THE CONTINUOUS PROCESS IN THE PACKAGING FIELD. AN OVERVIEW Salvatore Parisi Industrial Consultant ITALY 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 ideality of designers. The difficult realization of "true" continuous workings is evident in every industrial field. With concern to the packaging industry, the objective of this study was to show some possible complications by the conceptual point view. Other papers will continue on this trail with detailed explanations and realistic examples. INTRODUCTION TO THE CONTINUOUS PROCESS 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. Consequently, the maximization of profits is strictly linked with the control of production costs1. The possibility of increasing of working speeds to the maximum level is often showed as the best way. The above-mentioned procedure is diametrically opposed to the "discontinuous working". This opposition is apparently originated by the different speed of the two methods2. 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. However, some sort of definition can be made for every type of process. In detail: 1. The "discontinuous" proceeding must be subdivided in two or more parallel and/ or rowed steps. These steps must be temporarily disconnected and the time extension of every break is not circumscribed. A discontinuous process can be connected with other workings if the first proceeding has one parallel step (diversion) at least. 2. The "continuous" proceeding can be subdivided in two or more theoretical phases. These phases are constantly connected on a single linear track and the time extension of every connection is literally infinitesimal. There is not possibility of parallel phases (diversions). A continuous process can be connected with other workings exclusively in the beginning and/ or at the end. The choice between the two possibilities is seriously difficult. As an example, the distillation of the atmospheric air can be carried out2 by the continuous way (Flash process) or by the interrupted method (Batch process). The only technical difference consists in the change of the air supply. On the other hand, the final aim is the same for each type of working. In spite of that, the productive demand influences heavily the final strategy. The Batch distillation is desirable if the air aspiration is not powerful enough to provide good flows. So, the flow regulation is obtained working on the separated constituents and the total cost can be lowered. On the contrary, the Flash process is more convenient than the interrupted distillation if the total production is very high2. The continuous recycling of the solutes at the end of the distillation column is powerful enough to justify the decision. The concept of "continuous production" can be illustrated in the above-mentioned way. Actually, the sum of raw materials should give a constant quantity of finished products group if the process is completely manageable. Unfortunately, this situation is clearly utopistic. In fact, every "ideal" proceeding, temporarily circumscribed in the beginning and at the end, provide constant yields. However, every designer knows that chemical and other industrial productions rarely repeat themselves in the preliminary (test) stage2. The best approximation is the correlation of the dispersion, D %, of the entering materials with the finished materials and the number of "pauses" on the flow line. In other words: NY% (Net Yield, %) = GY% (Gross Yield, %) - D% (Dispersion, %) (1) where: GY% = (Quantity of Finished Products)/ (Quantity of Raw Materials) ´ 100 (2) and: D% = (Quantity of Discarded Pieces)/ (Quantity of Raw Materials) ´ 100 (3) NY% (Net Yield, %) is fully predictable if GY% (Gross Yield, %) is known and D% is related by a correlation with the number of pauses. It has to be highlighted that every "dispersive" pause is linked to some deviation related to defected products. So, the key of the problem is the operative definition of the continuous process as a sequence of linked events without useless or detrimental deviations2. In addition, the conversion of a test process into new production lines implies often a quantity of important modifications in progress. It is well- known that all the industrial productions are completely manageable in our technological World. Unfortunately, this security is not really founded on convincing bases2. CONCLUSIONS The lowering of industrial costs is difficult to obtain. The commercial success is partially based on the control of production losses. In general, the so-called "continuous process" is seen as the best solution in reference to the maximization of profits. However, the practical execution is often forced to a series of unavoidable difficulties. The difficult realization of "true" continuous workings is evident in every industrial field. With concern to the packaging industry, the objective of this study was to show some conceptual complications. Other papers will continue on this trail with detailed explanations and realistic examples. REFERENCES 1. Anonymous, 2007. Can Coatings Measurement to Save Millions. Food Packaging Bulletin, 16(3), p. 8. 2. Parisi S., 2005. La produzione “continua” è anche “costante”? Confutazione di alcuni luoghi comuni nel settore industriale/ manifatturiero. Il Chimico Italiano, XVI, N.3/4, 10: 18.
