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New BlueFlow® hot runner technology has been made possible through ten years of research and development that has included practical evaluation with pilot users. The “blue nozzle” has already become well known following its presentation at the recent K2010 plastics industry fair in Düsseldorf and Euromold 2010 in Frankfurt.
A particularly efficient and easily regulated heating technology allows slim high- performance nozzles.
Although only launched shortly before the “K”, information about availability of an entirely new hot runner technology has spread like wildfire and stirred up a surge of interested visitors to the GÜNTHER Heisskanaltechnik fair stand. The fair event was dominated by questions about the design of the thick film heater, experiences of pilot users, application and installation possibilities, as well as costs for this new technology. Despite further product innovations in different hot runner technology areas, the thick film heating technology and the new possibilities that it opens in mould design formed the focus of the interest. Solutions already realised with the new BlueFlow® nozzle technology and their results gave impetus to developers’ fantasies. A green light has therefore been given for the “blue technology” in all plastics processing sectors.
Aside from the pre-dominating BlueFlow® theme, emphasis was also placed on nozzles for complex applications for side-gate injection, such as the OktaFlow® and PektaFlow® product ranges, as well as various drive techniques for needle gating.
Nozzle Typ SHT Blue Flow® Nozzle
At Fakuma 2011 (18.-22.10.), one of the most important trade fair of the plastic industry, GÜNTHER Heisskanaltechnik expects similar reactions from the market as at the “K”: fair visitors seeking energy saving hot runner systems that guarantee greater economy and process security for high quality-demands of complex projects.
Precision and costs under control Weißer+Grießhaber relies on BlueFlow® Hot-Runner Engineering for Micro Parts
Extremely thin-walled products with ultra-fine structures are a speciality of Weißer + Grießhaber. In a pilot application of the new BlueFlow® hot- runner nozzles from Günther Heisskanaltechnik GmbH, the company has engineered a more cost-effective production of precision filters, a safety component for the automobile industry, with greater process stability.
A micro filter (outlet valve for an automotive application) made of non-reinforced PA66 from Bada, injected in one processing step; 0.1 grammes and 1,848 apertures measuring 0.07 x 0.07 mm. The maximum permissible burring is 4.5 µm.
Already in the year 2009 the plastics processor Weißer + Grießhaber (www.Weißer-Grießhaber.de) from Mönchweiler, a town in the Black Forest area, was awarded “the innovation award for the promotion of innovative achievements in mediumsized industrial and skilled trade enterprises” for its directly injected filter. For the first time, filter screen fabric and threading were produced in pure injection moulding in one shot for these precision components for the automobile industry. This replaced the previous procedure, in which an existing metal or plastic screen fabric was overmoulded to obtain a ready-toinstall component. The impact on costs was significant, which, depending on the product, sank by around 60 to 80 per cent. In the meantime, a large number of variants are produced, in quantities ranging from several tens of thousands to doubledigit millions, for other industries too.
Such polyamide filters with weights of about 0.1 grammes are used for example in ABS and ESP systems to filter out even the finest particles from the brake fluid and accordingly ensure reliable functioning. Thread thicknesses of 0.10 to 0.15 millimetres and mesh apertures as tiny as 0.07 millimetres are scarcely visible to the naked eye. Burring must also be reduced accordingly to under 5 micrometres.
Precision times eight – the newly-designed Günther hotrunner nozzles reduce process temperature and the required pressure, which is also gentle on the material.
