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Integrated high-temperature (HT) ultrasonic sensors have been developed successfully by using piezoelectric bismuth titanate and lead zirconate titanate films HT ultrasonic transducers for real-time, non-destructive, and non-intrusive diagnosis of polymer injection molding (IM) processes. The HT ultrasonic sensors can be integrated onto the barrel and/or mold of IM machine, according to the customer's requirements. These sensors can be operated up to 400°C without cooling system and ultrasonic couplant, and can be miniaturized with sufficient signal strength and signal-to-noise ratio. / The chosen IM processes are grouped to large- and small-scale 1M processes. The large-scale ones include conventional IM, co-injection molding (COIM), and fluid (gas/water) assisted injection molding (GAIM/WAIM). A filling incompleteness of 1 volume-% for IM of polycarbonate (PC) part, the core (PC) material movement and layers dimensions for COIM, the fluid motion, thickness and deformation of the hollowed high-density polyethylene (HDPE) part for GAIM/WAIM were diagnosed during processing by ultrasonic sensors and techniques developed. / The small-scale ones include IM for microfluidic device (IMMF) and micromolding (MM). The optimization of holding pressure for producing a flat polymethyl methacrylate (PMMA) part (surface roughness < 5 mum) having micro structures for IMMF, estimation of temperature of polyacetal copolymer (POM) melt in the barrel and filler concentration of nylon 66 (PA66) mixed with polyhedral oligomeric silsesquioxanes (POSS) part in the mold for MM, and evaluation of thickness variation of molded alumina ceramic powder part for MM were demonstrated. The melting stages and quality of low-density polyethylene (LDPE) in the barrel has been successfully monitored using ultrasound. The important phenomena during melting processes, such as partially melting pellets, air bubbles, melting completeness, and effects of melting temperature and rotation speed have been diagnosed by ultrasonic signatures. / These diagnostic results verify that the developed integrated HT ultrasonic sensors and techniques are capable of monitoring various IM processes to fabricate parts and products having complex formation, tiny size and micro structures, and evaluating the part quality in order to provide timely information for process optimization.

Thesis (MEng (Industrial Engineering))--University of Stellenbosch, 2006. / This thesis represents the results of a study for the use of conformal cooling in blow mould design. As a part of this, design case studies and comparative experiments were conducted to determine the difference in performance of blow moulds incorporating conventional cooling and those with conformal cooling. The cooling configurations are compared using simulation to identify the shortcomings of conventional cooling. In addition modern manufacturing methods able to manufacture complex conformal cooling designs, are evaluated. The relevant cooling principles are explained using mould designing handbooks as well as heat flow handbooks. The tie between them is made and the differences explained. The moulding cycles of injection as well as blow moulding process are explained and the applicable simulation software used in these fields is described.

Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 2003 / Injection moulding is a process by which molten polymer is forced into an empty cavity of the desired shape. At its melting point, polymers undergo a volumetric expansion when heated, and volumetric contraction when cooled. This volumetric contraction is called shrinkage. Once the mould cavity is filled, more pressure is applied and additional polymer is packed into the cavity and held to compensate for the anticipated shrinkage as the polymer solidifies. The cooling takes place via the cooling channels where the polymer is cooled until a specific ejection criterion is met. Heat from the polymer is lost to the surrounding mould, a part of this heat reaches the cooling channel surfaces, which in turn exchange heat with the circulating cooling fluid. Due to the complexity of injection moulded parts and the cooling channel layout, it is difficult to achieve balanced cooling of parts. Asymmetric mould temperature distribution causes contractions of• the polymer as it cools from its melting temperature to room temperature. This results in residual stresses, which causes the part to warp after ejection. Given the understanding of the mathematical model describing the heat transfer process during the cooling stage, the objectives of this study were three fold. Firstly, an alternative numerical model for the heat transfer process was developed. The proposed model was used to investigate the cooling stress build-up during the injection moulding process.

TSDC (thermally stimulated depolarization current) is one of the most important and popular technique for investigating electret materials. TSDC technique can indicate the magnitude of polarization and depolarization, relaxation time, charge-storage, glass transition, and activation energy. To fully investigate polarization and relaxation for pure epoxy and filled epoxy materials, a TSDC system was built and verified by the research. The article describes the building processes and verification of the TSDC system. TSDC, TSPC, and TWC tests data for epoxy and filled epoxy samples are presented in the article. To compare TSDC technique with other related techniques, DEA (dielectric analysis), DMA (dynamic mechanical analysis), and DSC (differential scanning calorimetry) tests are introduced.

The aim of the master’s thesis is to design continuous mixer for preparation of molding compounds on the performance of 1 – 3 t/hour. The first part of the thesis contains recherché from molding compound and molding compound mixers field. In the next part there is an own design of mixer containing basic calculations and strength analysis by FEM. Part of the thesis is also 3D model of the whole machine as well as drawing documentation of selected parts. At the end of thesis partial risk analysis by FMEA is made.

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Yes / Polypropylene (PP) reinforced with 2 and 4 wt% of multi-walled carbon nanotubes (MWNT) were melt-blended in twin screw extruder and then molded by compression or micromolding process. The impact of injection speed on the surface morphology, rheological and tensile characteristics was investigated by using a scanning electron microscope, parallel plate rheometry, and tensiometry. Results showed that the tensile properties of micro-molded specimens were remarkably higher than those of the compression molded sheets. Compared to compression molded sheets, micromolded specimens demonstrated up to 40 and 244% higher tensile stiffness and yield strength, respectively, most likely due to the alignment of polymer chain segments in the flow direction induced during the micromolding process. It was observed that the fast filling speed caused a drop in the tensile properties of the nanocomposites and polymer. Rheological examination revealed that the presence of a rheological percolation network in the nanocomposites produced by micromolding and the fast injection speed was beneficial for establishing the percolated network. Morphological examination revealed that the size of nanotube agglomerations that appeared in micromolded specimens was up to five times smaller than in compression molded sheets and the agglomeration size decreased with the increase of the injection speed.

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