Does source inspection result in zero defects?

[toniriazor]

Hello all,

Has anyone read the book of Shingo Shigeo - Zero Quality Control(Source Inspection and the Poke-Yoke system?) What is your opinion on it?

I recently started to read that one, but somehow I feel some of the methods described especially with the source inspections and how the next operator in the process is checking the work of the previous worker and giving feedback if any defects occur are overexaggerated. It is difficult to believe that this could lead to zero defects or nearly zero. Maybe I am wrong. Time will show

 

[Miner]

I have that book and consider it to be excellent. One of the things that you may be missing is that Shingo-san is writing this as a journey toward zero defects. He starts with inspection and describes the problems then moves through 7 stages of approaching zero defects. When he covers Stage 7: Basic concepts for a Zero QC System (Note: this is not zero defects, but zero quality control), he mentions in item 4 that human workers are not infallible. Therefore, recognize that fact and set up Poka-yoke devices accordingly.

 

[Bev D]

Miner nailed it.
In addition, having worked in the Toyota environment I can add that source inspection will not find inherent or latent defects that are due to physics. It does find human errors and obvious ‘breaks’. Feeding this information back to the ‘source’ operator (not the guy at fault) is essential for early remediation of ‘broken things’ and learning for the operator and/or team lead/supervisor…It is very effective approach in the journey towards zero defects when done in a supportive environment and not in a “find out who to blame” environment.

 

[Miner]

In addition, it will only consistently detect those errors for which they are looking. Other errors will only be detected by happenstance.

 

[toniriazor]

Ok, thanks for your input. Useful to know that is a good read and will bring new ideas and knowledge. Great! I will update my feedback, as I finish the book in the next week.

 

[Mike S.]

Haven't read the book, but as others have said, there is no such thing as zero defects over the long haul, only approaching it. But that doesn't take away from the journey.

 

[Randy]

No such thing as zero defects

 

[Bev D]

Well that’s what we’ve been saying and what the author says actually.

 

[toniriazor]

Today I finished the book.

It is true that Mr. Shingo Shigeo is developing the idea throughout the book, that through different inspection methods and even poke-yoke, zero-defects cannot be achieved, because it is inherent to any system/process/operation to fail at certain point. However he also clarifies that the error and the defect should not be confused and that through the varieties of inspection methods (successive check, self-checks) the defects rates can be decreased dramatically. A note here that he encourages that the operators are doing the inspection, not a dedicated person after the processes.

The author also explains why he believes that SQC (Statistical Quality Control) methods are not so effective as the source inspection methods, because the SQC data is reviewed and analysed sometimes too late when the defects had already caused trouble, while during source inspection methods the feedback is immediate and actions taken promptly.

There are many examples of the use of Poke-Yoke devices and how different and relatively cheap gadgets were integrated into the processes to improve the built-in quality. This part of the book is very informative and most of the drawings and explanations can be understood.

Finally it is discussed how the QC activities were developed and why.

I think this book is a good read.

 

[Bev D]

Today I finished the book…

The author also explains why he believes that SQC (Statistical Quality Control) methods are not so effective as the source inspection methods, because the SQC data is reviewed and analysed sometimes too late when the defects had already caused trouble, while during source inspection methods the feedback is immediate and actions taken promptly…

It is a very good book that explains the source inspection method very well.
The only caution is the negative perception of “SQC”. SQC and other methods are intended to detect, investigate and solve physics related problems that are not human error based. Source inspection and poke-yoke is perfect for this bu these things cannot address physics based problems. That requires a completely different set of tools. Most companies experience booth types of problems…