Surface Quality and Dimensional Accuracy of Gypsum Bonded Investment Flask Casting Moulds

Kerem Altug Guler; Mustafa Cigdem

doi:10.3139/120.110262

Article

Surface Quality and Dimensional Accuracy of Gypsum Bonded Investment Flask Casting Moulds

Kerem Altug Guler and Mustafa Cigdem

Published/Copyright: May 26, 2013

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From the journal Materials Testing Volume 53 Issue 9

Abstract

In this study surface finish and dimensional charactersitics of castings produced with gypsum bonded block investment moulds were investigated. Commercial and laboratory made gypsum bonded investment moulds were used for investment casting mould making. To compare the casting quality of the investment powders, wax patterns for surface roughness specimens and linear dimension measurement specimens were designed and produced with special geometry. Wax trees were assembled with these patterns, cylindrical stainless steel perforated flasks were settled around the trees and gypsum bonded investment slurries were filled into flasks. Conventional tin bronze and sterling silver were subsequently cast into these moulds by vacuum assisted and vacuum pressure casting processes, respectively. Afterwards, surface roughness of specimens were measured and linear dimensions of wax patterns and cast specimens were compared to determine percentage of dimensional change.

Kurzfassung

Für die diesem Beitrag zugrundeliegende Studie wurden die Oberflächenbeschaffenheit und die Maßgenauigkeit von Gussteilen, die mittels gipsgebundener Blockfeingussformen hergestellt wurden, untersucht. Hierfür wurden kommerziell und im Labor hergestellte Formen verwendet. Um die Gussqualität der Feingusspulver zu überprüfen, wurden Wachsmodelle der Proben zur Ermittlung der Oberflächenrauigkeit und Messung der linearen Abmessungen konstruiert und hergestellt, die eine besondere Geometrie aufwiesen. Wachsbäume wurden mit diesen Modellen zusammengefügt, perforierte Kolben aus hochlegiertem Stahl wurden um diese Bäume angeordnet und gipsgebundene Gießschlicker wurden in die Kolben eingefüllt. Konventionelle Zinnbronzen und Sterlingsilber wurden nachfolgend in diese Formen gegossen, wobei der vakuumunterstützte und der Vakuumdruckgussprozeß angewendet wurden. Danach wurde die Oberflächenrauigkeit und die linearen Abmessungen der Wachsmodelle gemessen und es wurden die Gussteile hinsichtlich der prozentualen Veränderungen der Abmessungen verglichen.

Kerem Altug Güler was born in 1981, he is a research assistant at the Yildiz Technical University since 2004. He received his master degree from the Yildiz Technical University Metallurgy and Materials Engineering Department in 2005. He is also co-researcher in Balkan Centre of Advanced Casting Technologies (BCACT). Presently, he is a Ph.D student and working on investment casting.

Mustafa Cigdem was born in 1964. He is a Professor of Metallurgy and Materials at the Yildiz Technical University since 2000. He graduated as a metallurgical engineer from Istanbul Technical University in 1985. He received his master degree (M.Phil.) and Ph.D. in Metallurgy and Materials Science, in 1988 and 1990, respectively, both from the University of Birmingham, England.

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Published Online: 2013-05-26

Published in Print: 2011-09-01

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https://doi.org/10.3139/120.110262