Process Qualification Sample size

Candi1024

Quite Involved in Discussions
#1
I am performing a PQ on process that has been up and running for quite some time, but it is a special process so it requires a PQ.

How can I determine a sample size? Reference docs would really help, hint hint :D
 
Elsmar Forum Sponsor
S

Scott A. Bednar

#2
Hi Candi,

Here is what I use when performing process qualifications. Sorry for the copy/paste. Hope is is readable. Shoot me an email if you need some clarification.

Best,
Scott


Sample size determination for process qualification and validations.

Confidence level and reliability % will be chosen based on risk analysis.

The following confidence and reliability levels should be used corresponding to the severity ranking from the risk document.

*Not many on the forum will agree with the C/R table below; too low or too high. The table that I am sharing is from a specific project at a former employer (medical device).

Severity (Confidence/Reliability)
CA 95/95
CR 90/95
M 90/90
N 80/90

Sample size for attribute data

Required Sample Size
Confidence Level
Reliability 80% 90% 95% 99% 99.9%
80% 8 11 13 21 31
85% 10 14 18 28 42
90% 16 22 28 44 66
95% 31 45 58 90 135
99% 160 229 298 458 687

Juran, J.M., and Godfrey, A.B., Juran?s Quality Handbook, McGraw-Hill, Inc.

Sample size for variable data when nothing is known about the process or its distribution

Required Sample Size
Confidence Level
Reliability 50% 70% 90% 95% 99% 99.5%
80% 9 12 18 22 31 34
85% 11 16 25 30 42 47
90% 17 24 38 46 64 72
95% 34 49 77 93 130 146
99% 168 244 388 473 662 740

Table X of Appendix II, Juran, J.M., and Godfrey, A.B., Juran?s Quality Handbook, McGraw-Hill, Inc.


Sample size for variable data when process average, specification limits, and process standard deviation are all known.

Use the one or two sided factors depending on whether the specification is one or two sided. The ?K? values in the table are determined from the following:
Minimum of (average ? LSL)/s, (USL ? average)/s
Where ?s? is the standard deviation and LSL and USL are the lower and upper specification limits.
When the ?K? value falls between 2 values of ?n?, round to the larger sample size.
 

Candi1024

Quite Involved in Discussions
#3
Thanks Scott, that's good stuff right there. I'm going to put that in my back pocket for later. This is in reference to medical devices.

Part of my issue is that the lot size is small, say 25 per run, 1 run per shift (It's a long process).

Do you think AQL sampling would be a reasonable approach to take? AQL typically is used for ongoing or incoming inspection sampling, so I'm unsure if its a reasonable approach.
 
S

Scott A. Bednar

#4
Do you have historical process data? Mean and Standard Deviation

What does your pFMEA and dFMEA say as far as risk level?

I am assuming that your product is costly and the testing is destructive?

Variable or attribute?
 
Last edited by a moderator:

Candi1024

Quite Involved in Discussions
#5
Do you have historical process data? Mean and Standard Deviation

What does your pFMEA and dFMEA say as far as risk level?

I am assuming that your product is costly and the testing is destructive?

Variable or attribute?
Do you have historical process data? Mean and Standard Deviation
-No


What does your pFMEA and dFMEA say as far as risk level?
-low


I am assuming that your product is costly and the testing is destructive?
-Yes, it is destructive testing.


Variable or attribute?
-I could make it either a variable or an attribute.
 
S

Scott A. Bednar

#6
Given your responses and not knowing much about the product, I would sample 16 from each production run over 3 days/runs. It may be expensive but that is the cost of doing business in some situations. You could take a look at the "sample plan analyzer" offered by Wayne Taylor (Taylor Enterprises). You could adjust your numbers from a risk perspective and possibly knock off a few additional samples. Contact me via email if you would like to discuss details about the process that you are not comfortable posting. Most of my process validation experience is related to plastics, injection molding, extrusion, post processing, cleaning, CNC (metals/plastics) and coatings (lubricants/drugs).
 

Bev D

Heretical Statistician
Leader
Super Moderator
#7
An alternative is to think of this as a process rather than a comparison of the new material to the old ( or to some specification) In PQ I tend to use control charts. this way I am not thinking about each lot as an isolated entity but part of a continuous process and my sample sizes can be substantially smaller.

If you have historical data we could help show you how sample sizes can get smaller and how you can use control charts.
 
