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Machine Specification and Build Issues — Risk Analysis — Process
Chapter 23
Machine Specification and Build Issues — Risk Analysis — Process 23.1 INTRODUCTION If we start by making the assumption that we are working with a worse-case scenario. If we use the scenario that someone has had an idea for a new product and has to take it forward through to production. The process has not been done before and hence the production machine cannot be an offthe-shelf design. Consider that even for a fairly standard metallizer it is probably a 1-year long task, from the point of writing a machine specification then choosing a supplier through to accepting the machine on site [1]. In our case to the time would follow a typical timeline as shown in Figure 23.1 that shows that for most projects the time from idea to production is greater than 3 years and for many cases is often more than 4 years. Some of this time is the natural time taken to do the initial research and development sufficient that a well-written specification can be produced. All too frequently, quite a lot of time is lost around the decision points. Particularly in large companies where many people and decision makers have to be involved to get all the necessary approvals. Rarely are decision points included on the critical path but they ought to be included as they delay any project as much as any late delivery of critical components. It is very common to underestimate the time required to get to the point of production. So many of the items included in the timeline appear on the critical path but are controlled by others who may not be working to the same deadlines or with the same enthusiasm as the owners of the project. The other aspects of developing a new product are to make sure there is a market for the product and also to make sure the market is ready to accept it when it becomes available [2]. It is essential that any market plans are developed in parallel with each and every new product [3 5]. If there is a lack of a market it may need to be developed otherwise there is the risk of the project being stopped.
Vacuum Deposition onto Webs, Films and Foils. DOI: http://dx.doi.org/10.1016/B978-0-323-29644-1.00023-2 © 2015 Elsevier Inc. All rights reserved.
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SECTION | 4
Idea
R&D 1 – 2 years
Pilot production
6 Months
Develop machine spec. 6 Months
3 Years + Acceptable new design
Identify preferred supplier
6–12 Months
Machine shipped Re-commissioned Start of production
3–6 months
3 Months
Machine built Commissioned & accepted
FIGURE 23.1 A typical timeline showing the time from idea to production.
23.2 RISK ANALYSIS — PROCESS It is common for processes developed on a small vacuum system to be scaled up without any thought to the possibility of failure of the process. Often a process will have been developed to a point where the envisioned product can be produced. However, the process will not have been optimized. In demonstrating the “proof of principle” of the process any variations in the process and the product outcome will usually have been ignored as being due to the lack of control available on the system. There are two possible sources of the variations. The first is that the variations are due only to the lack of control. The second possibility is that the variations are caused by a variable or a number of variables that not only are not being controlled but are also not even known about. If the process is not well understood then changes that are made during scale-up could be damaging if not catastrophic to the process. Additional work to understand and reduce the risk is much cheaper if carried before the system is built than after it is built. After it is built the costs for not running production are far higher than the cost of additional development prior to the system being designed and built. It is also cheaper to build the system with the correct process than it is to try to modify it once it has been built. A full understanding of the process in all its fine detail will enable a more detailed and more precise specification to be written. This will make the building and acceptance process of the system easier and should minimize any disputes on interpretation of the specification (Figure 23.2). The risks may be small such as for the deposition of a metal from an evaporation source. There is a body of information that is already available about a number of evaporation sources and on systems that have been built up to 4 m web width. Hence most of the information can be pieced together or
Machine Specification and Build Issues Chapter | 23 System complexity 1 Basic metallizing
Process risk
431
Manufacturer risk
1 Established process
1 Established manufacturer + proven experience with specials
3 New process, known materials & established system design
3 Young Co. built some machines inc. one special proven basic skills
2 Metallizing + plasma clean 3 Single layer oxide deposition 4 Single layer oxide + plasma clean 5 Single drum metal + oxide 6 Single drum metal + oxide + plasma 7 Two drum mixed metal + oxide
7 New process, known materials, new 7 Young Co. limited experience, built system design, some background info some machines but still learning
8 Two drum metals + oxides + plasma 9 Multi source + multi drum, one pass multilayer mixed metals + oxides 10 Air-to-air multi drum + multi source mixed metals & oxides
10 Untried process, new matls, radical 10 New Co. 1st machine hungry for the work but unproven skills system design, ltd background info
FIGURE 23.2 A simple method of risk analysis.
