Statistical Process Control in Iron Ponder Production and New Product Development

S PC is SPC is discussed with a view to indicating its implications not only to manufacturing and quality but to research and product development as well. In the manufacturing/quality area, the efforts and methods attending full-scale implementation of SPC are briefly reviewed with special reference to the differences inherent in powder making versus manufacturing of parts. SPC charting techniques suitable for powder making are described and discussed. In the product development area, it is shown how SPC influenced a major research program. The objective of the program was to improve premixed products with a view to reducing variability in parts manufacturing. ANOVA studies of production mixes generally showed that the main sources of premix variability were mix to mix differences and within mix differences arising from demixing subsequent to premix manufacture. It was recognized that SPC is especially applicable to dealing with the first of these and subsequent efforts to implement it to premixes are described. In the case of demixing, the developments of a new premixing process is reported in which the alloy admix ingredients are bonded to the iron. The general findings of extensive studies, which show the benefits of the new process in terms of reduced variability in parts manufacturing, are reviewed and the results of a study of a FC-0208 premix are presented as an example. SPC theory and concepts are used to indicate the significance of the results and their potential applicability to the production of parts. INTRODUCTION Statistical process control is having a profound effect on manufacturing and quality control in the P/M industry. Its effects, however, are not limited to these functions. It is also influencing research and product development. The purpose of this paper is to report experiences with SPC in each of these two areas. Since different issues are addressed in each case, the paper has been divided into two parts. In a previous paper, the challenges and problems inherent in adapting SPC techniques to a process industry, notably steel powder manufacturing were discussed. (l) The statistical charting techniques best suited to this process are not always the same as those best suited to structural parts manufacturing. Therefore, there is a need for a dialogue to reach a mutual understanding of these differences. Part I of this paper will briefly review experiences in the early implementation of SPC and expand the discussion to include the specific charting techniques which were found most