FoodChemTopics

THE "CONTINUOUS PROCESS" AND PACKAGING APPLICATIONS. PART ONE

Salvatore Parisi
Industrial Consultant


ABSTRACT
Nowadays, the packaging industries are obliged to face a serious energy crisis. As a result, most of the usual raw materials are difficult to find out with good quotations. It is well- known that the so-called "continuous process" is the best solution in reference to the maximization of profits. Naturally, the allusion is referred to the control of production costs. The above-mentioned procedure is diametrically opposed to the "discontinuous working". This opposition is apparently originated by the different speed of the two methods. In reality, the choice is normally directed to uninterrupted procedures in the industrial field. On the other hand, the discontinuous process is interpreted as a synonym of "manual" working. This distinction helps to recognize the importance of the economic result as the main indicator for project designers. In fact, a quantity of industrial managers is sincerely persuaded that the higher the productive pulse, the lower the percentage of rejected units. This description should provide a complete control on all the involved parameters. In other words, the total sum of raw materials should always give a group of objects with constant percentages on the total finished products. However, the industrial processes do not correspond to the idea of designers.
It has to be noted that the apparent failures of the continuous process are often manifest in the intermittent workings. Actually, these problems can be explained on a theoretical base, but some sort of practical example should be showed.
With concern to the packaging industry, the objective of this study was to explore all the "process discontinuances" in the continuous production. Some speculative approach is needed to be ready for the practical comprehension. Being the objective too hard to be realized in few pages only, this paper was subdivided in six subsequent issues.




THE DIFFERENCE BETWEEN CONTINUOUS AND DISCONTINUOUS PROCESS
The Industrial Revolution is known as a chaotic sum of technological and socio-economic changes. One of the best-known innovations was surely the penetration of the extensive mechanization. This historical circumstance turned the home-based hand manufacturing into large-scale factory productions 3,4.
Actually, the first "proto-industrial" productions were designed in a fragmentary way2. In other words, each item was obtained at the end of "an arrangement of workers, machines, and equipment in which the product passes consecutively from operation to operation until completed" 3,4,5.
So, a particular production - in which every product is a central unit continually modified with other different parts - should be clearly intended as the "stratification" of various operations.
In addition, every sub-process may be cause of production failures2. Consequently, the higher the number of different sub-operations, the higher the related failure risks. On these bases, any product of a determined batch is at least conceptually different in comparison with all the other items. All the industrial fields – including the packaging - are obliged to respect this tacit rule.
Basically, the limitation of a discontinuous process consists in the breaking and the fragmentation. This deficiency can be eliminated increasing the on- line quality control and reducing ideally all the wait times to zero. Nowadays, a quantity of industrial automatisms are able to self-manage themselves with different and fast inspection devices.
In fact, a quantity of industrial managers is sincerely persuaded that the higher the productive pulse, the lower the percentage of rejected units2. This description should provide a complete control on all the involved parameters. In other words, the total sum of raw materials should always give a group of objects with constant percentages on the total finished products. However, the industrial processes do not correspond to the idea of designers.
A typical example seems the production of polyvinyl-acetate- based food coatings2 (for cheese protection). The percentage of claimed failures (insufficient cheese transpiration, mould inhibition below normal standards, unpleasant “acetate” smells) is often variable and perhaps randomised. In fact, an ideal continuous process should not be able to generate similar situations.
Consequently, the operative definition of the continuous process is probably understandable if the problem can be evaluated by the opposite viewpoint. In other words, if a determined manufacture shows typical “discontinuous” failures, the “discontinuity” of the industrial process should be firstly examined and clearly defined.

THE DISCONTINUOUS PROCESS.
Apparently, the discontinuous process is temporally circumscribed by two fundamental moments2. The first step is the introduction of raw materials. The last moment shows the release of finished products with the mass of discarded pieces and by-products. Successively, the production line must be arrested to allow the upload of new raw materials.
However, the description of a discontinuous production is characterized by other peculiarities1:
a) a multidirectional route;
b) possible external interferences with the process flow;
c) presumable internal diversions;
d) the unavoidable variableness of the involved raw materials in terms of quality and quantity;
e) the discrepancies between the room conditions of the "test" process and those of the final installation;
f) the insufficient durability of mechanical devices.
These features are generally implicit in the concept of the continuous production but their inevitability has to be carefully recalled. This paper would individually highlight each one of these points before some practical examples are showed2.



REFERENCES
1. Anonymous, 2007. Can Coatings Measurement to Save Millions. Food Packaging Bulletin, 16(3), p. 8.
2. Parisi S., 2005. La produzione “continua” č anche “costante”? Confutazione di alcuni luoghi comuni nel settore industriale/ manifatturiero. Il Chimico Italiano, XVI, N.3/4, 10: 18.
3. The American Heritage Dictionary, Third edition 3.6 a , 1994. Softkey international Inc., U.S.A.
4. American Heritage  Dictionary of the English Language, Third edition, 1992. Houghton Mifflin Company. Electronic version licensed from and portions copyright  1994 by Infosoft International Inc., U.S.A.
5. E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil, 1988. The Dictionary of Cultural Literacy. Houghton Mifflin Company. Electronic version licensed from and portions copyright  1994 by Infosoft International Inc., U.S.A.