calculated. The same is not true when it comes to the deposition of a multilayer optical or functional stack to be deposited in a single pass. There may be information about each of the individual materials but not necessarily about the deposition of several of the materials sequentially. If the fastest possible production rate is required it would be usual to try to run multiple processes in the same substrate pass. If the process is done reactively from the metals then the reactive process of each layer may have an effect on the adjacent depositions. If the multilayer stack requires a mixture of metals and oxides the problem increases. The sources need to be matched in deposition speed to allow for the correct thickness of coating to be deposited at the common winding speed. The sources need to be isolated from each other to prevent contamination from each other and the system needs to be symmetric to give the best possible chance for coating uniformity. All of this complexity increases the risk as if any one layer is wrong for any reason the resultant product may be unacceptable. Using the table from above and multiplying each of the risks will give an indication of the scale of the risk. There is no doubt that other factors can also be included such as geographic location, where language, time zones, and availability will affect the risk level. System complexity 3 process risk 3 choice of manufacturer risk 5 total risk As with all risk analysis there are judgments required. What is the true risk of the process? It is common that the person operating the process in the lab believes that there is no risk because they have got it to work. This is not the same as having all the information to make the process universally transferable to any other machine. The choice of manufacturer is also a judgment; seeing machines built does not necessarily mean they have been optimized or are
432
SECTION | 4
reliable. A company that is long established is no proof of current quality. These choices and assessments need to be taken dispassionately and objectively. Part of the use of trying to do a risk analysis is to make everyone think about the whole process of system purchase. A good method to help think through the whole process is to write up a system specification in detail. Any part of the specification that cannot be defined, including the tolerances, is an area of weakness and a potential risk. Some of these will be trivial, others will be more significant but all should be addressed with a view to minimize the risks. It can also highlight risks that cannot be reduced and hence need for these to be monitored throughout to make sure that any problems are found at the earliest opportunity. There are ways that these risks can be minimized. It is usually not practical to take a process that has been developed as a series of single depositions and to build a small-scale single pass process. This is regarded as too expensive and time consuming. What can be done is to use the development system to look at the process sensitivities. Firstly a “design of experiments” matrix can be used to optimize the individual processes and look at the stability of the process. If all the system parameters can be linked to a datalogger then the information can be analyzed further using Chemometrics. Chemometrics is a technique of analyzing data, looking at the natural excursions of parameters during a normal operation of the system. Using mathematical techniques such as principle component analysis (PCA), hierarchical cluster analysis (HCA), known nearest neighbors (KNN) and soft independent modeling of class analogy (SIMCA), it is possible to extract much more information. Typically, this type of analysis would pick out the primary variables and would highlight where insufficient control was available, also the minor variable would be shown along with any interactions. This may not only confirm the expected variables but it may also show up sensitivities that could potentially be damaging to the process that previously had been overlooked. The more information that can be gathered and analyzed and the more closely the final process can be tested and the critical parameters identified and the sensitivity of each determined and as a result the risk can be reduced. The above risk analysis is applied to the process initially. It is worth repeating the risk analysis on the project as a whole and in this way the financial implications can be assessed [6].
23.3 MISTAKE PROOFING OR FOOL PROOFING Mistake proofing developed out of the drive for higher productivity and quality in the 1970s and 1980s in Japan [7,8]. It was found that if something could be assembled wrongly then sooner or later it would be. This assembly error could cause process problems and the final result would be loss of product. In an attempt to eliminate this source of lost product it was aimed to eliminate any assembly ambiguities.
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If we take a new look at a metallizer with the idea of mistake proofing in mind we can find areas where there are weaknesses. If we look at the machine assembly first and then move on to the process, looking at where it is possible for an operator or mechanic to make an error, we can then try to design out that possibility. In production lines, this may mean there is often a sensor included that checks the task has been completed correctly. This may be too expensive as a mistake-proofing tool for metallizers where system costs are very price sensitive. The more simple things that can be done are where a component needs to have a particular orientation the design is done in such a way that it can only be assembled in the correct orientation. Parts such as flanges can be modified easily by adding a dowel and slot eccentric to the clamping bolts one on each of the mating surfaces. In any other position, other than opposite each other, the flange will not mate with the other surface because the dowel will hold it off the surface. This type of arrangement can be used on anything that has to be mounted either within or onto the outside of the vessel. Other parts may require more thought and invention. In metallizers, the most common parts to be removed and reassembled are the shields around the deposition source. It is becoming more common for these to be exchanged and so it is worth checking if these can be misassembled and how this problem might be designed out. Currently, this is not a huge problem in vacuum deposition systems. In the future, it is expected that processes will have to be much cleaner than is currently common practice. This will require much more extensive cleaning between deposition runs and this will require a greater number of easily removed shields and components. Consequentially, there will be an increased chance of assembly errors unless the fittings have been designed with the mistake-proofing philosophy included.
