Derecel‹ hassas döKÜm yüzey kal‹tes‹ ve boyutsal hassas‹yet
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- Bu səhifədəki naviqasiya:
- Prof. Dr. Mustafa C‹GDEM
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Anahtar Kelimeler: Dereceli hassas döküm, boyutsal hassasiyet, yüzey kalitesi
YILDIZ TEKN‹K ÜN‹VERS‹TES‹ FEN B‹L‹MLER‹ ENST‹TÜSÜ 17 ABSTRACT THE FACTORS EFFECT DIMENSIONAL ACCURACY AND SURFACE QUALITY IN THE INVESTMEN CASTING Kerem Altug GULER Department of Metallurgical and Material Engineering PhD. Thesis Advisor: Prof. Dr. Mustafa C‹GDEM Investment casting is one of the important modern manufacturing technique and its prior applications are dating back to ancient times. Investment casting technique is used for fabrications of complex shaped components or hard metals and alloys which are difficult to produce with machining. The precision of the technique comes from disposable pattern. Generally patterns are made from wax or similar polymer based material which have low melting point and can be easily shaped. Patterns are removed from moulds with melting and there is no parting line on the cast parts. Depending on the pattern and mould materials, dimensional accuracy and surface quality of the investment casting is significantly higher than conventional sand casting process. Investment casting is a net or near net shape process so it minimize the further processes. There are two types of investment casting; investment shell mould casting, investment flask mould casting (block mould). In the shell mould process, pattern trees are covered with ceramic layer by layer to form a solid shell around the patterns. In the flask mould process, cylindrical hollow metal flasks are used for mould making. The flask is placed around the pattern tree and ceramic slurry is poured into it. The main uses of the investment flask moulds are jewellery and oral prosthesis castings. In this study, determination of moulding procedure and development of plaster bonded and high alumina cement bonded investments to produce castings with high dimensional accuracy and surface quality were aimed. Laboratory made and commercial investments were used for casting experiments and effects of several parameters on the dimensional accuracy and surface finish were investigated with characterization tests. Plaster bonded investments are used for especially jewellery castings are referred for relatively low melting point (< 1200 °C) metals and alloys. In the laboratory conditions plaster bonded investments were developed with similar characteristics to the commercial ones and successfully used. The investments which are appropriate to the high melting point (> 1200 °C) castings are generally phosphate bonded ones. These mould materials are used for also jewellery and dental castings for many years. High alumina cement bonded investments are an alternative to the phosphate bonded investments. High alumina cement was produced in the laboratory conditions and this bonding component is used for developing new investments and their characteristics were compared with commercial phosphate bonded investments. 18 In the results of the experimental studies first, development of the plaster bonded and the high alumina cement bonded investments that is the main aim of the thesis was successfully realized. The factors effects the surface quality and dimensional accuracy in the flask mould investment castings were largely determined and introduced with reasons. As a further work, study can be carried to modify and develop the morphologies of the bonding components. Yüklə 1,32 Mb. Dostları ilə paylaş:
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