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Risk response strategy can focus on correction after a risk becomes a reality or prevention to ensure a risk does not become a reality. The FMEA methodology prioritizes risks to determine which risks should be prevented.

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Quick reference

Correction and Prevention

Risk response strategy can focus on correction after a risk becomes a reality or prevention to ensure a risk does not become a reality. The FMEA methodology prioritizes risks to determine which risks should be prevented.

When to use

Correction strategies are based upon fixing an identified problem – normally one that is current in the products or processes.  Prevention strategies are based upon reducing the number of things that could go wrong, or reducing the impact those would have if they occurred.  FMEA is a prevention technique that is normally applied during the design of products or processes.

Instructions

There is a purpose for both correction and prevention action in any organization’s quality strategy.  The corrective action often gets the priority because there is an irate customer, a production line shutdown, or a high amount of scrap and rework costs that must be immediately addressed.  Those do need to be addressed, but a preventive approach would reduce the amount of corrective action that is required. 

Corrective Action

Corrective action approaches fix known problems.  There is something that must be corrected.  Often the corrective action must first contain the problem to be sure it does not spread and to determine the magnitude of the impact.  Then the corrective action must determine the root cause or causes of the problem.  Depending upon the nature of the problem, the defective items may be fixed through rework or repair.  A company that relies heavily on corrective action instead of preventive action will likely need a large parts and service department, along with high warranty costs or service level agreements.  To achieve high levels of customer satisfaction, the company must often over-design the product to create a “heavy duty” version that can absorb small problems.  In addition, a problem solving or corrective action process must be in place.

Preventive Action

Preventive action approach attempts to avoid problems by designing in safeguards and designing out vulnerabilities.  Through product design you can remove susceptibility or add the ability to automatically respond and counteract the effects of a failure or defect.  Through process control you can limit the enabling conditions that allow a defect to occur.   Or you can again over-design the product so that it is less likely to ever experience the problem to begin with.  A company that relies on prevention must put in the upfront effort during design to anticipate scenarios that would create problems and build in a response.  This normally takes cross-functional design work using tools such as the FMEA.

Law of Defects

There is a set of principles talked about in the quality community known as the law of defects.  While I have never seen a research study that demonstrates the accuracy of these, the anecdotal experience of myself and countless others has given these principles credence.

  • 75% of defects are caused by design decisions
  • If a defect is found in normal operations, it is not the first time it occurred
  • Quarantine efforts to isolate problems are not 100% effective
  • “Inspecting in” quality is difficult, expensive and only partially effective

While FMEA is a preventive action technique, Lean Six Sigma is an excellent methodology for corrective action.  There is a known problem to be addressed.  When the methodology is followed and applied correctly, it will normally lead to a permanent fix to the problem.  An FMEA is helpful with Lean Six Sigma because the FMEA analysis can provide insight into likely root causes.  An FMEA risk mitigation strategy that did not work will normally result in quality failures that lead to the need for further corrective action.  Since the Improve and Control phases seek to put in place and maintain a permanent resolution to the Lean Six Sigma project’s problem, an FMEA can assist Lean Six Sigma in the analysis of the solution to ensure it does not create new unintended consequences.

