R
RMedrano
We have a process that is being transferred into our facility.
This process has been running at our sister facility for a long long time.
Some time back in 1997 they had a huge push to use SPC. Seems that they went hog wild and are charting anything and everything.
We have a process coming in that makes a part similar to a washer, the part print lists the Inner Diameter and the outer diameter for this part as a Key characteristic.
The problem is that the parts are not perfectly round, so at some point you have a max and minimum diameter..its not very consistent all the way across the part.
After looking at the current data collected by our other plant I have determined that the charts they are currently plotting are completely useless. They have 2 charts one for ID and one for OD. The problem is that they take a min and max of each and plot it into the same chart. This basically shows up as a chart thats running pretty much right down the middle, and the histograms for capability look like the letter M totally bimodal split towards each end of the spec.
My first thought is to take each dimension and seperate the Min and Max into seperate charts. So there would be Min ID Max ID Min OD Max OD. My question is this though.. would I need to treat each of these like it was a one sided specification? If i use the total tolerace for the ID and OD on each chart the data is still going to be skewed towards one side.
Is there a better way to monitor such dimensions on parts that are not round?
This process has been running at our sister facility for a long long time.
Some time back in 1997 they had a huge push to use SPC. Seems that they went hog wild and are charting anything and everything.
We have a process coming in that makes a part similar to a washer, the part print lists the Inner Diameter and the outer diameter for this part as a Key characteristic.
The problem is that the parts are not perfectly round, so at some point you have a max and minimum diameter..its not very consistent all the way across the part.
After looking at the current data collected by our other plant I have determined that the charts they are currently plotting are completely useless. They have 2 charts one for ID and one for OD. The problem is that they take a min and max of each and plot it into the same chart. This basically shows up as a chart thats running pretty much right down the middle, and the histograms for capability look like the letter M totally bimodal split towards each end of the spec.
My first thought is to take each dimension and seperate the Min and Max into seperate charts. So there would be Min ID Max ID Min OD Max OD. My question is this though.. would I need to treat each of these like it was a one sided specification? If i use the total tolerace for the ID and OD on each chart the data is still going to be skewed towards one side.
Is there a better way to monitor such dimensions on parts that are not round?
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