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Difference between Quality Management and Lean Manufacturing |
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If you have any questions about our Quality Matrix, or wish to make any comments, please feel free to send a message to us at quality@artige.com. |
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| Overview |
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This analysis is just one of many comparisons that are offered as part of the Artige Quality Matrix, which can be seen here in its original form. The definitions that are used in these comparisons are the ones that we at the Artige Company use internally and with our clients, derived from the research that we perform as a matter of due course. These definitions are derived from natural laws of physics and statistics, in order to screen our work from the effects of the business press. The original article where these terms are discussed appears here. In other words, we like to think that this work will withstand the scourges of time and not be categorized as "management du jour". |
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| Quality Management |
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Definition |
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We like to use this category as a catch-all for the quality methods that are not founded by obvious cause and effect methods. That is, those methods that are driven more by personalities than particulars. We also like to lump in the traditional quality control methods, as it can be shown that the quality management practices are a result of the original "measure and reject" philosophy of quality control. |
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Quality management is based upon heuristic and ad hoc methods, based on previous experience. Note that there is nothing wrong with that, and it can be deployed very successfully. It is just that certain individuals like a predictable and deterministic methodology, and an ad hoc method does not fit such a constraint. The quality management methodology has its roots in traditional quality control in production, where conformance to requirements is the major point of interest. |
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We use a waterfall method to explain where quality management comes from, which is based upon quality control and quality assurance. This is described by the three definitions below: |
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| QC |
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The main task that the quality control methodology sets out to accomplish is to insure that only good items were acceptable for further production, and bad parts were rejected. To have the concept of good and bad parts means that standards of some type must be in place, so comparisons can be made. The fact that good and bad parts could exist was not the main concern (and is still not) of quality control. Any activity that is related to measuring product parameters against criteria and passing judgment on whether the product can be used or sold based on meeting the criteria is considered a quality control task. This covers final goods, intermediate work-in-progress or services being delivered. |
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| QA |
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Obviously, a regime of rejection will only get a business so far, and could result in an unprofitable situation if most parts are rejected. So the obvious step to take is to prevent the rejections, which is typically done by assessing the processes that are causing the rejects in the first place. This method is called quality assurance. This practice considers all aspects of production, insuring that raw materials are fit for consumption, equipment is operating as desired, as well as maintained properly, and that all the constraints from customers have been collected, documented and integrated back into the constraints used for production. So, activities related to preventing rejected parts or services would be considered part of a quality assurance practice. |
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| QM |
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The next obvious step for the enterprise that is able to prevent rejections is to tighten the constraints, which should result in better financial performance, owing to the fact that fewer resources are being used, with a resulting drop in costs. This is considered quality improvement, and the practice that handles this would be considered quality management. Whereas the two previous practices of quality control and quality assurance have a cause and effect relationship, the prediction and improvement of defects enters an area that is not amenable to a cause and affect analysis. No one set of rules exists that one can deploy to improve a process. |
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This category of process design is extremely interesting, in that it is the reason why there are so many other methodologies to handle the process design and quality needs of an enterprise. We cannot emphasize more clearly, "no one set of rules exists that one can deploy to improve a process". All of the methodologies listed in this report are an attempt to overcome this shortcoming. Since there is no cause and effect relationship that can point one in the one and only direction to improve their processes, all of these other processes are acceptable, and can never be proven invalid or unsound in every case. All that one can do is determine which of these processes fits one's way of operating and still be able to meet the criteria set by the customer. |
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Since this is the methodology that brings up the point that there is no cause-and-effect method to improve processes, we like to use quality management as the moniker to point to the ad hoc and people-oriented methods. That is because as the quality improvement concept advanced, this method would be the first that recognized human intervention was needed to improve process outcome. Most of these process improvement ideas came about in an ad hoc manner, just from trial-and-error and previous experience. Since previous experience is such a great factor in promoting prevention and improvement, the practitioners of quality management will always be focused upon people-oriented methods that pull out best practices from the experienced workers. |
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Quality management is also where that concept of announcing the company financials to production workers came about in a big way. The idea here is that education and knowledge of the workforce is important, in order for them to understand where their paycheck comes from, and that they have an input in the processes that allow them to maintain their cash flow. This focus on financial measures then proves to the organization membership that ignoring quality holds a price for non-conformance. |
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Note that the workforce education component is a tricky area. There are two facets to this factor. On one hand one could just announce the data and expect that the workforce will consume the data to everyone's advantage. This also allows certain executives to claim they are open and honest with their workforce. There is another step that is probably necessary. One will need to explain, and even tutor, what the meaning is behind the raw data. In other words, how will the workforce gain knowledge from the financial data? The first option to just announce the data opens the door for misunderstanding and mistrust, which is why the second option is preferred. |
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All of the above tasks would be categorized as incremental in terms of implementing change. |
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| Lean Manufacturing |
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Definition |
