Variability of Niyama Values Study

University of Iowa/MTI Study of the Variability of Niyama Values Available from Commercial Software

The Materials Technology Institute showed interest in this project with the University of Iowa - Yield program. In particular members of MTI have focused on the Gage R&R study of radiographic film interpretation. The MTI members will often require that castings be radiographed to ensure quality levels are delivered. However, they have continued to look at the issue of casting quality and established a Task Group to examine how they can better specify casting quality. The UI work on leakers has aroused great interest at MTI to the extent that they wish to see how simulation may be included in their own purchasing specifications and possibly incorporated in ASTM and ASME standards and codes. There are already precedents for the requirement of solidification simulation by purchasers.

Clearly different software packages calculate Niyama values at different points during solidification and use different units. There are other variables which must also be considered in the modeling of solidification that are foundry dependent. In order for the use of solidification simulation to be used by purchasers, there is a need to determine the variability that may be expected in the results so that unreasonable requirements that do not benefit the purchaser are avoided.

The attached documents describe the rationale and requirements of the study. The intent is to determine the variability in the Niyama values, it is not to see how good a foundry is at risering a casting. The "stl" files are available below. Although four alloys are shown, it is not necessary for each foundry to simulate all four of the alloys.

Doc Pkg.pdf
Documentation package
Cover letter, Niyama Round-Robin description, and data sheet to fill out and email back.
Cover Gage RR-1.pdf
Cover Letter
Describes the need for the Round-Robin study.
Niyama Round-Robin Description.pdf
Description of the Niyama Round-Robin study.
Background and objective of the study, description of the CAD files, simulation procedure, preparation of the results, checklist of the simulation results to be returned and a copy of the simulation data sheet.
Data Sheet to Fill Out and Email.doc
Simulation data sheet
Simulation data sheet to be filled out and returned, in Microsoft Word format.
Data Sheet to Fill Out and Email.pdf
Simulation data sheet
Simulation data sheet to be filled out and returned, in PDF format.
Mold box geometry
Riser geometry
Valve geometry
Valve and riser geometry together - no longer available, use individual files above.
IGES file containing the combined geometries of the Niyama valve with the riser and contact all in one solid model. (Compressed in .zip format)