Improving Reliability of GD&T Evaluations Using Portable Measuring Systems

Publication Details

Abstract

GD&T is an engineering drawing language establishing consistent communication between design intent, manufacturing, and inspection. Book examples of the inspection are often illustrated by fitting parts within physical gages, and using dimensional measurements with no uncertainty. This paper pertains to the inspection using portable measurement equipment, often with slight but noticeable measurement uncertainty. The impact of uncertainty on determining conformance / non-conformance often depends on how those measured values are determined. This paper examines several common methods and works toward reliable methods of using measurements with noticeable measurement uncertainty. The methods for include: data set size, averaging of multiple measurements, guard banding, and localized measurements. The paper concludes that localized averaging within feature boundaries reduces measurement noise and improve reliability, though not foolproof, inspection method for GD&T evaluations.