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Openair® plant for 10 years failure-free in operation at BSH
Photograph: Samo Uranjek
This Openair® plasma plant has treated the PP surfaces of white BSH immersion mixers before printing for ten years now.
Photograph: Samo Uranjek
The plasma provides for high activation and microfine cleaning of the rounded off PP surface and ensures optimum adhesion of the printing ink.
The Bosch und Siemens Hausgeräte GmbH - competence center for small motor-driven appliances - is located in Nazarje, Slovenia. It is responsible within the BSH Group for the development and production, the quality and worldwide sales of these products. The production of immersion blenders makes up the largest portion of the production.
For this product BSH built a new production line in 1999 with the goal to increase the capacity while reducing costs at the same time. With these considerations in mind, the previously processed, expensive ABS plastics was to be replaced, among others, by equally high-quality but lower-priced PP (polypropylene). There was only one problem: the difficult printability of PP. To enable printing of the rounded off handles of the immersion blender in tampon print, a previous optimal pretreatment of the polypropylene is mandatory since without microfine cleaning and high activation of the plastic surface a strong, long-term stable adhesion of the printing ink cannot be achieved.
Photograph: Samo Uranjek
BoŠtjan Štiglic, BSH Head of Industrial Engineering at Nazarje Works, with Irena Uranjek (right),
CEO at Rogac Plus
.
Pretreatment with corona, flame or low pressure plasma would have been conceivable on principle but these methods were not suited for the product given the particularly sensitive high-gloss surfaces. A corona treatment would have left "crows feet", i.e. mat lines on the plastics which would have remained visible while printing. In the case of a flame method, the gas would form cloudy, mat surfaces with the same negative effect on the appearance. A plasma treatment under low pressure would have necessitated a laborious vacuum chamber system on the one hand and could have hardly been integrated into the line on the other.
Photograph: Samo Uranjek
BSH additionally purchased the Plasmatreat RD1004 rotation jet specifically for use on dark polypropylene.
Photograph: Samo Uranjek
Plasma treatment by means of the rotation jet also imparts a perfect appearance to dark, high-gloss polypropylene and ensures adhesion of the printing ink.
The manufacturer found the solution to the problem in the Openair® plasma technology. The then young, innovative method was presented to BSH by the female engineer, Irena Uranjek, with whose company, Rogac Plus, BSH had already cooperated at the time. The test series revealed that this plasma technique not only provided the best adhesion results but was also the only method to leave no visible traces on white and very bright polypropylene. Moreover, the system had been developed for automatic production and could be readily employed by the producer inline. When black PP was introduced for the product, BSH additionally purchased from Plasmatreat the RD1004 rotation system which now also imparted a perfect appearance to dark, high-gloss material.
In December 1999 the new production line with the Plasmatreat nozzle system was commissioned. Since that time the plant has been in continuous operation. It is working round the clock on a 3-shift cycle, failure-free, and still with the same process safety and efficiency as before. Up to now 10,500,000 immersion blenders have been pretreated with this plasma unit at BSH Nazarje.
