Quasi-Kinematic Couplings for Low-Cost Precision Alignment of High-Volume Assemblies

Abstract

Quasi-kinematic couplings (QKCs) are alignment devices that incorporate elastic-plastic deformations to combine principles of elastic averaging and exact constraint to achieve precision alignment. This paper shows QKCs can be used for low-cost alignment in high-volume assembly applications. This is demonstrated via a case study of the process used to align main journal bearings in an automobile engine. Results of experiments show best case QKC performance of 0.35 microns compared to 4.85 microns for the widely-used dowel pin-hole design. Statistical analyses predict the QKC will meet five micron alignment requirements in 99.999 percent of all assembly cycles. Compared to the dowel pin-hole design, the QKC uses 60 percent fewer piece parts and costs 36 percent less.