gwk waterless dynamic cavity temperature control vario gt

The „green“ temperature control with recycled CO2
gwk waterless dynamic cavity temperature control integrat vario gt in the “weld-line competence centre”


In the “weld-line competence centre” gwk presents by means of demonstrators, graphics and sample parts an overview of available processes to produce high-quality moulded parts without visible weld-lines, flow lines and sink marks. Furthermore, gwk provides an insight into the actual state of developments that are realized in cooperation with industrial partners.


This also includes an extremely innovative “green” waterless temperature control system. By means of a demonstrator the actual state of development of the waterless cyclic cavity temperature control is presented that uses recycled CO2 as temperature control medium. Combined with the mould inserts with close-to-cavity temperature control channels produced by means of the integrat 4D-process the integrat vario gt allows the precise and fast heat transfer inside the injection mould.


Brand-new perspectives and possibilities are offered by the unique dynamic temperature control with CO2. This new and environment-friendly procedure really provides a solution for heating and cooling of complex and thin-walled moulded parts. By using a gaseous medium for heating and cooling, soiled cooling channels are now a thing of the past. Basically it is true that gaseous media have the disadvantage to be bad heat carriers. This applies at least to air that is only used for cooling processes under special circumstances. But in contrast, if the opportunities of CO2 are exhausted properly, it offers an interesting alternative to conventional water temperature control.


Cooling with CO2 is sufficiently tested and well-known. The high enthalpy of evaporation of the injected fluid accompanied by a temperature of -76°C offers an extremely efficient heat transfer. As far as cooling of long and thin cores or of narrow bars is concerned, cooling with CO2 has already been applied with great success for many years. Nevertheless, the new feature is that heating is also possible with gaseous CO2.


In the integrat vario gt that was developed by gwk CO2 is compressed to a suitable pressure and heated close to the mould cavity. In contrary to water and hot steam the medium is uncritically even in case of higher temperatures. It has got excellent heat transfer characteristics and does not tend to deposits and corrosion. These facts make it ideal for dynamic temperature control processes. The high temperature gradient between hot and cold media is unrivalled and promises minimum cycle times.


The positive environmental effects are also an important benefit: The CO2 applied is an extract of by-products from chemical processes, which would normally be emitted directly into the environment. Thanks to a new technique developed by Linde, ISK and gwk, however, it is refined and thus becomes suitable for the dynamic temperature control of narrow and otherwise inaccessible mould sections and complex part geometries. In contrast to all other techniques, this temperature control method does not put any requirements on the cooling system, neither in terms of temperature, pressure, volumetric flow rates or water quality. Thanks to this new technology the operation of water-free injection moulds in clean-room production is now within reach.

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