Development of a new crimp-quality-monitoring system for manually operated tools

This thesis is concerned with the development of a novel technical solution that is aimed to improve the quality of cable crimp terminations in the electronics industry. The automotive, aero and military vehicle industries are of special interest due to their stringent requirements for guaranteed quality assurances in relation to their safety-critical products. The emphasis is on handheld crimping tools, where a new scheme for measuring the relevant crimp force is proposed using a small embedded computer to process information; so as to make an on-instrument statement regarding the crimp process quality. The thesis includes a detailed review of the current technical practices in the cable termination business, with a particular emphasis on the quality estimations for crimped connections using the crimp force monitoring (CFM) scheme. A comprehensive study of the state-of-the-art crimp force monitoring schemes and technologies is presented. A gap in the tool chain is identified whereby the industry has a preference for the use of hand tools in some selected processes; but the CFM scheme cannot be currently integrated directly with such hand tools. The bulk of the work in this thesis is thus focused on the development of a technical solution that will address this need for integration of hand tools with the CFM scheme. The concept is to develop a fully embedded subsystem that can be attached directly to a hand tool and this system will perform all of the signal processing and the statistical analysis so that each crimped joint can be trusted to meet the relevant stated quality parameters. In the course of development work a fully functional prototype subsystem is developed for the CFM solution, for application to hand tools. Analytical and statistical measurement and assessment algorithms were developed to a standard, which allows a final quality rating to be applied to crimped joint connections. Such algorithms are designed to be embedded directly onto the instrument’s microcomputer. The new system has been evaluated and tested in the course of this research project and it has currently been accepted by a number of industries for a planned volume qualification assessment.