Quality control, statistical quality control, process control, total quality, are some of the phrases used to describe a function that varies considerably from one manufacturer to another and from one author to another. This paper attempts to review the changes in the concept of quality control that have resulted from the application of research programmes.
The historical scenario has three aspects. Just before the war an awareness was arising of the fact that paper was variable and that the variability had two components: along and across the machine. During the war paper had to conform to the same acceptance procedures as a raw material as did other military supplies. Thus the concept of statistical quality control was developed which, whilst recognising the need to relate property levels to the underlying variability, nevertheless used methods more adapted to discrete units of production rather than to a continous product.
It was not until after the war that major studies were undertaken, in the golden era of paper research, into the variability on the macro- and micro-scale of the paper product. This was the period of the awareness of the need for uniformity and freedom from mechanical defects, particularly in paper for high speed letterpress and gravure applications. The results of detailed study into the heterogeneity of the sheet prompted the development of instruments which would enable fundamental properties to be measured.
The result of two decades of fundamental work, not by the paper industry but by the process control industry, is the current situation of integrated measurement and control, which is described in some detail. Finally, the ability to know precisely what is being made has resulted in the concept of total quality.
Such a survey would not be complete without some reference to the development of product quality standards and specialised tests which relate to end user requirements. These, however, whilst constituting a major factor in the industry’s research programme, are, in the authors opinion, of less importance in comparison to the extraordinary developments in process control made by firms specialising in that function.
Acknowledgements are made to very many people throughout the
industry who have helped in this survey.