23.4 PROJECT MANAGEMENT Another potential area of weakness can be in the project management. Often the scientist/engineers who developed the initial idea will be expected to take the project through to production. This may not be the most effective use of resources. Unless the people are well trained and good at project management the project will suffer. Many people end up by learning about project management on-the-job with the machine purchase and build being their first project to manage, or where the project is orders of magnitude bigger than anything they have done before. This inexperience becomes one of the risks to be considered in the risk management of the project. Included in the project may be an assessment of the impact of the new process on the company. There may well be an increase in size including recruitment, training, and location of the increase in staff numbers. There will also be an increasing requirement for power, water and other facilities to be prepared for along with all the other smaller details such as increased
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inventory and waste products [9]. All of these can get lost with most of the focus being on the arrival of a new machine. As with all project management it is essential to know what items are on the critical path and to monitor the progress of these items very closely to ensure they do not slip. This is not a trivial task. Many suppliers will delay telling any bad news for as long as possible and it is often the case that the first time that the project manager knows an item has slipped is after the deadline. The fact that an item is on the critical path means that it is unlikely that the time lost can be recovered elsewhere unless some slack time has been built into the program. Suppliers often include hidden slack because they expect there will be some slip on their part of the timeline. If, however, there have been hard negotiations to reduce the design and build times, to get the shortest time to manufacture, then it may be that all their built-in slack time has already been removed. An experienced project manager will closely follow the progress of critical path items and usually has more experience of recognizing when there are difficulties and suppliers are being evasive. Frequently machine suppliers are from across the world to their customers and another evaluation has to be made about how well they will be able to work together. In this electronic age it is possible through e-mail and video conferencing to still have daily project meetings, if required, throughout the design phase to clarify new concepts or confirm and accept modifications. This can reduce the delays in either posting drawings back and forth or in having to move people around the world to have frequent face-to-face meetings. However, this requires a positive attitude on both sides and if there is any culture or personality clash the long distance between supplier and customer can make project management very difficult. Overall it is cheaper to spend the money and to get good professional project management than to have the much higher expense of the machine being late.
23.5 SAFETY Another area that tends to get reviewed later than it ought is safety. It is always harder and more costly to have to modify the machine after it is built than to design in the safety features in from the start. It is worth bringing in all kinds of people such as operators, cleaners, the maintenance staff as well as the scientists to review the design and operation of the process at the time of writing the specification. This ought to be repeated with the final drawings before they are accepted and again a more hands-on review during commissioning and acceptance. Even at that late stage it is still going to be easier to make a modification at the machine builders than it is to wait until it is in production.
23.6 COSTS There are two aspects to this, the cost of the system and the operational cost of the process.
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In the same way that time is always underestimated so too cost is often underestimated. Typically, the cost of the project is 40% more than the basic machine cost and this assumes there is the infrastructure to accept the machine. If a new site has to be prepared then the costs can be several times the cost of the machine. The other aspect of costs is the cost model that is used to determine the cost of the product and the expected profit from manufacturing [10,11]. This will not to be a static model but will get updated as the quality of the information improves. The accuracy of the model will improve as the process is modified and the machine design is modified toward the final optimized process and design at which point the most accurate predictions of process and machine efficiency will be produced.
23.7 MACHINE SPECIFICATION There are different levels of machine specification. Early in the project there may be a single page specification that outlines the basic aim of the process. This is because the basic process is known but not necessarily all the details are known or understood. As more research and development is done and more experience gained of making product it will be possible to provide a more detailed specification. This may be used to help sort out the potential machine suppliers before the final specification is issued from the top two or three machine suppliers. The final specification will typically include details such as the scope of the specification and liability, process description, machine description, mechanical requirements, electrical requirements, control requirements, acceptance trials, packing and shipping, installation, commissioning, maintenance, spares, and training.
