 trade show.