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Limiting Contradictions In A Photographic Paper Manufacturing Process

| On 16, Apr 2004

Introductions
Engineering systems, and particularly their associated production manufacture operations, are subject to limits in their fundamental capability. Understanding how and why these limits occur is an essential precursor to overcoming them. This article builds on previous work examining the limiting contradictions phenomenon and provides a graphic illustration of the dynamics of system evolution in action.

The focus of the article is the film coating process employed in the large-scale manufacture of photographic printing paper. The article plots the historical evolution of the process from its inception to the present day. Figure 1 provides a simplified summary of the overall process.

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The process is described in more detail in Reference 1. The theme of that paper was to describe the evolution of this paper coating process through the lens of contradiction emergence and resolution. Rather than repeat the content of that work here, we merely need to review the idea that improving the output capability of the process happens through a series of different design generations. As suggested by Figure 2, these generations may be observed as a series of s -curves. The Figure 2 image – reproduced Coating Drying Web Handling from Reference 1 – hides a considerable amount of detail. The aim of this paper is to expand the story of the evolution of the process by providing a more detailed analysis of how the system has changed since its initial inception.

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One of the main ideas of Reference 1 was that the evolution of the system happened through the resolution of a progression of different contradictions in which new ones emerge as existing ones become resolved. The story is complicated by the presence of the three different stages in the manufacture process. As is suggested by the history shown in the following table, it is possible to identify the speeds at which different parts of the process hit their respective limits.

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The table highlights the fact that each of the three different parts of the process has at one time prevented further increases in the speed of the process due to the emergence of a conflict – there was a desire to increase the s peed of the process, but something fundamental prevented that increase. In each case, further overall process speed increases only became possible once the emergent contradiction had been solved.

As reported in Reference 1, by way of example, when the process hit its limit at 8m/min, the drying process had hit its limiting contradiction as the length of building required to hold the festoons of paper became insufficient. The only way to obtain further increases in speed was if the contradiction could be s olved. As shown in Figure 3, the contradiction was solved by evolving a spiral-form dryer arrangement.

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In order to better illustrate the dynamics of the evolution of the manufacture process it is helpful to see the process via an animation.

Illustrations can be observed at the end of this paper. Essentially, the animation shows how different technologies reached their fundamental limits (reached the top of their s-curve), and how a new s -curve emerged once the limiting contradiction was resolved. This animation illustrates and provides the main purpose of this article.

As suggested by the final entry in the table, the current limit on the system is again back with the drying part of the process. Again also, the limiting contradiction is related to the length of the facility required to accommodate the current folded air-flotation design style. Anyone interested in examining possible next evolution steps may wish to explore some of the Inventive Principles illustrated in Figure 3.

References
1) Mitchell, I., Mann, D.L., ‘Overcoming Limiting Contradictions In a Continuous Manufacturing Process’, ETRIA TRIZ Future conference, Strasbourg, November 2002 (copies available from D.L .Mann upon request).

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