23.8 MAINTENANCE AND SPARES This is the less glamorous part of the machine specification but which can be every bit as important to the overall machine operational efficiency. There will need to be discussions around what the maintenance philosophy will be [12]. This can range from no maintenance until the machine stops running through to a comprehensive preventive maintenance schedule. There will need to be thought given to the inventory of spares that will be carried. As can be seen in the trend below it is possible to have a very large inventory cost which will minimize production losses but does not necessarily make economic sense (Figure 23.3). The machine supplier is likely to be able to draw up a series of lists. One of these will have the regularly used items such as “O” rings as used on seals that are regularly broken. A second list may be where there are items included that history would suggest are the most likely parts to fail in
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SECTION | 4 High
Cost/amount of inventory held in store
Low Low
High Risk of production held up for want of spares
FIGURE 23.3 Trade-off of cost of inventory against lost production.
service. A final list would be the most comprehensive one, which might include high-cost spares such as spare pumping units. These spares lists not only need the items listing but also the part number and lead time to deliver in the event of needing a spare. This becomes important when trying to decide on which items to include in any spares inventory. Another part of the equation is the cost per hour of the downtime of the system. There will be some items on long delivery that are cheap and, if not available, will stop the machine running and so can easily be identified as being required. The problem items are the ones that are high cost and have long delivery times and which are machine critical but are seldom a problem. This again is a problem of managing risk. A high-risk strategy is to carry no spares. A low-risk strategy for the machine is to carry a spare for everything but this becomes a high risk for the business because the profitability will be low. There is no simple answer to this problem and much of it depends upon the machine productivity and the product profitability. Another consideration to be made when drawing up a specification is in the choice of items such as gauges and pumps. If you are already in possession of a system it is useful to have the same components on both systems so that the spares inventory can be minimized. This can include having the common roughing pumps of sufficient size to pump both systems with enough spare capacity to be able to take out one pump for maintenance without having to stop production on either system. This would allow for a program of planned maintenance to be done on the pumps with no loss in production. In many systems, the need for large roughing pumps is purely to achieve a fast turnaround time. An alternative method of achieving this is to have a large vacuum tank that is continuously pumped and to use this to assist in the roughing of a system allowing for smaller pumps to be used for the backing of the high vacuum pumps. This type of system also allows for planned maintenance with uninterrupted production.
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REFERENCES [1] Fletcher DA. Guidelines for purchasing, installing and commissioning a vacuum web coater. In: Proc. 36th Ann. Tech. Conf. Society of Vacuum Coaters; 1993. pp. 220 223. [2] Comer AM. Bringing new products to the market place. In: Proc. 12th Vacuum Web Coating Conf.; 1998. pp. 14 23. [3] Cooper RG. Winning at new products. London: Kogan Page; 1988, ISBN 1 85091 769 8. [4] Meyer MH, Lehnerd AP. The power of product platforms. NY: The Free Press; 1997, ISBN 0 684 82580 5. [5] McDonald MHB. Marketing plans how to prepare them: how to use them. 2nd ed. Oxford: Butterworth-Heinemann Ltd; 1989, ISBN 0 7506 0107 8. [6] Raugei P. Evaluation of technology risk in vacuum coating equipment decisions. In: Proc. 10th Internat. Vacuum Web Coating Conf.; 1996. pp. 164 168. [7] Lievens D. Engineering aspects of building a sputtering facility. In: Proc. 7th Internat. Vacuum Web Coating Conf.; 1993. pp. 140 150. [8] Shingo S. Zero quality control: source inspection and the Poka-Yoke system. Translated by Productivity Press. Cambridge Mass, USA; 1986. [9] Poka-Yoke improving quality by preventing defects. Nikkan Kogyo Shimbum Ltd. and Factory Magazine, Eds. Translated by Productivity Press. Cambridge Mass, USA; 1988. [10] Misiano C, et al. Optical coatings on roll-to-roll coaters by reactive deposition. In: Proc. 11th Internat. Vacuum Web Coating Conf.; 1997. pp. 132 137. [11] Jaran JR. The economics of the vacuum roll coating process. In: Proc. 2nd Internat. Vacuum Web Coating Conf.; 1988. pp. 27 34. [12] Boswarva IM, et al. Some experiences in maintaining a vacuum roll coater system for 24 hours-a-day production and high levels of availability. In: Proc. 5th Internat. Vacuum Web Coating Conf.; 1991. pp. 260 290.
