Product Description
PaperID: 1011
EventID: 20
Author: Sam N. Ramrattan, Ph.D., Western Michigan University
Abstract:
Dimensional accuracy of investment shells made from refractory ceramic media is a critical requirement during the casting and solidification process. Expansion and plastic deformation of the shell wall is a cause of dimensional defects in investment casting. Monitoring and circumventing the root cause of investment shell wall deformation can enhance investment cast quality. This study looked at the thermo-mechanical behavior of a disc shaped investment shell specimen, by means of an improved thermal distortion tester (TDT) developed at Western Michigan University.
The device can accommodate a 50 mm disc-shaped investment shell specimens of varying thicknesses. The specimen is automatically brought into direct symmetrical contact with a hot surface. The machine applies a ramping force to the specimen which represents a hydrostatic head pressure experienced by an investment shell wall during filling. Further, the machine maintains a constant force signifying filled mold through casting solidification. During this time the instrumentation is designed to capture the thermal gradient, the longitudinal and the radial movement in the specimen in real-time.
Measurement data from an investment shell material was collected and analyzed. The results are thermal distortion curves (TDC) that reveal dynamic behavior of the specimen that is critical in achieving sound dimensional characteristics in investment castings. The methodology can be used to establish a process control program and for predicting the behavior of the investment casting shell materials.
Keywords: Quality Control & Defects
Paper Pages: 16
Paper Year: 2015
Paper Index: 12:57
Paper Source: 82
