Control charts - In process Inspection

[krishnamurty_madduri]

Hi,

For In process Inspection: we want to use

a. Inspn points (type 100) a

b. have single recording of 5 to 10 individual readings per sample

c. have a control chart per Inspection point with control limits and action triggering

d. It should show the values per reading that was recorded. Scale should also show that...

I have gone through some of the posts on this topic but.. it looks like:

1. SAP doesn't seem to consider individual readings for Inspection points.

2. Only Mean values (of all the 5 or 10 readings) per Inspn point are shown in the graph

3. The graph shows time scale (with time for some years! or some big numbers in default).

4. With so many charts listed and each one differing with the sampling procedure, it becomes rather difficult to choose from... (probably, you need a lot knowledge in Statistics!)

Whereas, the Run chart is comparatively simple,  takes & shows  single results in graph but, we want control chart!

Any help please ?

Regards,

KrishnaM

[krishnamurty_madduri]

Hi Craig,

Thank you for clarifying the point.

But, my client wants:

1. To record results for the same characteristic in an hourly basis in the In process Inspn.

Hence, we thought of using Inspection point.

2. They want to see that the readings (results) don't cross the 3 sigma limits in graph.

3. In case the readings (results) cross the limits: the system should trigger a notification. (We could do this with the Defect recording -->Notification activation)

Simple Run charts seem to be more easier to use for the end-user.

Do you think individual multiple samples would be of some help ?

Please guide.

Regards, KrishnaM

[former_member42743]

So wouldn't this be an inspection point every hour with one result recorded?  CS

[krishnamurty_madduri]

Well.. it would be  one inspection point per hour, with about 5 samples. (Ex. Temperature of a plating solution in tank, taken at different places). Regards, KM

[former_member42743]

OK, yes, then 5 individual results per inspection point which average together for your hourly result which is plotted on the SPC chart. With upper and lower warning limits set you should be able to achieve what you want.

So you are saying you haven't gotten this to work yet?  It should be all standard SAP.

CS

[krishnamurty_madduri]

I am getting the mean values of individual inspn points (as mentioned by you earlier) in the chart. But, my requirement is: is it possible to get individual graph per inspn point ?

KrishnaM

[former_member42743]

No. within an inspection point I don't believe so. 

And in your example, (5 temp readings in a tank), what does that do for you?

Craig

[krishnamurty_madduri]

OK. Thanks. Can someone else share their experience in using Control charts ?

KrishnaM

[former_member42743]

This doesn't sound right:

"c. have a control chart per Inspection point with control limits and action triggering"

Your control charts are usually created across inspection points.  You don't have a chart for each inspection point usually.

An inspection point is typically a single sample taken at either a time point or after a certain quantity.  When you record multiple results within an inspection point for a characteristic you are usually recording multiple test runs of the same sample which are than averaged to give the value plotted to the chart. You don't chart these.

CS