Hybrid moldings

An aqueous solution of salt monomer 9PME was mixed with tetramethoxysi-lane, yielding a gel, which was then vacuum-dried forming a precursor powder composed of silica gel and the salt monomer. This was subjected to high-pressure polycondensation under 235 MPa at 230 °C for 5 h, producing polyimide-silica hybrid molding. By varying the ratio of tetramethoxysilane to the salt... 

The processing steps of CNP are very simple. The hybrid mold is first imprinted into the resist layer by pressure, then the whole mold-substrate assembly is exposed by UV radiation (Fig. 8B). After the hybrid mold and the substrate are separated (Fig. 8C), the substrate is immersed in a developer solution to remove... 

Fig. 8 Schematic of the CNP technique using a hybrid mold. (View this art in color at www.dekker.com.)...

The effect of implementing hybrid mold temperature dependant heat characteristics on the accuracy of 3D injection molding simulation... 

When analyzing the thermal behavior of hybrid molds, normally fixed values for thermal characteristics are implemented. This paper will discuss the underestimated effect of temperature dependant heat characteristics of hybrid mold materials on the accuracy of 3D injection molding simulation via obtained results of a former PhD work and implementation of this knowledge into Moldex3D (M3D). 

As with conventional molds, mold cooling is one of the most important characteristics affecting the cycle time during the injection molding process. Prediction of the thermal behavior of hybrid molds is complicated, since different mold steel materials are used in combination with one another, such as standard 1.1730 steel and RT alloys. 

To analyze and predict these problems, FE techniques have been integrated into mold design procedures. The results are compared with the data derived from the experimental hybrid mold, to aid the optimization of conduction, convection and radiation boundary conditions of the hybrid mold [3]. 

When analyzing the heat characteristics of different mold materials, some very important results are obtained. Figure 2 illustrates the temperature dependant heat diffusivity for some hybrid mold metal alloys. 

As already mentioned, conventional mold design assumes solid steel tooling. Hybrid molds use standard mold frames incorporating RT inserts. The thermal behavior of these combinations of materials is little understood. 

The frame of the hybrid mold has been produced by use of standard 1730 steel. Both mold core and cavity are produced using the DMLS DS50 method. Based on conventional injection parameters for both amorphous and crystalline polymers, the mold has been analyzed by verified FE analyses. After mold design and FE model setup, all boundary conditions were implemented. The model was solved using steady state and transient solver control, by use of the Jacobin solution method and the quadric solver with Chebychev accelerator [5]. 

Currently, new projects on the use of hybrid molds as for also blow molding are started. The obtained results of the hybrid injection molds will be integrated. 

Injection molds, Rapid Prototyping, Rapid Tooling, Hybrid Molds, Design strategy. 

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