Masters Theses

Abstract

"Gating and mold filling of castings in the lost foam casting process have been studied to determine the importance of processing parameters and how these parameters can be used to control mold filling. The research in paper 1 describes the statistically significant effects of processing parameters and gating system design for an industry-type hat-shaped pattern on mold filling characteristics such as fill time, horizontal velocities, and vertical velocities. The permeability of the refractory coating is the most important variable. The metallostatic pressure head and the pouring temperature also affected the mold filling characteristics to a smaller degree. A maximum velocity (about 1 in./s.) cannot be exceeded if a sound castings is to be produced.

Paper 2 describes how processing parameters might be used to predict and control the mold filling in the lost foam casting process. The research involved four steps. Step 1, which used a pattern for a tube holder for a heat exchanger (the pendant pattern), explored ways to force the pattern to fill faster than the runner and to skew the progressing metal front towards the gates in order to force any foam decomposition products into the gating system. Although some improvements were made, this was only accomplished when a straight plate pattern was substituted for the curved pendant pattern.

Step 2 used the information from step 1 and previous work to produce a model which predicted the position of the molten metal front throughout the filling process of a pump housing pattern. It was found that intersections involving sharp direction changes from vertical to horizontal flow have a sizable effect on the velocity of the molten metal front as the pattern fills. The slope of the line, when actual time was plotted versus the expected time, also differed because the actual pattern had a higher density than those used to produce the model.

Step 3 explored in more detail the effect that sharp direction changes have on mold filling characteristics in simple plate patterns. The effect of the intersection on the flow of the molten aluminum was confirmed. The change in velocity was measured as a jump in the elapsed time when plotted against the predicted time.

Step 4 included the effect of the intersection on the predicted metal front progression in an industry-type pipe pattern casting. The predictions were not confirmed, suggests that the effect of intersections is more complex expected. More research on the effect of direction changes must be performed in order to make a model that accurately predicts mold filling in the lost foam process"--Abstract, pages iv-v

Advisor(s)

Askeland, Donald R.
Ramsay, Christopher W.

Committee Member(s)

Nyamekye, Kofi

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Publisher

University of Missouri--Rolla

Publication Date

Spring 1995

Journal article titles appearing in thesis/dissertation

  • Statistically designed experiments for mold filling in the lost foam casting process
  • Prediction and control of the mold filling process in the lost foam casting process

Pagination

xxiii, 116 pages

Note about bibliography

Includes bibliographical references.

Rights

© 1995 Mickey Dean Lawrence, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Thesis Number

T 6947

Print OCLC #

32918365

Electronic OCLC #

1098177697

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