Weißer+Grießhaber spent about five years developing the directly injected filters. This concerned mould making above all and the moulds are still being constantly improved. The hot runner and control engineering as well as the adaptation of the process parameters have had a decisive influence on the qualitty and process stability. One of the decisions taken by Weißer+Grießhaber as part of the conti- nuous further development was to use BlueFlow®, the new heating technology developed and produced by Günther Hot-Runner Engineering, in their own manufacturing before the launch on the market and to evaluate the experience with it. The first obvious result of using the new nozzles”, explained Siegfried Kaiser, Head of Sales and Project Management at Weißer+Grießhaber, was the much lower temperature and pressure levels compared to the systems used before – which had also ranked among the top technologies. The temperature window used during the process is much smaller; the average temperature sinks and becomes more stable.” That not only reduces the strain on the mould; it sustainably saves energy and substantially reduces downtime. Another aspect, which is at least just as important, is that the higher temperatures and pressure levels before used to cause unacceptable material damage and consequently rejects. Furthermore, not all cavities in the 8-cavity mould were filled and the reject rate reached double-digit percentage levels. These problems are now over: GÜNTHER’s hot runner fills all cavities and the reject rate is less than 1 per cent. There is also a great improve- ment in injection gate quality.
Another aspect has been observed in practice: thanks to the fast heating and stable temperatures in the nozzles - nozzle temperature and setpoints are now at the same level for all eight nozzles -, the mould can be started up without any problem. Restarting after a fault is also easy now too. This also contributes greatly to reducing costs during the process and it increases process reliability.
Siegfried Kaiser: „… pays off in less than half a year…“
Keyword: BlueFlow® nozzle technology
The core element in the new nozzles are the thick-film heating elements developed by Günther and a project partner. The dielectric layer and the heating conductor paths are applied to a stainless steel casing in screen printing under clean room conditions and burnt in afterwards. A covering layer insulates and protects the heating element from external influences. The most important advantage of the thick-film heater: the heating traces can be brought closer to the material, allowing a much more precise output distribution over the entire heating tube because the conductor paths can be varied in terms of width (and output) and positioning. This makes it easier than before to achieve a high concentration of power in the front nozzle area, for example.
The entire heating element, is only about 1.00 mm. Compared to conventional brass heating elements, the new thick- film heaters are therefore much finer and have a narrower diameter. Other outstanding features in the heating elements are the high dielectric strength and non-hygroscopy, which puts an end to the previously customary slow heating to 100 °C and subsequent interruption in heating to drive water vapour out of the hot-runner systems.
The bottom line
The BlueFlow® technology is fundamentally compatible with previous nozzle systems and retrofitting is possible. The slight increase in investment costs must be viewed against the direct savings and increased reliability in Weißer + Grießhaber applications:
- Less downtime due to the faster and problem-free start-up, even after faults.
- Energy consumption is reduced by about to 30 per cent because the temperature is lower.
- Significantly less rejects due to the improved temperature control in the nozzles, reduced process temperature and lower pressure levels. The lower pressure allows the use of a smaller injection moulding machine as an alternative, which further reduces costs.
- Stable process with lower downtimes and accordingly a higher output.
- Heat loss is reduced, not only by the smaller outer contours of the nozzles but also by the low heat conductivity of the two-part nozzle shaft (patent: DE 412 70 36 issued on 4 May 1995) with its combination of materials, steel in the back and a titanium alloy in the front.
In addition, the new heating technology benefits from other features in the redesigned mould, such as the narrower diameter compared to that of conventional systems. This allows smaller nest spacing and accordingly smaller moulds or a greater number of cavities with the corresponding improved efficiency and yield. “A precise calculation of the cost per piece is not available for this application yet. However, the pay-off became evident in less than half a year”, said Siegfried Kaiser.
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High-tech hot runners
Günther Heisskanaltechnik GmbH has been involved in the development and construction of innovative hot-runner nozzles, hot-runner systems and supple- mentary technology for demanding applications since 1983, the year the company was established. Today the range of precise, standardised systems extends to special customised solutions developed in close co-operation with the customers. The company which is managed by Herbert Günther, founder and owner, and Siegrid Sommer manufactures exclusively in the north Hessian town of Frankenberg. Most of the customers come from the areas of medical technology, automotive, electrical and electronic industries, packaging and consumers. Subsidiaries in Austria, China and the USA and agencies in another 24 countries assure that we are accessible and close to the customers in the relevant markets.
Visit us at the Fakuma. We would be pleased to meet you on our booth (hall A2, booth 2207).