The Role of Inspection within Quality
Akinori Hyodo, former Factory Manager, Toyota HiAce Factory | #AskSensei Event 23 Summary
Many companies include quality inspection as part of their quality control process. However, from a lean perspective, inspections add no value to the products being produced. Akinori Hyodo discusses the importance of quality assurance and delves deeper into the role of inspection within quality. He also explains why introducing inspection in your process should not be regarded as a countermeasure to your quality issues.
The Role of Quality Inspection
Today, we will be covering the role of inspection within quality and how we can assure the quality of what we are producing. I believe that quality is something that all of you joining us today grapple with from time to time within your own companies.
Regardless of the type of business we are running, in order to gain and maintain the trust of our customers, one of the most important things we must assure is quality of our products. And, one way of doing this is through what we refer to as inspection. However, when looking at the idea of inspection from the perspective of lean and how we talk about waste in the world of lean, inspection does not actually add any value.
So, from this perspective, we want to be providing our products and services to our customers without the need for inspection. This is an ideal situation. However, the reason why we have inspection is because of a lack of capability at present in achieving 100 percent quality. When this is the case, what do we need to do to help us move away from having inspection as part of our process?
The thinking in Toyota regarding quality is that each step in the process along the value stream should be guaranteeing the quality that is coming out of that individual process. This means that they are not passing on any defects to the next process. In order to assist with this situation, within the standard work created for each role within our process, there is always a reference or a step incorporated to check and assure quality.
Having said that, what we humans do is not always 100 percent perfect. Since it is people performing the work that is described in the standard work documents, mistakes can be made and some elements of the work may not be performed correctly to achieve the level of quality we have promised – perhaps one in every million times, for example. We need to be aware that human errors can occur.
However, if you are the customer receiving the defective product, even if it was just one defect in a million, the defect ratio from your perspective as a customer is 100 percent. So, as I mentioned previously, even if you achieve the 1 ppm (one part per million) level of defects, that level is still unacceptable as quality is either zero or 100 percent. There is no grey area between those two numbers when it comes to quality.
I’d like to encourage you not to be satisfied with a one ppm level of defects. We must not accept that. We should be aiming for zero defects instead. And, there are several methods used to achieve that. One method of avoiding human error is poka-yoke which we covered off in one of our earlier #AskSensei webinars. Another method is, as I mentioned earlier, to build a quality element into the standard work and make quality checking an integral part of the standard work we create. There is also an approach from the equipment side of things. We have a principle of stopping what we are doing when we detect a problem in order to address the problem immediately. And, this concept is also incorporated into our equipment and machines so that we are not producing a defect and not passing the defect on to our next process when a quality issue is detected.
In doing all that, in theory, we should have no defects being produced. But, of course, we may still experience defects in what we are doing. Even in Toyota, we have defects.
So, what do we do regarding those defects? For each individual case that we experience, we get into the detail behind what occurred with the defect and go through the cycle of improvement for each individual occurrence and do this over and over again. In doing that, we are reducing the number of defects that we are experiencing over time. Particularly what we want to avoid when we take countermeasures against the defects we experience is having the same issue reoccur. Avoiding the recurrence of the same issue is an important concept for us. We take action to ensure the same issue won’t be experienced a second time.
So, the actual role of quality inspection is to confirm that we are getting the desired outcome from the countermeasures we put in place.
When you look at the world of inspection more closely, there are different types of inspections that we do with each one of them having its own objective behind why we are doing it.
Firstly, there is an inspection to determine good quality products from defects. This type of inspection is done with the companies that do not have enough capability to produce good products in a consistent manner. In this case, since you don’t know when defective products are produced, you will be conducting an inspection on every single item you have produced in order to separate good products from defects.
But, as your company increases its capability through various countermeasures, then you can move away from the need to have this type of total inspection and move towards an inspection to reassure that every product you are producing is of good quality. This is the best type of inspection you would be conducting.
At this point, I would also like to draw your attention to what people often get confused with regarding inspections. What I often hear is that people put inspections as a countermeasure against quality issues. But, assigning someone to perform inspection is not a countermeasure as such. Please don’t make this mistake. As I said earlier, inspections are conducted in order to determine whether a product quality is good or poor. So, when you experience a defect, make sure to get down to the root cause of what’s behind that defect and take action accordingly to prevent the same issue from happening again. This is what implementing a countermeasure is all about. So, when you assign a person for inspection, use the person to confirm the effect of the countermeasure. If you don’t take this approach and merely put inspectors at the end of the process as a “countermeasure” to separate good from poor, you head down a dangerous path of dealing with human errors in your inspection process as well. And, you could end up with putting in another person for inspection to inspect the work which already has been inspected. In this way, you may end up with double, triple or more inspections. Then, where does this end?
