SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 components

[f1guru]

Help, our company is new to having to do any type of spc but a new customer is requesting spc on some parts we are doing for them, does anyone have any excel spreadsheet formula for a sample size of 40 components that i can have a look at.......

 

[Jen Kirley]

Re: spc

Welcome to the cove!

I did a search in the Post Attachments List (see the green button in the header) using "SPC" key word, and was returned this list to look through.

To see some similar discussions you can view their links near the bottom of this page.

I hope this helps!

 

[harry]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

Also check - Bob's blog

 

[Miner]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

Is there a particular reason why you would want to create a rational subgroup that large?

While subgroup sizes this large are possible, rational subgroups of this size are very rare. SPC beginners often err by creating non-rational subgroups that are too large.

 

[f1guru]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

Yes our customer had requested that spc has to be done on the first batch of 40 components so this is what we have had to do!! Thanks for the posts i used one was on a earlier post its our first foray into aerospace work (which will hopefully be our last) so having to do this stuff is a nightmare bring back motor racing!!!

 

[bobdoering]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

Help, our company is new to having to do any type of spc but a new customer is requesting spc on some parts we are doing for them, does anyone have any excel spreadsheet formula for a sample size of 40 components that i can have a look at.......

What kind of process are you trying to implement SPC on?

 

[f1guru]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

they want it on diameters, surface finish and perpendicularity

 

[bobdoering]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

they want it on diameters, surface finish and perpendicularity

Are these precision machined diameters? If so, you would use the X hi/lo-R chart and sample 1 part at a frequency determined by your capability study. A sample of 40 parts would be meaningless, and an X-bar R chart would be a waste. It may be OK if you are not precision machining - such as drilling.

Now, unless your perpendicularity and surface finish are horrible, you also have a beta distribution on those characteristics - that is, non-normal. This is from the physical limit of 0 (perfectly smooth, perfectly perpendicular.) Again, it is difficult to understand why you would want a 40 pc sample for those characteristics. On these you might try a X-bar R chart. The only thing is the "mean" will not be centered.

 

[Bev D]

Re: SPC Newbie looking for Excel Spreadsheet formula for a sample size of 40 componen

f1guru: Can you clarify what you mean by "SPC on the first batch of 40 pieces"? this is strange even for aerospace companies, UNLESS the pieces are very large and they are looking for 'short run SPC' within the batch. perhaps they are looking for a capability study accompanied by a Gage R&R?

I assume you are measuring all 40 pieces after they are manufactured? or in-process?