Developing a Good Quality Metric

Six Sigma – iSixSigma Forums Old Forums General Developing a Good Quality Metric

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    The company I am working for has eliminated all inspection on the end product. I am looking for a sound tool to implement that will let me know what the quality is coming from the assembly area. A RTY has been mentioned but I do not know how effective this will be without a Third party person(inspector) collecting the data and not the assemblers. Does anyone have a suggestion on a tool that would work for this situation? 


    Andejrad Ich

    Take about a 6 x 6 inch piece of cardboard and divide it into a pie of about 6 to 8 sections.  Mark one section “0 defects” and the rest of the sections with other numbers of defects in any order up to the maximum amount of defects you would like to ever find in a batch of your product (if you don’t want to EVER reject a batch, make sure the maximum number is less than your allowable limit.  if you think it would be okay to reject some batches, then make one section HIGHER than your allowable limit).  Fix a free-spinning needle/pointer to the center of the board (test that it can spin around freely when you flick it with your finger).  When any batch of finished product is completed, just flick the needle/pointer and write down the number indicated by where the needle/pointer comes to rest.  Use that can be your defect rate. 
    Andejrad Ich


    Andejrad Ich

    (sorry…couldn’t help myself)
    seriously….the only legitimate replacment for inspection of process output is demonstrated control of all process parameters affecting acceptability of output.  You would need to see demonstrated control of temp, pressure, dwell, viscosity, moisture content, etc. to KNOW product is acceptable without actually inspecting it  (i.e., SPC charts for all contributing factors). 
    Andejrad Ich


    Duke Okes

    The other choice is to count how many products are returned from the customer, and divide by the number shipped.  You can subtract this fraction from any integer less than 4  to estimate how long you believe the company will last if it is not operating at a 6+Sigma level.  (sorry, also couldn’t resist)


    Jered Horn

    Okay…unless you know all the key process input variables that affect all the key quality characteristics of your end product along with effective controls in place on those KPIVs, the tool you need in your situation is “end product inspection”.



    I have a ton of questions as to why they did this without a plan. I have been through the same situation, let’s just say it is a good thing we didn’t build pacemakers or airplanes. I will not focus on what went wrong that is obvious. I will outline what eventually worked.
    Final inspection was not eliminated completely (It was very quickly determined this was stupid). We used auditors to conduct out of box audits. Finished goods that were ready to ship that day were selected at random (using a sampling plan) pulled from inventory and put through a visual inspection and final test. Any issues were immediately communicated back to the production line for process review and corrective action focusing on the process and training not the people.
    One of the key elements was training. You can tell everyone there are no more inspectors and you are now responsible for your own quality. But if you do not know what a defect looks like you will never see it. So we had to do allot of training on what the standards for quality are and how to identify defects.
    This eventually took the shape of process travelers that identified the key quality requirements (inputs and outputs) for each step in the process. Example: work instructions may ask the operator to verify that cable assy XYZ and 4 M3 screws are in the correct location before installing their own components.
    One of the key points here is the operators where assigned to outline these documents based on their best practice for assembly. Engineering played a support role to make sure they had a clear understanding of the product performance requirements and to develop whatever tooling they needed to make it happen.
    This was not a short term implementation we are talking a 5 year transition. Remember these are the people who were blamed for making all the mistakes. Now they were being asked to solve them.
    Since out-of-box audits is still sampling and not perfect. We developed a DPU tracking system to collect defect data during the build cycle. By the time we got to this point the trust between the operators and management had been significantly repaired. But there was still allot of training on how to identify a defect and what to do about it when you find one. So some rules were implemented that allowed the operator to fix minor defects as long as they were recorded to keep product flowing(again with more trainning). This data was reviewed on a weekly basis by production line management at the product and process levels. Causes and corrective action analysis was performed and the results reviewed by upper management monthly.
    Key point: Management review is in the form of what do you need from me to help you succeed in preventing this problem long term. NOT who, why, and how did it happen.  
    So where are we now Summary
    1. Detailed process documents that identify the key process variables and critical to quality and operation points.
    2. DPU data collection at the process step level with immediate and long term feed back for short and long term continual improvement.
    3. We still do out of box and end of line audits. However this is focused on new product deployment and customer complaints.
    We have gone from thirteen production lines with 1 or 2 inspectors each to only 3 people who are dedicated to inspection. 1 doing out of box audits and 2 handling Raw material and custom fab at receiving inspection. If you ask anyone in the facility who is responsible for quality they will say I am and explain to you what that means at their level in the organization.
    Regards and good luck
    PS. time frame for implementation 5 to 7 years and a complete upper level management change over.
    So why are they eliminating inspection again?$$


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