Hints & tips

  • A company should plan on both preventive action and corrective action.  The more preventive the less corrective, but you can’t totally do away with corrective action.  There will still be the totally unexpected event that needs corrective action.
  • The old adage, “an ounce of prevention is worth a pound of cure” applies to quality improvement.  Preventive action is normally less expensive than corrective action.
  • Corrective action often leads to “heroics” and commendation for fixing a problem.  No one gets recognition for preventing a problem.  Therefore, you should affirm efforts like FMEA to encourage their adoption.
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  • 00:04 Hi, I'm Ray Sheen.
  • 00:06 As we continue to lay the ground work for performing the FMEA,
  • 00:09 let's review the concepts of prevention and correction.
  • 00:14 Let's start by considering the relationship between the FMEA and
  • 00:18 Lean Six Sigma.
  • 00:19 FMEA is a problem prevention methodology.
  • 00:22 It is normally used in the design process to identify potential problems and
  • 00:26 make a change to avoid that type of failure.
  • 00:29 Lean Six Sigma is a problem solving process, so it is corrective action,
  • 00:34 the problem exists.
  • 00:35 With Lean Six Sigma, you find out why it exists, and
  • 00:38 decide what can be done to correct the situation and avoid future problems.
  • 00:42 Now when an FMEA was done during design, it will help the Lean Six Sigma team.
  • 00:47 The FMEA will identify potential causes.
  • 00:50 And the team knows to check the FMEA mitigation to see if it was effective.
  • 00:54 So it also helps the Lean Six Sigma team to know what
  • 00:56 data to collect in the measure phase.
  • 00:59 And when a Lean Six Sigma project finds that their improvement requires
  • 01:03 a redesign of the product or process,
  • 01:05 creating an FMEA for that redesign will improve overall design performance.
  • 01:10 The FMEA will identify what risks to mitigate and
  • 01:13 it helps to reduce the likelihood that the Lean Six Sigma change will introduce
  • 01:17 any unintended consequences.
  • 01:20 To give this idea of prevention and
  • 01:21 control a bit more context, let's look at the Law of Defects.
  • 01:25 There are several parts to the Law of Defects.
  • 01:28 First, that over 75% of the defects are because of design decisions.
  • 01:33 Some are obvious, like choosing materials that are not appropriate for the use.
  • 01:38 But even when it's a mistake in manufacturing,
  • 01:40 often those are because of poor design practices.
  • 01:43 Design complexity or fragility leads to mistakes by the shop floor operator.
  • 01:48 Another part of the Law of Defects is that if a defect is found,
  • 01:51 it's probably not the first time that it has occurred.
  • 01:54 There are likely more defects like it either in the pipeline or
  • 01:57 already in the hands of customers.
  • 01:59 And yet another aspect of the Law of Defects is that relying on quarantining
  • 02:03 defects is never 100% effective.
  • 02:06 You may think that your process will always catch and
  • 02:08 quarantine the defects or failed items, but it won't.
  • 02:12 Sometimes one of those will slip through and get to the customer.
  • 02:16 And the final part of the Law of Defects is that if your process generates a lot of
  • 02:20 defects, but you decide on a strategy of inspecting in quality.
  • 02:25 Which means that you will put a lot of inspectors and
  • 02:27 test steps in the process to find problems.
  • 02:30 Well, that just adds a lot of work, a lot of expense and it won't be 100% effective.
  • 02:36 So the bottom line is that due to the Law of Defects,
  • 02:39 you wanna go with a proactive preventive approach to failures and
  • 02:42 problems, not a corrective action approach.
  • 02:45 Prevention will lead to better quality and reliability.
  • 02:49 This is the core concept behind the FMEA.
  • 02:51 So I wanna take just a few minutes with it.
  • 02:54 One approach to risk response is corrective action.
  • 02:57 This type of response is pretty easy to understand.
  • 03:00 When a problem, a failure, or a risk occurs, well, you fix it.
  • 03:04 You find out what's gone wrong and you make it right.
  • 03:06 Now in the business world, that often includes a couple of things.
  • 03:10 One is that you contain the problem.
  • 03:11 You check the products or process output to find out what has been affected.
  • 03:16 And if necessary you do a recall to bring back the defective parts or
  • 03:19 systems that have made it out to the customers.
  • 03:22 You may need to shut down a line until you can get to the root cause of the problem.
  • 03:28 Once you find the root cause, then you fix it.
  • 03:31 At the same time, you may be able to repair or
  • 03:33 rework the items that had the failure or a defect and make them acceptable again.
  • 03:39 Now, on one hand, you may think this is an inexpensive way to address quality.
  • 03:43 You don't waste any resources on doing things that aren't problems.
  • 03:47 Instead, you just focus on the problems.
  • 03:50 But there are a number of business cost and
  • 03:51 considerations that must be addressed when you use this approach.
  • 03:54 One is that due to the uncertainty of when the next problem will occur,
  • 03:58 you need to create spares for replacement and
  • 04:00 build in excess capacity to make up for lost production.
  • 04:04 And of course, there are the warranty and service costs of fixing the problem and
  • 04:08 the cost of running corrective action systems.
  • 04:10 Which is often dealing with crises, so as paying overtimes and premiums.
  • 04:15 Not to mention that many times, we just start off by over designing the product or
  • 04:19 process and let the over design try to cover for the small problems.
  • 04:24 A different approach is to go the preventive route.
  • 04:27 Rather than fixing the problem after they occur,
  • 04:30 you take the preventive action to make sure that they will not occur.
  • 04:34 That means you have to remove the susceptibility to that risk, or
  • 04:37 remove the source that initiates the risk.
  • 04:39 Susceptibility may be removed through design decisions.
  • 04:43 Also, the enabling conditions that cause the occurence can be designed or
  • 04:47 controlled for.
  • 04:48 Finally, some risk can be eliminated by product or
  • 04:51 process self-control and self-correction.
  • 04:54 This would include redundant systems or automatic response to risk conditions.
  • 04:58 Of course, one option for prevention is similar to what we can do for control.
  • 05:03 Over design a product or process, so that the design margin is greater than
  • 05:07 the small problems and they don't impact the product or process performance.
  • 05:11 These types of preventative actions normally take a coordinated
  • 05:15 cross-functional team, and that is where the FMEA is a great help.
  • 05:19 It is a technique that brings the functions together and addresses these
  • 05:23 issues like susceptibility, likelihood of occurence, and the capability to respond
  • 05:28 or to react to a potential issue, without creating other unintended consequences.
  • 05:33 Prevention is more predictable and often a lower cost approach than correction.
  • 05:39 FMEA is one of the best tools availbale for coordinating and
  • 05:43 prioritizing preventive actions.

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