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The main concern of lean manufacturing design is to eliminate waste. The main desire is to reduce the production cycle, which eliminating waste should accomplish. Lean also has a focus on retaining tasks that add value, and eliminating non-value adding tasks. Other concepts having to do with time and waste are important to lean manufacturing. Lean manufacturing is normally driven by customer demand. This brings up the point about what the driver of a business process should be. The two concepts are push and pull. Most concepts of lean involve a pull scenario. This is in comparison to the "traditional", "out-of-date", or "old-fashioned" push scenario. In the good old days companies manufactured to stock, filling warehouses with product that marketing was responsible for emptying out. The push method involves carrying costs and results in various types of waste, especially as the product lifetime came to an end. |
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| Pull-driven |
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In a pure pull scenario, the customer demands the product, and the manufacturer creates or delivers the desired product at the moment the demand signal is received. Based on today's technology, the marketing department closely monitors the customer' needs, or the customers themselves can directly make their own demands, so the firm is able to react very quickly to market conditions. Note the word "react". It is a term that lean and TQM aficionados would like to eliminate from business vocabulary, as it foreshadows the waste to come. To accommodate pulling, minimal amounts of work-in-progress and inventory will be desired in the process design, otherwise there must be additional steps that are adding delay, which will result in waste being generated. |
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| Takt time |
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When considering Lean manufacturing, one also has to take into account the concept of flow, which is driven by a production beat, that being called "takt time". Flow reinforces the notion that lean manufacturing requires constancy and cannot tolerate interruptions, otherwise additional amounts of waste will be generated. The term "takt time" describes the average amount of time it takes to manufacture a product or deliver a service, expressed in terms of a cycle. In other words, one might be able to manufacture one unit of a certain part in 120 seconds. However, if one needed to manufacture 2000 units of the part, will it still take 120 seconds per part? Takt time takes into account the flow of production, and requires that a process to run at a consistent rate, to the constant beat of a production clock. The concept of takt time recognizes that many business processes need to run at a consistent rate in order to maintain the highest quality and still deliver product at a particular volume. With takt time, one can visibly see when a problem might be brewing. If the production rate becomes erratic and inconsistent, or changes from a given norm, then some aspect of the process has failed. However, a period of erratic production may occur when the takt time period was purposefully altered. |
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| Lean Management / Lean Thinking |
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One will see the terms of lean manufacturing, lean management and lean thinking used interchangeably. From what we have found, there is no difference between these terms. They are all driven by the same methodology of cutting waste. The vast majority of lean manufacturing implementations have been applied to manufacturing, but there is no reason why it could not also be applied to service processes. Lean manufacturing would be considered incremental in the rate of change being applied. |
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This last concept of purposefully altering takt time helps explain an inconsistency that one might think exists at first glance between pull-driven manufacturing and takt time. If a lean manufacturing process was based upon a consistent, never-varying takt time, how can it deal with changes in demand? The answer lies in the fact that a takt time system does not react to every demand whim on a first order basis. Rather, a second order function is used, that watches the rate of change in demand. This rate change will manifest itself in a change to the takt time period of the production line. The takt time change may result in some waste (time, resources, cost, depending on the situation). In the end the total cost of operating the production line with a takt time is supposed to compensate for the waste that may occur with individual takt time period changes. |
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| The Difference |
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The Differences and / or Similarities |
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At first glance, one would think that Quality Management and the Lean principles do not have much in common, other than the fact that they both deal with the topic of quality. They are both methodologies that can result in some sort of improvement in the quality of the products or services offered. One method is in actuality a quality regime, while the other is based upon redesigning the operating processes. So these two methodologies take different approaches, resulting in different outcomes. |
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Lean Manufacturing offers a direct approach to improving quality in an existing system, through process design changes that are aimed at reducing waste. It also imposes the constraint that the business processes should be driven by customer demand, and provides the hint that a process runs with better quality when it can be run at a consistent rate, according to Takt Time. In summary, the lean principle offers the benefit of higher quality if one is willing to perform some process redesign and then operate them with the customer and clock in mind. |
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Alternatively, Quality Management takes an indirect approach to improving the quality of an organization. It is based upon the premise that deploying Quality Control, and then regulating the Quality Control regime with a Quality Assurance regime, plus improving the Quality Assurance principles with a Quality Management process will instill an environment of quality in the enterprise. The latter relies solely on the experience and knowledge of the enterprise workers to drive the process changes and improvements. The more knowledgeable the workers, the better the chance to improve quality. |
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So on one hand with Lean Manufacturing we have a methodology that provides specific guidance on how to improve processes that should result in improvement in quality. These are direct steps that one can take, but may not be simple or trivial to implement. One must realize that any time process redesign is suggested, effort must be exerted, and probably capital funds will need to be spent. On the other hand, Quality Management uses direct methods to maintain quality and indirect methods to possibly improve the quality of business processes. Both methodologies should result in changes to the underlying operating processes. So the main difference between these methodologies is that Quality Management is open ended with the improvements that could be implemented, while the lean principles declare that elimination of waste is the one way to accomplish improvement in quality. |
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Note that in the Quality Management methodology the outcome will be an indirect result of deploying the management processes. With its ad hoc basis, there is nothing to mandate what level of quality is expected or desired. Note too that a quality management regime could adopt lean principles as part of the improvement process. If this occurs, it will do so as a result of trial and error, not as part of a planned course of action that dictates lean principles must be part of the business process design. |
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