Machine Specification and Build Issues — Risk Analysis — Process 23.1 INTRODUCTION If we start by making the assumption that we are working with a worse-case scenario. If we use the scenario that someone has had an idea for a new product and has to take it forward through to production. The process has not been done before and hence the production machine cannot be an offthe-shelf design. Consider that even for a fairly standard metallizer it is probably a 1-year long task, from the point of writing a machine specification then choosing a supplier through to accepting the machine on site [1]. In our case to the time would follow a typical timeline as shown in Figure 23.1 that shows that for most projects the time from idea to production is greater than 3 years and for many cases is often more than 4 years. Some of this time is the natural time taken to do the initial research and development sufficient that a well-written specification can be produced. All too frequently, quite a lot of time is lost around the decision points. Particularly in large companies where many people and decision makers have to be involved to get all the necessary approvals. Rarely are decision points included on the critical path but they ought to be included as they delay any project as much as any late delivery of critical components. It is very common to underestimate the time required to get to the point of production. So many of the items included in the timeline appear on the critical path but are controlled by others who may not be working to the same deadlines or with the same enthusiasm as the owners of the project. The other aspects of developing a new product are to make sure there is a market for the product and also to make sure the market is ready to accept it when it becomes available [2]. It is essential that any market plans are developed in parallel with each and every new product [3 5]. If there is a lack of a market it may need to be developed otherwise there is the risk of the project being stopped.
Vacuum Deposition onto Webs, Films and Foils. DOI: http://dx.doi.org/10.1016/B978-0-323-29644-1.00023-2 © 2015 Elsevier Inc. All rights reserved.
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430
SECTION | 4
Idea
R&D 1 – 2 years
Pilot production
6 Months
Develop machine spec. 6 Months
3 Years + Acceptable new design
Identify preferred supplier
6–12 Months
Machine shipped Re-commissioned Start of production
3–6 months
3 Months
Machine built Commissioned & accepted
FIGURE 23.1 A typical timeline showing the time from idea to production.
23.2 RISK ANALYSIS — PROCESS It is common for processes developed on a small vacuum system to be scaled up without any thought to the possibility of failure of the process. Often a process will have been developed to a point where the envisioned product can be produced. However, the process will not have been optimized. In demonstrating the “proof of principle” of the process any variations in the process and the product outcome will usually have been ignored as being due to the lack of control available on the system. There are two possible sources of the variations. The first is that the variations are due only to the lack of control. The second possibility is that the variations are caused by a variable or a number of variables that not only are not being controlled but are also not even known about. If the process is not well understood then changes that are made during scale-up could be damaging if not catastrophic to the process. Additional work to understand and reduce the risk is much cheaper if carried before the system is built than after it is built. After it is built the costs for not running production are far higher than the cost of additional development prior to the system being designed and built. It is also cheaper to build the system with the correct process than it is to try to modify it once it has been built. A full understanding of the process in all its fine detail will enable a more detailed and more precise specification to be written. This will make the building and acceptance process of the system easier and should minimize any disputes on interpretation of the specification (Figure 23.2). The risks may be small such as for the deposition of a metal from an evaporation source. There is a body of information that is already available about a number of evaporation sources and on systems that have been built up to 4 m web width. Hence most of the information can be pieced together or
Machine Specification and Build Issues Chapter | 23 System complexity 1 Basic metallizing
Process risk
431
Manufacturer risk
1 Established process
1 Established manufacturer + proven experience with specials
3 New process, known materials & established system design
3 Young Co. built some machines inc. one special proven basic skills
2 Metallizing + plasma clean 3 Single layer oxide deposition 4 Single layer oxide + plasma clean 5 Single drum metal + oxide 6 Single drum metal + oxide + plasma 7 Two drum mixed metal + oxide
7 New process, known materials, new 7 Young Co. limited experience, built system design, some background info some machines but still learning
8 Two drum metals + oxides + plasma 9 Multi source + multi drum, one pass multilayer mixed metals + oxides 10 Air-to-air multi drum + multi source mixed metals & oxides
10 Untried process, new matls, radical 10 New Co. 1st machine hungry for the work but unproven skills system design, ltd background info
FIGURE 23.2 A simple method of risk analysis.
