WAB: Water Assited Blowing

PME and Teklas Kaucuk have developed an innovative process for the production of the  drain channel which  combines the water injection technology (WIT) with the melt push back process and the blow molding technology with core puller technology [WAB = Water Assisted Blowing]. Dr.-Ing. Rudolf Fernegel expressed enthusiastically. "You simply have to look at this part to realize it". In that phase in which you think that the part should already be solid the blow molding technology steps into the process to elongate the material and to achieve a tolerance compensation.” 


The biggest innovation is, however, the implementation of this idea as a two cavity mould and the required development of a new machine equipment that enables this process combination.


The process works as follows:

The pipe injection mould offers variable cavity geometries in the areas of the bellows. During the melt injection phase the areas of the bellows have circular preform geometry. After the melt injection the hollow space is shaped by using the water injection process in combination with the melt push back procedure. This can be done on one hand exclusively with water or alternatively by using a projectile and WIT. As soon as the cavitation is completed, a controlled pressure decrease is carried out to realize a predefined cavity pressure value. If this is achieved, the automatic contour change of the preform to the final bellow geometry starts. This is realized by using the pressure-dependent control of volume flow rate. During the following controlled holding phase of the water pressure the cooling to the required demolding temperature of the polymer takes place. Finally the pressure drop and water return are carried out in order to demold the part waterless. Since end of 2011 the drain channel has been produced fully automatically with a two cavity mould.

Specific advantages are the stable and fully automated short process chain combined with extremely short cycle times and weight reduction due to the high integration of functions.



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