There is no abstract available for this thesis.

This creative project was undertaken to determine the effectiveness and possible usefulness of a small, laboratory sized plastic blow molder. The design of this machine was similar to those units used in industry but fabricated on a much smaller scale.The blow molder was of the vertical extrusion type. It was actuated by a hydraulic cylinder, and the plastic was melted by means of electric heating bands.The extruded plastic parison was formed by two matching mold halves, and air introduced through a needle valve to expand the hot plastic to the shape of the mold cavity.

This creative project involved an in-depth study of the transfer molding process and the engineering and fabrication procedures related to the development of a hand transfer mold. The investigator made a study of and constructed the equipment required for transfer molding a knife handle.The creative project outlines the compression molding process, describes the variations of the transfer molding process, and lists and compares the advantages and disadvantages of the compression and transfer molding processes. The creative project also suggests a series of operating instructions that may be used with the transfer mold.

This creative project involved the design and construction of a plastics blow molding machine for educational use. Many industrial machines were found which performed plastics blow molding but studies revealed that no equipment had been designed particularly for school use.This project covered all elements of the design of a plastics blow molding machine concluding with the construction of a working model. In this process a complete set of working drawings was developed as illustrated in this paper.The operation of the machine proved successful but with evidence that improvements could be made.

Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, Cape Town, 2004 / Most very large moulds are manufactured in Europe, especially in Germany and Italy. The main reason being that South Africa does not have enough very large size CNC machines on which these could be machined. A large size mould half can be split into two or more smaller parts for machining purposes and then reassembled later. In this way many large size moulds, especially rotational moulds can be manufactured on medium size CNC machines. Since the large component has been split into small parts, these can be distributed to different subcontractors to machine simultaneously, and thereby reducing the total manufacturing lead-time. The project then uses three case studies to advance the proposed concept for mould manufacture. A small size rotational mould for a model drum is manufactured to confirm that Pentech had both the infrastructure and required skill to make a rotational mould of any sort. Then a medium size rotational mould of a steering wheel is manufactured. This case study is the key and longest stage in this project; it consists of the full process of mould subdivision followed by full mould manufacture, some subcontracting of parts and lastly full product testing. Finally, a part of a large size mould was manufactured for purpose of investigating all aspects around the subcontracting ofmould parts. In the first case study the clamping strategy used through out as an integral part of the subdivision strategy is proven. The second case study using the medium size rotational mould successfully demonstrates the subdivision concept, along with its material savings. This second case study also introduces the idea of including CNC lathe parts. Lastly, the third case study using a large size rotational mould proves the contractibility of the mould segments using NC files, despite certain industry leaders believing that machine shops would not be interested in accepting work on the basis ofNC files

No description available.

No description available.

There is no abstract available for this thesis.

No description available.

In the extrusion blow molding process the shape and thickness distribution of the finished container depend on the dimensions of the parison at the time of inflation. In particular, the processes of swell and sag act to cause a variation of parison dimensions between the time the melt emerges from the die and the moment of inflation. / In the present study the effects of die geometry, extrusion velocity and the rheological properties of the resin on parison behavior were studied. Four annular dies (a straight, a diverging and two converging dies) and three high density polyethylene resins were used. To study the individual contributions of swell and sag to the overall parison behavior, two types of experiments were carried out. First, swell was studied in the absence of sag by extruding the parison into an isothermal oil bath. Both diameter and thickness swells were measured as functions of time. Then combined effect of swell and sag was studied by extruding the parison into an isothermal air oven. / A simple lumped parameter model was developed to predict the length of the parison using the swell data, storage modulus and process variables.