THE CONTINUOUS PROCESS IN THE PACKAGING FIELD. AN OVERVIEW
THE CONTINUOUS PROCESS IN THE PACKAGING FIELD. AN OVERVIEW Salvatore Parisi Industrial Consultant ITALY 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 ideality of designers. The difficult realization of "true" continuous workings is evident in every industrial field. With concern to the packaging industry, the objective of this study was to show some possible complications by the conceptual point view. Other papers will continue on this trail with detailed explanations and realistic examples. INTRODUCTION TO THE CONTINUOUS PROCESS 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. Consequently, the maximization of profits is strictly linked with the control of production costs1. The possibility of increasing of working speeds to the maximum level is often showed as the best way. The above-mentioned procedure is diametrically opposed to the "discontinuous working". This opposition is apparently originated by the different speed of the two methods2. 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. However, some sort of definition can be made for every type of process. In detail: 1. The "discontinuous" proceeding must be subdivided in two or more parallel and/ or rowed steps. These steps must be temporarily disconnected and the time extension of every break is not circumscribed. A discontinuous process can be connected with other workings if the first proceeding has one parallel step (diversion) at least. 2. The "continuous" proceeding can be subdivided in two or more theoretical phases. These phases are constantly connected on a single linear track and the time extension of every connection is literally infinitesimal. There is not possibility of parallel phases (diversions). A continuous process can be connected with other workings exclusively in the beginning and/ or at the end. The choice between the two possibilities is seriously difficult. As an example, the distillation of the atmospheric air can be carried out2 by the continuous way (Flash process) or by the interrupted method (Batch process). The only technical difference consists in the change of the air supply. On the other hand, the final aim is the same for each type of working. In spite of that, the productive demand influences heavily the final strategy. The Batch distillation is desirable if the air aspiration is not powerful enough to provide good flows. So, the flow regulation is obtained working on the separated constituents and the total cost can be lowered. On the contrary, the Flash process is more convenient than the interrupted distillation if the total production is very high2. The continuous recycling of the solutes at the end of the distillation column is powerful enough to justify the decision. The concept of "continuous production" can be illustrated in the above-mentioned way. Actually, the sum of raw materials should give a constant quantity of finished products group if the process is completely manageable. Unfortunately, this situation is clearly utopistic. In fact, every "ideal" proceeding, temporarily circumscribed in the beginning and at the end, provide constant yields. However, every designer knows that chemical and other industrial productions rarely repeat themselves in the preliminary (test) stage2. The best approximation is the correlation of the dispersion, D %, of the entering materials with the finished materials and the number of "pauses" on the flow line. In other words: NY% (Net Yield, %) = GY% (Gross Yield, %) - D% (Dispersion, %) (1) where: GY% = (Quantity of Finished Products)/ (Quantity of Raw Materials) ´ 100 (2) and: D% = (Quantity of Discarded Pieces)/ (Quantity of Raw Materials) ´ 100 (3) NY% (Net Yield, %) is fully predictable if GY% (Gross Yield, %) is known and D% is related by a correlation with the number of pauses. It has to be highlighted that every "dispersive" pause is linked to some deviation related to defected products. So, the key of the problem is the operative definition of the continuous process as a sequence of linked events without useless or detrimental deviations2. In addition, the conversion of a test process into new production lines implies often a quantity of important modifications in progress. It is well- known that all the industrial productions are completely manageable in our technological World. Unfortunately, this security is not really founded on convincing bases2. CONCLUSIONS The lowering of industrial costs is difficult to obtain. The commercial success is partially based on the control of production losses. In general, the so-called "continuous process" is seen as the best solution in reference to the maximization of profits. However, the practical execution is often forced to a series of unavoidable difficulties. The difficult realization of "true" continuous workings is evident in every industrial field. With concern to the packaging industry, the objective of this study was to show some conceptual complications. Other papers will continue on this trail with detailed explanations and realistic examples. REFERENCES 1. Anonymous, 2007. Can Coatings Measurement to Save Millions. Food Packaging Bulletin, 16(3), p. 8. 2. Parisi S., 2005. La produzione “continua” è anche “costante”? Confutazione di alcuni luoghi comuni nel settore industriale/ manifatturiero. Il Chimico Italiano, XVI, N.3/4, 10: 18.