Thread starter Similar threads Forum Replies Date
M Process Qualification - What is the recommended Sample Size for PQ? Qualification and Validation (including 21 CFR Part 11) 10
Q Determining the Appropriate Sample Size for Process Validation/Qualification Inspection, Prints (Drawings), Testing, Sampling and Related Topics 13
S Performance Qualification and Process Validation ISO 13485:2016 - Medical Device Quality Management Systems 5
V Process, component or full product re-qualification: leaded to unleaded solder Qualification and Validation (including 21 CFR Part 11) 8
E Equipment Qualification - IQ/OQ per ISO 13485:2016 section 7.5.6 Process validation ISO 13485:2016 - Medical Device Quality Management Systems 7
B VDA 6.3 Qualification as Process Auditor training course and exam VDA Standards - Germany's Automotive Standards 0
K Is Mold qualification / process validation always required? Manufacturing and Related Processes 7
J Simple supplier evaluation qualification process form that includes Risk Assessment Document Control Systems, Procedures, Forms and Templates 2
S Qualification Builds & Process Changes (AS9102 - First Article Inspection) AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 1
S Must I document qualification(s) or qualification process for Internal Auditors? IATF 16949 - Automotive Quality Systems Standard 10
P Approved Suppliers - ISO 13485 Normal Supplier Qualification Process Requirements ISO 13485:2016 - Medical Device Quality Management Systems 9
P Process or Performance Qualification Requirements Qualification and Validation (including 21 CFR Part 11) 5
R Process Qualification, Equipment Qualification, Operator Qualification - Sequence? Manufacturing and Related Processes 10
M Process Validation and Qualification of Legacy Equipment ISO 13485:2016 - Medical Device Quality Management Systems 10
R Line Leader Assessment form - Qualification process for production line leader Training - Internal, External, Online and Distance Learning 1
M Process Validation/Equipment Qualification - Class 1A (Sterile) Medical Device ISO 13485:2016 - Medical Device Quality Management Systems 12
S Operational Qualification for injection molding process Qualification and Validation (including 21 CFR Part 11) 2
M PQ and PPQ - Process Qualification for medical device manufacturing ISO 13485:2016 - Medical Device Quality Management Systems 1
S Example Flow Chart of Qualification of Process wanted APQP and PPAP 3
Y NPI (New Product Introduction) Process Qualification System Required Document Control Systems, Procedures, Forms and Templates 8
R Gage Tolerance vs. Process Parameter Tolerance - Process qualification Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
J Product/Process Qualification Plan Manufacturing and Related Processes 6
D Process Qualification - Heat Treatment Process Furnace - What is Thermal Mapping? Manufacturing and Related Processes 7
O Process Flow Diagram, DFMEA, PFMEA, Control Plan integrated softwares FMEA and Control Plans 3
C. Tejeda Process validation of rework assembly methods (medical devices) Medical Device and FDA Regulations and Standards News 2
L Looking for feedback on Nonconformity Process Flowmap ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 4
M Process Flow of ECN Product User and Service Guides Process Maps, Process Mapping and Turtle Diagrams 1
R Process Maps for ISO 17025 ISO 17025 related Discussions 2
L APQP Process Flow with CFT Roles and responsibilities APQP and PPAP 4
M Having Trouble Identifying KPI for Process ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
E Please help! ! I AM FRASTRATED SO MUCH! Should inactive ingredient be included in the unit formula if it is removed during the manufacturing process? US Food and Drug Administration (FDA) 0
I Supplier Evaluation Process ISO 13485:2016 - Medical Device Quality Management Systems 4
B A template for a injection molding process sheet with upper/lower- mean value tolerances Manufacturing and Related Processes 0
P ISO 9001: Quality Management as a process ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 14
R How many process maps are adequate for a company for IATF 16949? Process Maps, Process Mapping and Turtle Diagrams 17
Q Process matrix 9001:2015 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
Q Evaluate a process audit ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 24
J Best Practices for Choosing In-process Inspection Dimensions & SPC Dimensions Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
T FDA PMA review process - advisory panel timing? Other Medical Device and Orthopedic Related Topics 0
K Process FMEA responsible For "Make to Design Parts" (Inhouse or Suppliers ?) FMEA and Control Plans 3
M Passivation Process Manufacturing and Related Processes 2
G Mfr. Process Validation BEFORE Design Transfer? Other Medical Device and Orthopedic Related Topics 1
M Clinical evaluation interface with the risk management process EU Medical Device Regulations 9
D Integrated Management System (IMS) - Process Vs Clause Based Audits ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 19
D IATF NC Interaction of process diagram - Missing contingency plan Process Maps, Process Mapping and Turtle Diagrams 9
J Cleaning Process for Delicate Parts Manufacturing and Related Processes 4
E Audit Finding - Measurement of Process - Continuous Improvement - Trend Analysis Oil and Gas Industry Standards and Regulations 22
J ISO 10993-1:2018 Format to Perform Risk Management Process US Food and Drug Administration (FDA) 1
I Are suppliers required to hand over process validation reports? ISO 13485:2016 - Medical Device Quality Management Systems 20
S Process Monitoring using SPC software Quality Assurance and Compliance Software Tools and Solutions 6

Similar threads

Top Bottom