Is this sampling method tighter than before?

[blueearth99]

Original sampling method :
every batch (100 samples) select 5 to inspection.

New sampling method :
every batch (20 samples) select 2 to inspection.

Is new sampling method tighter than original one? Why?

 

[ajack1]

Well yes it is tighter in the fact that you now need to inspect 10 samples for every 100 produced.

Obviously I can only guess at why but possibly this is a part with tight limits and the settings need to be tweaked in order to stay within upper and lower control limits. In the first case you could run 95 parts between inspections where in the second case it is only 18 so smaller changes are made more often.

Again my guess is they want zero defects without 100% inspection.

 

[blueearth99]

Thank you ajack1.
Our machine is not very stable,so I want to ask them to tight the inspection.

 

[DennisP]

Coming from a machining and quality background, wouldn't it be better to find a way to stabilize the process rather than rely on inspection to insure good parts? Have yopu performed a capability study to determine whether or not the machine is capable of running the part with good control and within the limits? Prevention is almost always cheaper and better than detection.

 

[blueearth99]

Thank you Dennisp
you are right,fix the machine is the better way.
we have had a plan to get a new more stable machine.