calculated. The same is not true when it comes to the deposition of a multilayer optical or functional stack to be deposited in a single pass. There may be information about each of the individual materials but not necessarily about the deposition of several of the materials sequentially. If the fastest possible production rate is required it would be usual to try to run multiple processes in the same substrate pass. If the process is done reactively from the metals then the reactive process of each layer may have an effect on the adjacent depositions. If the multilayer stack requires a mixture of metals and oxides the problem increases. The sources need to be matched in deposition speed to allow for the correct thickness of coating to be deposited at the common winding speed. The sources need to be isolated from each other to prevent contamination from each other and the system needs to be symmetric to give the best possible chance for coating uniformity. All of this complexity increases the risk as if any one layer is wrong for any reason the resultant product may be unacceptable. Using the table from above and multiplying each of the risks will give an indication of the scale of the risk. There is no doubt that other factors can also be included such as geographic location, where language, time zones, and availability will affect the risk level. System complexity 3 process risk 3 choice of manufacturer risk 5 total risk As with all risk analysis there are judgments required. What is the true risk of the process? It is common that the person operating the process in the lab believes that there is no risk because they have got it to work. This is not the same as having all the information to make the process universally transferable to any other machine. The choice of manufacturer is also a judgment; seeing machines built does not necessarily mean they have been optimized or are
432
SECTION | 4
reliable. A company that is long established is no proof of current quality. These choices and assessments need to be taken dispassionately and objectively. Part of the use of trying to do a risk analysis is to make everyone think about the whole process of system purchase. A good method to help think through the whole process is to write up a system specification in detail. Any part of the specification that cannot be defined, including the tolerances, is an area of weakness and a potential risk. Some of these will be trivial, others will be more significant but all should be addressed with a view to minimize the risks. It can also highlight risks that cannot be reduced and hence need for these to be monitored throughout to make sure that any problems are found at the earliest opportunity. There are ways that these risks can be minimized. It is usually not practical to take a process that has been developed as a series of single depositions and to build a small-scale single pass process. This is regarded as too expensive and time consuming. What can be done is to use the development system to look at the process sensitivities. Firstly a “design of experiments” matrix can be used to optimize the individual processes and look at the stability of the process. If all the system parameters can be linked to a datalogger then the information can be analyzed further using Chemometrics. Chemometrics is a technique of analyzing data, looking at the natural excursions of parameters during a normal operation of the system. Using mathematical techniques such as principle component analysis (PCA), hierarchical cluster analysis (HCA), known nearest neighbors (KNN) and soft independent modeling of class analogy (SIMCA), it is possible to extract much more information. Typically, this type of analysis would pick out the primary variables and would highlight where insufficient control was available, also the minor variable would be shown along with any interactions. This may not only confirm the expected variables but it may also show up sensitivities that could potentially be damaging to the process that previously had been overlooked. The more information that can be gathered and analyzed and the more closely the final process can be tested and the critical parameters identified and the sensitivity of each determined and as a result the risk can be reduced. The above risk analysis is applied to the process initially. It is worth repeating the risk analysis on the project as a whole and in this way the financial implications can be assessed [6].
23.3 MISTAKE PROOFING OR FOOL PROOFING Mistake proofing developed out of the drive for higher productivity and quality in the 1970s and 1980s in Japan [7,8]. It was found that if something could be assembled wrongly then sooner or later it would be. This assembly error could cause process problems and the final result would be loss of product. In an attempt to eliminate this source of lost product it was aimed to eliminate any assembly ambiguities.
Machine Specification and Build Issues Chapter | 23
433
If we take a new look at a metallizer with the idea of mistake proofing in mind we can find areas where there are weaknesses. If we look at the machine assembly first and then move on to the process, looking at where it is possible for an operator or mechanic to make an error, we can then try to design out that possibility. In production lines, this may mean there is often a sensor included that checks the task has been completed correctly. This may be too expensive as a mistake-proofing tool for metallizers where system costs are very price sensitive. The more simple things that can be done are where a component needs to have a particular orientation the design is done in such a way that it can only be assembled in the correct orientation. Parts such as flanges can be modified easily by adding a dowel and slot eccentric to the clamping bolts one on each of the mating surfaces. In any other position, other than opposite each other, the flange will not mate with the other surface because the dowel will hold it off the surface. This type of arrangement can be used on anything that has to be mounted either within or onto the outside of the vessel. Other parts may require more thought and invention. In metallizers, the most common parts to be removed and reassembled are the shields around the deposition source. It is becoming more common for these to be exchanged and so it is worth checking if these can be misassembled and how this problem might be designed out. Currently, this is not a huge problem in vacuum deposition systems. In the future, it is expected that processes will have to be much cleaner than is currently common practice. This will require much more extensive cleaning between deposition runs and this will require a greater number of easily removed shields and components. Consequentially, there will be an increased chance of assembly errors unless the fittings have been designed with the mistake-proofing philosophy included.
