Dear All,

I have come across questions regarding improve phase where participants want to know specific techniques for how variation can be reduced.

• Fixing the obvious based on knowledge of a dominant cause of variation. This may include mistake proofing or removal of a vital X (if it is NVA).
  
• Desensitizing the process to variation in dominant cause.
  
• Feedforward control based on a dominant cause.
  
• Feedback control.
  
• Making the process robust to variation in causes.
  
• 100% inspection (automated is better here) or increased inspection.
  
• Moving the process center closer to the target (in case target is center of specification limits).
  

If you want to discuss any of these in more detail, do post messages.

These seven approaches can be used either in improve phase (to reduce variation and increase sigma level) or for process control in general (even if you are not doing a six sigma project)

ANUBHAV GUPTA REPLIED TO THIS TOPIC

 

Although the mail was not meant for me I can throw some light on this.

 

Desensitizing the Process to variation in the dominant cause is just like elimination a factor from the vital X. For example a paper gets torn by pen pressure which is then a Vital X we have modified the process to make paper double layered and now the pen pressure is not a vital X i.e. either it does not effect the paper at all or the coefficient of correlation amongst tear property and pen pressure has reduced drastically say from 0.9 to 0.02

 

Secondly, feedforward control refers to the correction we send to the output when we know that there is a particular shift in the result. e.g. if we are producing a salt solution to be packed in bottled at 10% concentration and a new process introduction has made our resultant solution to 9% instead of 10%. Hence we have two option. one is to monitor the concentration of output and vary input accordingly to achieve 10% (this is feedback, where we change input) or we just add another 1% of salt to the output solution (this is feedforward where we monitor output and accordingly alter the output itself and not the input).

 

I hope this throws some light on the approach of these improvement techniques.

 

Regards,

Anubhav Gupta

Process and Systems Improvement Manager

Lancashire Double Glazing Ltd.

Preston, UK

Dear Sir,

 

I am in the field of manufacturing of Consumer and Industrial Electronics

 

I want to discuss the point of 100% inspection in the process. Also you have suggested a automated Inspection. This automated inspection seems to be costly in comparison with all other approaches. This automated inspection is mostly used in higher level product like motherboards, Cellphones and other critical applications. Automated inspection is not possible sometimes on the product level.

 

Also 100% manual inspection is very difficult and time consuming (manpower cost also involved) when product is of high volume and low end (small components but in thousands)

 

Please suggest in this case.

 

Thanks & Regards,

Pankaj Bansod

Customer Quality Engineer

Celestica (India) Pvt. Ltd.

Hyderabad, India

Dear Pankaj,

 

There may be several means to automate inspection in a process. Some of these options may be expensive but it may be possible to devise novel methods of inspection based on the physics that need not always be expensive.

 

You could get some ideas by inviting different suppliers of automation instruments to see if they have any better ideas. Benchmarking with your competitors or similar processes in other industries may also provide ideas for "cheaper" ways to deploy automation in a process.

 

SJ

Dear Pankaj,

 

Taking this discussion further, if and when applicable, option 1 and option 2 (among the seven ways given at the top) work out as better choices as compared to 100% inspection. Prevention is better than cure.

 

As we all know, inspection is some times unavoidable (whenever we fail to find a perfect mistake proofing option)

 

VK

Dear All ,

I joined to day & found this topic here, which is very interesting for me as well.

As You know any inspection is NVA and it must be eliminate. 100% inspection for me is a disaster. I would interested WHY? (5x). It is better if we are controlling the INPUT parameters then OUTPUT ! Theoreticaly 100% controll (f.e.: PFMEA, POKA-YOKE, AUTONOMATION) about ALL input parameters is ZERO DEFECT ?! But what about the noises ? Is the design enough ROBUST ? (DFMEA, DOE, Transfer fuction, Taguchy, ect.). I would like to propose for Pankaj to set up a ROADMAP to eliminate the 100% control. May be we can discouss it here .

Just to bring about a discussion, I would opine that inspection is not all bad. In the Lean philosophy, we rely on inspection to ensure that only good quality product is passed on to the next step in the process. If there are two steps in the process A followed by B. Then A inspects incoming material, does his work, inspects it to make sure everything is okay and then sends it to B. B follows the same process of inspecting the part that he/she has received, does work, and then inspects again before sending it out of his/her area. Quality at the source is very important and even if we have perfect processes, Poka-Yoke etc, we still need to spend maybe a few seconds at least to inspect incoming and outgoing work.

Your thoughts on the above?

I think all inspection is waste. Because therefore we breaking the continuous material flow & inspection is not value added activity (if the customer not pay for it). Why we have to perform any kind of inspection (incoming/outcoming) ? Because we are not sure that the previous step/motion is 100% perfect. 100% perfection (Zero Defect) is pending mainly on the robust, perfect design & secondly on source inspection (fool proof solutions). Successive inspection (defect found at the next process stage) not so successful.

The first step would be in any case of new products (manufacturing) to perform a proper TRIZ/(TDFSS)/DFSS. After that the manufacturing is much more easier & PSS (process six sigma) may be not needed !   (TDFSS:Technology Development for Six Sigma).