As I mentioned earlier, there is no value add regarding the step of conducting inspections. So, if you increase the amount of inspection work you are doing, you are increasing the amount of waste that you are experiencing.
So, at the risk of repeating myself, I must reiterate the importance of following the principle of stop what you are doing immediately when you experience a defect. Once this first action is taken, you must ensure that you get down to the root cause of what was behind the occurrence of that defect. However, many seem to fail to do so and deal with the quality issue at a surface and phenomenon level. But, make sure to address the problem at a root cause level to prevent the same problem from occurring again. If you can do so, my experience tells me that the recurrence of the same issue will be prevented by addressing the issue at its root cause level in 97 or 98 percent of cases, if not 100 percent.
In the world of quality improvement, there are various things you can do as I mentioned earlier. But, I regard what I have just said as the most important thing you can do – when you experience a defect,be sure to get down to the root cause of the issue and get on top of this on a daily basis and repeat this over and over again.
Whether you satisfy your customers or not largely depends on whether you can gain their trust through quality. So, do your best to incorporate all these points on a daily basis in order to improve quality to gain trust from your customers.
If we stop production due to a quality defect and the defect can’t be solved and corrected within a short period, do you recommend sending the operators home until the issue is resolved. Although quality is a priority, should the cost of paying operators for unproductive time also be a consideration?
First of all, the response to this does depend on the size of the issue. Certainly, when we experience a quality issue, we stop the line. But, I am sure any business would wish to keep the line stoppage time as short as possible. So, depending on the size and the level of the issue, there are two stages in terms of our response.
The first stage of our response would be implementing a short-term measure so that we will be able to get the production up and running again as quickly as possible. The following stage is to put a solid countermeasure against the problem. The short-term measure to be implemented is different from a countermeasure which addresses the issue to ensure that the problem doesn’t happen again. The short-term measure helps to acknowledge and address the issue in order to get the production moving quickly again. If we were to adopt a countermeasure against every single issue that we experience, that would cause us a huge loss of time on the line. But, we must make sure the first stage of response is followed by the second stage so that the root cause of the problem is addressed and appropriate countermeasures are put in place.
So, with regard to what we do in terms of the operators and their salaries in the case of a line stoppage, I would like you to consider the difference between a momentary loss and a total loss caused by the issue. For example, if your company has a policy of not stopping the line when you find an issue, what you are doing is letting the issue escape and addressing it later. What you tend to experience in this case is that as you would end up spending more time and resources somewhere down the track as you would need to perform rework on the defects and would probably need more people to be working off the line to complete the rework. So, there will be a considerable loss and expense in dealing with the issue later. But, in the case of stopping the line when you experience a defect in order to deal with the issue, the momentary loss you would experience would be much longer. However, if you crunch the numbers to compare the two types of scenarios, you will find that the second approach wins over in terms of the total loss caused by the issue.
Another point I wish to make is that depending on the type and the size of the problem the company is experiencing, there may be a need for different parts of the business to be involved as well. For example, in the case of a claim coming from a customer, that information will go straight to the top of Toyota and then that will come down through the organization involving and engaging many different parts of the business to overcome the issue.
The fundamental thinking around quality is that we should always put quality before cost. But, since we are a company and we are running a business, we need to keep our eye on cost as well. So, we engage the power of many different parts of the organization to work together to eliminate as much waste and loss as possible.
The reason why the different parts of the business need to be engaged is because the production side alone cannot deal with everything. With regard to quality issues, it may require the involvement of the Quality Assurance Department. In some cases, it may require the involvement of the top person in the company to provide directions as to what should be done.
With this in mind, in Toyota, roles and responsibilities of each different department and each level of the organization are clearly determined to deal with quality issues. So, when an issue does occur, people know who needs to be involved and what needs to be done. If this is not the case within your organization, I encourage you to reflect on this point once again and determine the roles and responsibilities of those at each level of the organization.
What is the Toyota HiAce plant doing currently with respect to standard operating procedures and task-specific training for employees? In particular, how is work content handled that is directly related to high RPN (Risk Priority Number) score process steps in their PFMEAs (Process Failure Modes and Effects Analysis)?
Firstly, I’ll address how we train our employees when they start to work at our factory. Initially, we raise the basic skills of our new operators up to a 70 to 80 percent level of the ability required to be able to perform the standard work. This is done offline before we introduce them to the main line. Once we put them onto the main line, we will have somebody with more experience work together with them throughout the shift for a period in order to help them get up to the 100 percent level. The support person evaluates the new operator every day until he/she knows for certain that the new operator is able to perform the standard work independently to the level required.
Once the support person training the new operator steps away, the team leader and the supervisor for the area where the new operator is working will observe the new operator frequently to check on their standard work to ensure they are following what they have been trained to do.