23.4 PROJECT MANAGEMENT Another potential area of weakness can be in the project management. Often the scientist/engineers who developed the initial idea will be expected to take the project through to production. This may not be the most effective use of resources. Unless the people are well trained and good at project management the project will suffer. Many people end up by learning about project management on-the-job with the machine purchase and build being their first project to manage, or where the project is orders of magnitude bigger than anything they have done before. This inexperience becomes one of the risks to be considered in the risk management of the project. Included in the project may be an assessment of the impact of the new process on the company. There may well be an increase in size including recruitment, training, and location of the increase in staff numbers. There will also be an increasing requirement for power, water and other facilities to be prepared for along with all the other smaller details such as increased
434
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inventory and waste products [9]. All of these can get lost with most of the focus being on the arrival of a new machine. As with all project management it is essential to know what items are on the critical path and to monitor the progress of these items very closely to ensure they do not slip. This is not a trivial task. Many suppliers will delay telling any bad news for as long as possible and it is often the case that the first time that the project manager knows an item has slipped is after the deadline. The fact that an item is on the critical path means that it is unlikely that the time lost can be recovered elsewhere unless some slack time has been built into the program. Suppliers often include hidden slack because they expect there will be some slip on their part of the timeline. If, however, there have been hard negotiations to reduce the design and build times, to get the shortest time to manufacture, then it may be that all their built-in slack time has already been removed. An experienced project manager will closely follow the progress of critical path items and usually has more experience of recognizing when there are difficulties and suppliers are being evasive. Frequently machine suppliers are from across the world to their customers and another evaluation has to be made about how well they will be able to work together. In this electronic age it is possible through e-mail and video conferencing to still have daily project meetings, if required, throughout the design phase to clarify new concepts or confirm and accept modifications. This can reduce the delays in either posting drawings back and forth or in having to move people around the world to have frequent face-to-face meetings. However, this requires a positive attitude on both sides and if there is any culture or personality clash the long distance between supplier and customer can make project management very difficult. Overall it is cheaper to spend the money and to get good professional project management than to have the much higher expense of the machine being late.
23.5 SAFETY Another area that tends to get reviewed later than it ought is safety. It is always harder and more costly to have to modify the machine after it is built than to design in the safety features in from the start. It is worth bringing in all kinds of people such as operators, cleaners, the maintenance staff as well as the scientists to review the design and operation of the process at the time of writing the specification. This ought to be repeated with the final drawings before they are accepted and again a more hands-on review during commissioning and acceptance. Even at that late stage it is still going to be easier to make a modification at the machine builders than it is to wait until it is in production.
23.6 COSTS There are two aspects to this, the cost of the system and the operational cost of the process.
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In the same way that time is always underestimated so too cost is often underestimated. Typically, the cost of the project is 40% more than the basic machine cost and this assumes there is the infrastructure to accept the machine. If a new site has to be prepared then the costs can be several times the cost of the machine. The other aspect of costs is the cost model that is used to determine the cost of the product and the expected profit from manufacturing [10,11]. This will not to be a static model but will get updated as the quality of the information improves. The accuracy of the model will improve as the process is modified and the machine design is modified toward the final optimized process and design at which point the most accurate predictions of process and machine efficiency will be produced.
23.7 MACHINE SPECIFICATION There are different levels of machine specification. Early in the project there may be a single page specification that outlines the basic aim of the process. This is because the basic process is known but not necessarily all the details are known or understood. As more research and development is done and more experience gained of making product it will be possible to provide a more detailed specification. This may be used to help sort out the potential machine suppliers before the final specification is issued from the top two or three machine suppliers. The final specification will typically include details such as the scope of the specification and liability, process description, machine description, mechanical requirements, electrical requirements, control requirements, acceptance trials, packing and shipping, installation, commissioning, maintenance, spares, and training.
