Assessment of Measurement Systems for the Dimensional Inspection of Investment Castings

摘要

The performance of widely used dimensional inspection equipment and systems used forinvestment casting dimensional inspection has been studied. Factors that influence dimensionalvariability have been identified and compared to the current investment casting dimensionaltolerance guidelines. In addition the role of tooling allowances and first-article inspectionpractices on assuring dimensional conformance have been established.The poor dimensional repeatability and reproducibility of hand-held inspection devices,even when used by experienced operators, suggests that these measurement devices are oflimited use by investment casters. Coordinate measuring machines (CMMs) have improveddimensional repeatability and reproducibility. However, even the use of CMMs requires carefulinspection strategies for success. First-article inspection strategies to minimize centering errorsare also described. An overall picture of the relative influence of process and measurementfactors influencing the dimensional conformance of investment castings will be presented.