The standardisation of process control for CNC manufacturing

Survival of modern day manufacturing firms depends on providing high quality, customised, and cost-effective products to customers. Thus consistent manufacturing of quality components has become pertinent. This has made process control in manufacturing systems essential. The existence of various standards and irreversible data conversion systems in the state-of-the-art CAx systems has led to heterogeneous information and loss of accuracy and context in production and measurement. This is major reason for the absence of process controlled manufacturing systems. In this paper the authors envisage the STEP-NC (ISO 14649) standard as an enabler for achieving standardised process control. This is due to its information models providing seamless integration among product models and manufacturing process models. This research investigates the STEP-NC suite of standards and subsequently presents the information data models of a standardised process control system (SProCS). The architecture of SProCS is presented and a prototype is realised for CNC manufacturing of prismatic components. The developed SProCS prototype uses statistical techniques and intelligent algorithms to analyse measurement results. This provides feedback in the form of corrective values and actions for process deviations to preceding levels in the manufacturing CAx chain. The authors have introduced a compensation scheme based on the process mean and variance shift derived from the statistical tests applied to the measurement results. The paper concludes by evaluating the performance of the prototype using a case study.