How to compute Control Limits for Stability tests?

D
#1
Stability tests

I need to know how to calculate control limits for stability tests. Any experts?
Thanks ahead of time !!
 
Elsmar Forum Sponsor

Marc

Fully vaccinated are you?
Leader
#2
I'm posting a reply to 'light the bulb' - maybe attract a reply. I'm not a statistical person. If you get real needy, e-mail Howard Atkins - he's the moderator of one of the forums. He's pretty statistical.

Anyone have an answer for here?
 
D

Don Winton

#3
Dawn,
I may be able to help, but need more info. Can you provide additional details of your requirement.

Best Regards,
 
D
#4
I am writing a procedure on claculating stability. When I read in the MSA book a calculation which I don't have with me right now, but I was confused as to how to claculate the control limits. We have started stability tests on a chart, and it is a regular Xbar chart. We need to calculate the control limits to get an accurate range of the readings. Does anyone know of SPC programs which will give you the actual stability of the master part?
Thanks for the help!
 
D

Don Winton

#5
Dawn,

You have started stability tests using a “regular” Xbar chart. However, you did not mention a chart for dispersion (R, s, sigma, etc.)?? Assuming a dispersion charts exists, then the calculation of the limits is straightforward for a “regular” control chart. If a chart for dispersion does not exist, that is another matter.

Control limits do not give an accurate range of the readings. Rather, the purpose of control limits is to determine when a process is in or out of a state of statistical control. A process can be in control and still not be stable. Perhaps you are referring to process capability? It sounds, however, that what you are trying to do is not typical. Perhaps I am still missing something. Additional details may be required.

There are many SPC programs, but I prefer Statview with the QC module installed.

Best Regards,
 
D
#7
Thanks Don,
We have a customer who wants us to perform stability tests on every gage we use to machine their parts, including micrometers. We do not have an SPC program which calculates stability.I have discussed this with someone and was informed to use moving range charts and we should be ok with that. Haven't tried it yet. Thanks!!!
 
D

Don Winton

#8
Dawn,

Be sure to discriminate the difference between “stability” and “statistical process control.” I would suggest that your customer does not know the difference, either. Rather than stability tests, would not repeatability and reliability (R&R) tests be more suitable? Maybe, Maybe not.

Best Regards,
 
Thread starter Similar threads Forum Replies Date
G How to compute or estimate a micrometer or caliper flatness using optical flat General Measurement Device and Calibration Topics 2
R How do I extend Correction factor of Calibration cert to compute instrument accuracy Measurement Uncertainty (MU) 1
M Using Minitab to Compute & Compare the Mean and Standard Deviation Amount Using Minitab Software 7
D How to Compute the Accuracy Class for a Weighing Scale? General Measurement Device and Calibration Topics 4
D How to compute the Permissible Errors for Class 2 Weighing Scale General Measurement Device and Calibration Topics 2
Q Accuracy: Is there a specific formula to compute Measurement Device Accuracy? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
B Minitab v15 Precision to Tolerance does not compute? Using Minitab Software 1
R Method to compute Cpk for Attribute Data? Capability, Accuracy and Stability - Processes, Machines, etc. 3
D How to Compute "Inventory Turn Over Time" - TS 16949 Clause 7.5.5.1 IATF 16949 - Automotive Quality Systems Standard 5
D Is it acceptable to use S bar to compute CPK? Capability, Accuracy and Stability - Processes, Machines, etc. 1
G The basics of how to compute Productivity in a company Manufacturing and Related Processes 7
D Stability, Linearity vs. Bias - Do we need to compute them all? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
A Precision/Tolerance Ratio for 1-sided Specification - How to Compute Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
L What is the standard method used to compute Attrition rate Misc. Quality Assurance and Business Systems Related Topics 9
M Attribute MSA-CrossTab Study Example in MSA Manual:How to compute the Expected Count? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
T More GD&T - We can't compute Cpk using GD&T Capability, Accuracy and Stability - Processes, Machines, etc. 2
Crimpshrine13 Bulk Process (Electroplating), Control Plan, and Process Change IATF 16949 - Automotive Quality Systems Standard 0
giavannatabbs ISO 9001:2015 Control of Records - QMS Communications? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 9
A Introducing a document control system benefits Document Control Systems, Procedures, Forms and Templates 5
N Effective use of a Risk Register - Bumper sticker or Mission Control ? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 16
L To control the essential design outputs Medical Device and FDA Regulations and Standards News 4
G Root cause for outsourced pest control service not in approved supplier list ISO 13485:2016 - Medical Device Quality Management Systems 4
A Digital Document Control - Revision ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 13
O Process Flow Diagram, DFMEA, PFMEA, Control Plan integrated softwares FMEA and Control Plans 4
V Over 60 dimensions CMM measurement in control plan APQP and PPAP 7
A Document control system for QMS in Google Drive? Document Control Systems, Procedures, Forms and Templates 6
V Opinion on gauge control graphic General Measurement Device and Calibration Topics 5
S ISO 14001 Operational Planning and Control - Proving evidence of communicating environmental requirements to suppliers ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
V How to control odour outside paintshop ISO 14001:2015 Specific Discussions 1
G FMEA versus control plan IATF 16949 - Automotive Quality Systems Standard 6
K ISO 2859-5 (single run production) control plan issues FMEA and Control Plans 2
E Control Charts ISO 17025 related Discussions 7
E Control of Sterile Barriers made by the supplier Design and Development of Products and Processes 4
E Do anyone have document of automotive production risk and control of risk? Lean in Manufacturing and Service Industries 1
M X-MR Control Chart Rules (Particularly the MR) Statistical Analysis Tools, Techniques and SPC 3
I Clinical study suppliers (service providers) -- extent of control ISO 13485:2016 - Medical Device Quality Management Systems 4
P Product Requirements Control during Design Changes Design and Development of Products and Processes 4
T Control Excel template Document Control Systems, Procedures, Forms and Templates 5
J Document Control of Online Management Software ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 10
R 8.7 Control of Nonconforming Outputs AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 2
W Document control Document Control Systems, Procedures, Forms and Templates 10
S Control plan - Multiple batches Manufacturing and Related Processes 2
Q Control Plan and the frequency of sampling FMEA and Control Plans 11
A ISO 9001:2015 8.5.6 and 7.5.3 Document Control Questions ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
qualprod Sheets into a spreadsheet document control ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 4
Rene Minassian Control of (TMME) Testing and Measurement Equipment Oil and Gas Industry Standards and Regulations 2
C Control Plan APQP and PPAP 7
D Control of Records ISO 13485:2016 - Medical Device Quality Management Systems 7
M Document Control - Applying Suitable Identification to Obsolete Documents ISO 13485:2016 - Medical Device Quality Management Systems 7
L Control of Documents ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 29

Similar threads

Top Bottom