Waiting for Your reply.

Let me take this discussion little forward...

Sirs, I agree that any kind of inspection is completely NVA. Now as inspection/ monitoring or auditing would definitely involve some feedback ....can we say then feedback as an activity to correct the process further, to control the possible variation would also be NVA and therefore is not a good mechanism of controlling a process?

looking f/wd for your responce,

sir

 I am not agree with 100 % inspection  Except fewer ones like Aerospace parts Manufactering. But we can not avoid inspection. Can Any customer will accept parts If we say that we have done Poka-Yoke on inputs & on process but not done any Inpection on Products?

To arrest the Variation on Final Product ( As we can not elinimate Machine Vibration,Power Flatuation, Temp Variation but we can control it till some Extent),Inpection or audit/ Product Validation is required to some extent. it also help us to  collet data for correction/ action to facilate continious Improvements.

VK/ SJ sir-- Your coment Please

 

 

Dear Partha,

Zero inspection is a philosophy practiced by Toyota who are known for their world class performance and capabilities. They use Total Quality Management and Just-in-Time concepts.

Suppliers are trained by their customers in quality management. Supplier quality becomes so reliable that their raw material can go straight to the customer's production line for immediate usage without the need for inspection and storage.

By training all suppliers and operators to do their work right the first time, high quality at all stages can be achieved, thus making it possible for the company to reduce and eventually eliminate all forms of inspections. Zero inspection will subsequently result in lower operating costs, shorter manufacturing lead time, and lower inventories.

However, although the 4th option suggested above by VK, is an approach to reduce variation but it may not be effective as any kind of feedback follows a path which in- turn takes its own time, may lead to caliberation issues between the 2 operators (giver and taker) and finally leads to rework. All three are non value add!

 

No doubt that Inspection is a NVA but we all know that NVA can also be further categorized as avoidable & unavoidable. So where ever possible to avoid or reduce , it should be done otherwise we also know that in many cases like aerospace industry, it can not be eleiminated.  So the debate over it will not yeild much insights.

Regards

sanjay bishnoi 

 

Dear All,

I think all are following philosophy,

But remember, If you can't measure, You can't Manage...

Inspection is to make sure you are 100% thats it.

Thsi applies not only Aerospace...

Hi All,

 

Automation is the best way for reducing defects... People say, automation is costly... But there are automations which can be derived at very cheap rate...

For example we had a problem in Watch Strap Assembly... Gap between Watch case & strap... Wrist watches The strap is of rubber... Its very difficult for a person to push the rubber strap against the case & 2 screws has to assembled in pressed condition...

 

We made a small fixure (Rs.3600/-) which will hold the watch case against a wall at one end and at the other end a spring assembly will push the rubber strap against the case automatically... The operator can just assemble 2 screws... The FTA improved from 62% to 100% & lead time of assembly came down from 4 minutes to 1.5 Minutes per watch. Alternate solution of using a CNC/NC operated machine for this activity would have costed upto Rs. 2Lakhs.

 

Automation is normally mis-understood by people as a costlier solution... For some operation like in Electronics assembly (Mother Board)... automation can be costly... But a clear understanding on ROI can clear our doubts...

 

In automation, Production time & Inspection time fall parallely... Hence the cycle time is same as the production time thus reducing NVA & hidden factories...

The Kaizen sheet is attached in the file cabinet... You can have a view..

 

Ramabadran

Hi Anubhav,

 

When can the Desensitizing the Process to variation in dominant cause be applied?

As I feel this concept is costly because of huge investment for example paper layer has to be changed when pen pressure is damaging the paper?

can you please give some more examples.

 

Guru

Hi All,

I agree with shalini, controlling the supplier quality is huge task and we should have a robust process in place.where ever possible the poka yoke should be made available.

Hi Pankaj,

we have to focus on automated inspection which is free from human inspection. any management will agree if you show the threat for the business due to bad quality product and cost of poor quality.

Dear All,

 

To day i have joined in the this discussion. I agree with Anras's view of ZERO DEFECT defect, where the INSPECTION is an absolute NVA. From own organisation view point we should focus to eliminate internal inspection of any short.

 

For incomming inputs the suppliers QA and claim procedure in place with a robust agreement of supply. Whereas for own products our process should capable enough of making 100% defect free product. Now you invest in technology or else use your smart engineering that's organisational freedom. We may have to develope supplier of that calibre ensuring POKA YOKE is fully implemented. I think We should not compromise on our demands from our supplier.

 

Your View Andras.

Prashant

I agree with Ramabadran on automation as an alternate for inspection. Automation not only eliminates possibility of all known errors as per FMEA but in some cases, it also gives the business an accurate and timely data on instances of variations (possibly due to external/unforeseen factors). Since Manual inspection is not a foolproof mechanism, the data it may provide can mis-lead the business. Hence Poka-Yoke should be effectively used and automated inspection should not be considered as NVA.

Would appreicate thoughts from all of you on this.

Regards,

Ashish

Controlling supplier Quality defects can be controlled through FIRE WALL in the system @ Supplier end, and having agreement of inspection ( AOI ) with supplier