Shell improvements for the investment casting of orthopaedic implants

Dooley, Gavin (2017). Shell improvements for the investment casting of orthopaedic implants. University of Birmingham. Ph.D.

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Abstract

This project focuses on understanding and improving the technology used in the ceramic processing of the investment casting of orthopaedic implants. The shell making process is a time consuming and costly stage of the Investment casting process. This work reviews the use of a super absorbent polymer as a means to decrease lead time within the shell room and improve capacity. The technology allowed a typical shell which had 2 hours dry time to be reduced by 75% to 30 minutes between coats. Following initial analysis, a greater understanding on the flaws of the Rapid Shell system was sought.

Work was also conducted to improve and understand the parameters which affect a generic shell system. Changes to the raw material were reviewed by changing the particle size of stucco and flour materials to improve strength. Different processing methods were also analysed to gain a better understanding into the fundamentals of ceramic processing. The use of rainfall and fluid bed stucco applications were analysed within a DOE experiment to better understand the effect of changes in microstructure affecting the overall performance of the shell. The results showed the microstructure varied greatly between processing method which in turn affected the thickness and strength of the respective shell systems. Rainfall sanded shells exhibited a thinner stucco layer while the flexural strength was 20% higher than fluid bed shells.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):