MSA 4th edition reference manual - Page 120-121 Clarification

B

Black arrow

Hello,

When i read about the reference figures concerning how to determine the process variation page 120-121 in reference manual MSA 4 th edition i need some help to determine what this mean:

1) using process variation
-process variation , taken from parts in the GRR study itself
-use when selected parts represents the expected process variation (preferred option)

2) surrogate process variation
-use when sufficient samples to represent the process are not available but an existing process with similar process variation is availble.

3) Pp (or Ppk) target value
-use when sufficient samples to represent the process are not available and an existing process with similar process is expected to have less variability then an existing process.

4) Specification tolerance
-when the measurement system is to be used to sort the process, and the process has a Pp<1.0.


Correct me if i am wrong but option:

1) means % Study Var in Minitab
2) means option % Process in Minitab. (Historical standard deviation has to be entered)
3) means also % Process in Minitab (Use standard deviation from a new process with a less variability)
4) means % Tolerance

Thanks in advance!
 
B

Black arrow

Hello,

Sorry for "pushing" this topic. Would like to have some comments concerning my questions above, thanks in advance.
 
B

Black arrow

Hello again,

Can anyone please make some coments concerning my question above?

Thanks!
 

Miner

Forum Moderator
Leader
Admin
Hello,

When i read about the reference figures concerning how to determine the process variation page 120-121 in reference manual MSA 4 th edition i need some help to determine what this mean:

1) using process variation
-process variation , taken from parts in the GRR study itself
-use when selected parts represents the expected process variation (preferred option)

2) surrogate process variation
-use when sufficient samples to represent the process are not available but an existing process with similar process variation is availble.

3) Pp (or Ppk) target value
-use when sufficient samples to represent the process are not available and an existing process with similar process is expected to have less variability then an existing process.

4) Specification tolerance
-when the measurement system is to be used to sort the process, and the process has a Pp<1.0.


Correct me if i am wrong but option:

1) means % Study Var in Minitab
2) means option % Process in Minitab. (Historical standard deviation has to be entered)
3) means also % Process in Minitab (Use standard deviation from a new process with a less variability)
4) means % Tolerance

Thanks in advance!
1) Correct
2) Correct
3) Minitab does not have this exact option. You would have to manually calculate.
4) Correct
 
B

Black arrow

Hello again,

From a recently made MSA: The parts we selected were not representative for the normal process varariation for this part. We would like to use approach nr 2 " surrogate process variation" mentioned above and we have earlier made couple of cap.studies with this part involved.

When it becomes to calculating % Process in Minitab, should we enter standard deviation mentioned overall or within ?

Thanks!
 

Miner

Forum Moderator
Leader
Admin
If your process is well controlled, it shouldn't make a lot of difference. The overall standard deviation (provided the process is under control) would be the most representative of your process.

Also, method #3 uses Pp, which is based on the overall standard deviation, so that would be consistent.
 
Top Bottom