23.8 MAINTENANCE AND SPARES This is the less glamorous part of the machine specification but which can be every bit as important to the overall machine operational efficiency. There will need to be discussions around what the maintenance philosophy will be [12]. This can range from no maintenance until the machine stops running through to a comprehensive preventive maintenance schedule. There will need to be thought given to the inventory of spares that will be carried. As can be seen in the trend below it is possible to have a very large inventory cost which will minimize production losses but does not necessarily make economic sense (Figure 23.3). The machine supplier is likely to be able to draw up a series of lists. One of these will have the regularly used items such as “O” rings as used on seals that are regularly broken. A second list may be where there are items included that history would suggest are the most likely parts to fail in
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Cost/amount of inventory held in store
Low Low
High Risk of production held up for want of spares
FIGURE 23.3 Trade-off of cost of inventory against lost production.
service. A final list would be the most comprehensive one, which might include high-cost spares such as spare pumping units. These spares lists not only need the items listing but also the part number and lead time to deliver in the event of needing a spare. This becomes important when trying to decide on which items to include in any spares inventory. Another part of the equation is the cost per hour of the downtime of the system. There will be some items on long delivery that are cheap and, if not available, will stop the machine running and so can easily be identified as being required. The problem items are the ones that are high cost and have long delivery times and which are machine critical but are seldom a problem. This again is a problem of managing risk. A high-risk strategy is to carry no spares. A low-risk strategy for the machine is to carry a spare for everything but this becomes a high risk for the business because the profitability will be low. There is no simple answer to this problem and much of it depends upon the machine productivity and the product profitability. Another consideration to be made when drawing up a specification is in the choice of items such as gauges and pumps. If you are already in possession of a system it is useful to have the same components on both systems so that the spares inventory can be minimized. This can include having the common roughing pumps of sufficient size to pump both systems with enough spare capacity to be able to take out one pump for maintenance without having to stop production on either system. This would allow for a program of planned maintenance to be done on the pumps with no loss in production. In many systems, the need for large roughing pumps is purely to achieve a fast turnaround time. An alternative method of achieving this is to have a large vacuum tank that is continuously pumped and to use this to assist in the roughing of a system allowing for smaller pumps to be used for the backing of the high vacuum pumps. This type of system also allows for planned maintenance with uninterrupted production.
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REFERENCES [1] Fletcher DA. Guidelines for purchasing, installing and commissioning a vacuum web coater. In: Proc. 36th Ann. Tech. Conf. Society of Vacuum Coaters; 1993. pp. 220 223. [2] Comer AM. Bringing new products to the market place. In: Proc. 12th Vacuum Web Coating Conf.; 1998. pp. 14 23. [3] Cooper RG. Winning at new products. London: Kogan Page; 1988, ISBN 1 85091 769 8. [4] Meyer MH, Lehnerd AP. The power of product platforms. NY: The Free Press; 1997, ISBN 0 684 82580 5. [5] McDonald MHB. Marketing plans how to prepare them: how to use them. 2nd ed. Oxford: Butterworth-Heinemann Ltd; 1989, ISBN 0 7506 0107 8. [6] Raugei P. Evaluation of technology risk in vacuum coating equipment decisions. In: Proc. 10th Internat. Vacuum Web Coating Conf.; 1996. pp. 164 168. [7] Lievens D. Engineering aspects of building a sputtering facility. In: Proc. 7th Internat. Vacuum Web Coating Conf.; 1993. pp. 140 150. [8] Shingo S. Zero quality control: source inspection and the Poka-Yoke system. Translated by Productivity Press. Cambridge Mass, USA; 1986. [9] Poka-Yoke improving quality by preventing defects. Nikkan Kogyo Shimbum Ltd. and Factory Magazine, Eds. Translated by Productivity Press. Cambridge Mass, USA; 1988. [10] Misiano C, et al. Optical coatings on roll-to-roll coaters by reactive deposition. In: Proc. 11th Internat. Vacuum Web Coating Conf.; 1997. pp. 132 137. [11] Jaran JR. The economics of the vacuum roll coating process. In: Proc. 2nd Internat. Vacuum Web Coating Conf.; 1988. pp. 27 34. [12] Boswarva IM, et al. Some experiences in maintaining a vacuum roll coater system for 24 hours-a-day production and high levels of availability. In: Proc. 5th Internat. Vacuum Web Coating Conf.; 1991. pp. 260 290.