Quality Control - Before or after?

A LinkedIn forum question asked for a laymen’s explanation as to why QC Inspection is not a way to ensure accuracy of the end product.  As usual, responses from others were lengthy and not necessarily directed at answering the question.  This includes one I had posted approximately 30 days earlier, when I must have been upset with some of the responses.

If a defective product was made, inspecting it at the end of the process does not make the product any less defective.  So now it has to be scrapped (or if a simple defect reworked).  Who is paying for this?  Is this not one of the forms of waste?  Is this not what we are suppose to be continually improving, the elimination of waste? When waste is created, in any form, the true value is lost and the customer ends up paying for the value + waste through higher selling prices that cover the accepted projected loss of the manufacturer.  This is what opens entry to market, giving competition room to squeeze between you and the customer, eventually taking your business away.

The purpose is to make it right the first time.  Quality at the source and the responsibility for that quality comes from the person adding the value which is the operator.  And I must emphasis here, WITHIN THE PROCESS THE OPERATOR WAS GIVEN. If your process has been setup to manufacture the product to customer specification, and the process is statistically in control, then there is no need to inspect the end product right?  The process is the process, good or bad.  The process data is what "speaks" back to the operator indicating whether the process is in statistical control or not, and the operator is to react when it is not in control, eliminating the chance of defects.

Now, if you are saying defects will still occur in a statistically controlled process, then so be it.  That is what the process was designed to do.  You need to change the process to reduce (eliminate if you can) the defects.  You need to identify the defect and root cause.  You may need to reengineer the product for manufacturability so defects cannot be made.  You may need to revisit the PFMEA and add a poka-yoke on a value added feature the operator has difficulty maintaining.  You may need to revise the standardized work to add quality check points.  There are many things you can do, however realize it comes from the process and that is what needs to change.  Please understand what you want to do is to change the system or it's processes to aid the operator in creating the value and reducing (if not eliminating) waste.

As I read the aforementioned forum question and responded as best I could in laymen terms (there is always room for improvement), I thought of problems with processes I have encountered in automotive.  I would estimate 60 to 75% of the process issues were caused by variance from incoming material, which the process was not designed to handle.  As I usually do I asked Why? maybe 100 times (okay, perhaps a bit of an exaggeration, however subconsciously I have drilled down through a lot of Why’s and I am zeroing in on root cause before I consciously think of the second or third Why?).

As I thought through this I realized, during product development companies hand make parts, do one off samples, 200 or 300% inspect prior to shipment, basically producing the perfect part.  Even through the different build events special qualified personnel are making the product.  Eventually the product is made off production tooling, still then by specially trained production personnel for pre-builds and line fill.  When mass production hits all of the “special handling” goes away, and you merge into the “true process” from not only your process but also from your suppliers.

What is supposed to protect the customer after product launch is the PPAP (production part approval process).  This is a warrant that the supplier process is capable of providing what the customer is paying for, whether it is volume of product or any fit/form/function of the product as specified by the customer.  How does this tie back to material creating havoc with the process and the potential of defects at the end of your production line?

Discussing this with my son Nick, one possible cause might be that during the initial trials and preparation for PPAP, not all of the supplier variations in the process were uncovered.  Perhaps the FMEA was not detailed enough.  Perhaps the supplier did not understand the process well enough to even contemplate a potential failure to put in the FMEA.  Perhaps the supplier kept making the "perfect part".  Whatever the case, when variation occurs that upsets the process, it must be identified and eliminated.  The intent should always be to provide materials that maintain a stable, statistically controlled downstream process.  If during mass production something is uncovered, fix it.  Don’t accept from the supplier, “Well it was PPAP’d that way and you accepted it.”  Go back and review the process, the FMEA, and update it with the new information so changes to the process take place that accommodate “the intent” of the PPAP, which is to make a defect free product from the process.

Quality control does not take place at the end of the line, nor at the beginning whether incoming material or something else.  Quality control is a constant effort in maintaining a statistically controlled process, identifying variance that was not originally considered in the process, and eliminating process variance that creates defects or defective products.

Okay, now let us get back to reality.  We all know quality inspections at the end or any other part of the process are not going away.  Why is that?  Quality inspections at the end of the process is just an admittance you do not understand the process nor if it is in statistical control.  This is no different than using kanbans.  A kanban is an admittance you do not know how to go to once piece flow yet.  You know one piece flow is what you need to do.  You just do not know how to get there yet.  So the purpose of all this writing becomes a "strive" for no inspections at the beginning or end of the process.  A "strive" for one piece flow, a "strive" toward continual improvement.  If you do not set the bar for "no end of line inspection", "no kanbans", then you will always fall short and the next company that figures it out will be more than happy to close your business for you.