Pass Through Rate Ratio Improvement and Defining Pass Through Rate

[qsmso]

Dear Cove’s friends,

I conducted the internal quality audit at the final inspection section. They have the quality objective “ 95% pass through ratio”. Their work is only inspecting the product that come from previous process. So, I am confuse that

1. What does it mean for pass through rate? For the current formulation is
Pass through ratio = (total passed product / total inspected product) * 100

2. How can they define their quality objective like that since I have seen none of value added from this process? So, in my imagine, if I would like to achieve the target, fine, just let every pass (OK)

3. The current result is the target is not being achieved, so, I am wondering that what should be the improvement plan for them to achieve the target?
Any comment?

Regards,
QSMSO

[E Wall]

QSMSO, What did they respond when you asked those questions during the audit?
Each location will have their own process, but in general I would presume there is some documented Final Product specification or criteria to inspect against. Also, are any records being maintained?

Maybe I am confused with the term pass through ratio as it applies to final inspection. Does it really mean that 5% scrap is allowed to leave or are they inspecting 95% of the product.

Either way way it is at the least counterproductive and at the most means 5% bad parts go to the customer. (50,000 PPM)

Maybe some more clarification??????

[CarolX]

Hello qsmso,

Are your referening to an acceptance rate...that is 95% of the product is accepted on original inspection? If this is what the goal is, one question I have is why is this a "Quality Objective"? Final inspection didn't produce the parts, so how can they be responsible for an unachievable goal???

Perhaps you could provide us a little more info...

Regards,
CarolX

[qsmso]

Thank you for all responses,
I did check with the final inspection area again, they issisted that the formulation to calculate pass through ratio is

Pass Through Ratio = ( Total OK / Total inspected ) x 100

It means they want to monitor previous processes' performance.
95 % pass through rate means only 5 % they allow for NG products from provious process. They inspect and separate those NG prior to deliver to customer.
But what I also do not understand is what kind of method they can apply in order to achieve 95 % pass through rate without any support from previous process, who actually make root causes of NG.
What I comment for them is to make good analysis report about type of defect they detected and souces where those NG coming from, then report to management.
Any comment?

[CarolX]

Sounds more like a company objective than a department objective. The only thing final inspection can do to raise the acceptance rate is to not inspect product and plead ignorance. Begin an analisys of the reject reasons and try to identify trends. Report those finding to the responsible department, get some CA commitment, and then see what happens to your acceptance rate.

Regards,
CarolX

[goose]

Follow the grandma's lead.

We had similar situation where "first pass yeild" was 90% aprx. Used a greenbelt team to do historical analysis of the 10%. Segmented and stratified data and learned that vital few contributors to defects were assembly errors, vendor errors and design issues.

Established feedback loops to departments causing defects. Formed "mini" teams to attack repetitive issues.

Project not complete but in 4 months over 60% improvement.