This is done on a very regular basis and if they find someone who is not performing the standard work to the level required, they will teach and train the person again so that he/she can perform the standard work properly.
With regard to the second half of the question, in the standard work that we create, document and train from, where there is a step that does have a higher risk associated with quality, we put a rank alongside that step within the standard work such as rank A, rank B, etc., to indicate that the particular step is more prone to create defects than other steps. In doing so, we can ensure important emphasis is placed on those high-risk steps during training as well as when we are confirming and checking the standard work being performed.
An important role of the team leader as well as the supervisor who is looking after multiple teams of the area is to find problems and address those problems. This is what they need to be doing on a daily basis as a key role in those positions. So, it is extremely important that they look closely at the work performed by their team members. However, in my opinion, there are not many companies in the world that are currently doing this well enough.
I am not going to claim that Toyota is a perfect company. We experience issues on a daily basis ourselves. Even with the standard work we create, we can find problems and points to be improved. So, it is really important for our leaders within Toyota to be looking carefully at the work that is being performed, particularly around how the operators are following the standard work as well as the standard work itself. They do this on a daily basis to find where problems are and address them when problems are detected.
Are there steps in Toyota’s standard work at the process level to inspect the quality of incoming work as well as the quality of completed work before passing onto the next process?
Firstly, in principle, when a product reaches the downstream process from an upstream process, there is no inspection of these incoming items. However, if the operators working within the downstream process believe something is not quite right or there is a problem with the product they received from the previous process, they will stop what they are doing and call for assistance from someone off the line within the team to have a look at what is wrong with the product. But, in general across the Toyota Group there is no inspection of the quality of products received from the upstream process.
However, with regard to your own process and passing your products onto the next process, yes, there is a quality inspection step incorporated in the standard work to make sure that what is produced within your own process is checked before being passed onto the next process. As I said earlier, the quality of your products must be guaranteed within your own process.
An easier way to think about this is from the viewpoint of a supplier and customer relationship rather than a relationship within the same factory. In the Toyota supply chain, suppliers are the ones doing the quality inspections of their products before they leave their premises to ensure what they are delivering to their customers are of 100 percent quality. So, no inspection of incoming goods are performed on the customer’s side. This is the general rule within the Toyota group.
This links in with the concept of ensuring the quality out of your own process and not passing defects downstream. And, this is exactly what is happening at the level of the supplier-customer relationship within the Toyota group as well. So, this concept is also reflected in the standard work being created for each process within the Toyota group.
How do senior leaders in an organization, who are separated from the work, understand the benefit of the granularity of standard work?
This is a tough one, isn’t it? You perhaps don’t need leaders thinking like that within your organization, do you? As I always say, the work and directions within an organization come from the top of an organization and go though to the bottom. They don’t come from the bottom and go up.
It is hard to get traction when the understanding and the adoption of lean is only happening at the lower end of an organization. It really needs to come down from the top of the organization. That’s why I always say it’s a top-down approach and the thinking and approach of those at the top of the organization needs to change first. Otherwise, it will be extremely difficult to implement lean throughout the rest of the organization. You need to work on the top of the organization and change their outlook, awareness and view of how they work within their organization and filter that through from the top of the organization to the rest.
But, as for standard work, good understanding of the importance and the detail of the standard work isn’t actually going to be developed by those higher up in the organization who are working in a separate location within the organization. So, this should be dealt with by those at the supervisor and manager level of people who are working on the shop floor.
What I see as a problem here is that those higher up in the organization are separated from the shop floor and not spending enough time closely looking at what is really happening on the shop floor on a regular basis. So, if you are at a lower end of your organization and struggling with those above you, you should encourage those higher up in the organization to spend more time observing the workplace and developing a more intimate understanding of what is really happening and what kind of problems there are in the workplace.
An approach you could take from lower parts of the organization is to encourage those higher up in the organization to come down to see your workplace physically. For example, you could hold an event and invite those at the top of your organization to show them particular improvement points and themes that you and your team members have been working on, be it on the theme of standard work or whatever you choose. You can show them what is really happening on your work area. Through such efforts, you can start to engage them and make them come down to your work area more often. This could be a strategy that may work to encourage those higher in your organization to regularly pay attention to the shop floor.
#AskSensei is a regularly-scheduled webinar held together with Shinka Management Senior Lean Consultant Akinori Hyodo, who formerly enjoyed a career with Toyota rising from operator and team leader at Toyota, right up to factory manager and director of Toyota’s HiAce Factory. Each event we cover a different topic related to lean, with participants invited to put their questions to Hyodo Sensei.
To be notified of up-coming #AskSensei webinars and other events, sign up to our eNews mailing list at the bottom of this page.
Up-coming #AskSensei Events and Registration
For further information about the #AskSensei webinar series, please refer to our #AskSensei overview page.