Minumim number of parts to conduct the Process Capability Study

E

Eduardo - 2003

#1
Is there a minumim of part to conduct the Process capability studies? I did 50 pieces, is this acceptables?:vfunny:
 
Elsmar Forum Sponsor
A

Al Dyer

#4
For what it's worth, my background is automotive. At the very least I would follow their guidelines and on a personal level would accept nothing less than 20 samples of 5 each. And that is just the start.

Capability needs to monitored over a time period, not just a sample size!
 

Howard Atkins

Forum Administrator
Staff member
Admin
#5
Originally posted by Al Dyer
For what it's worth, my background is automotive. At the very least I would follow their guidelines and on a personal level would accept nothing less than 20 samples of 5 each. And that is just the start.

Capability needs to monitored over a time period, not just a sample size!
This is the definition from the PPAP handbook......... but by my experience the customers ask for different amounts.
There is a difference between PPK for an initial run and CPK for a run over time.
What the customers are usually looking for is the width of the distribution. I have a number of experiences where the Std deviation is very low, but not centered and customers have changed tolerarances to give a good C/P PK.
There is a tendcy to sprinkle drawings with critical characteristics which are not really justified. The French have a system of ranking CC's from 1 to 4 and there can be 20 plus on a drawing.
The best way is to ask the customer what he wants in the PPAP, then there are no unpleasant surprises.
 
A

A. Stuart Dyer

#6
Agreed Howard,

Even within the big 3 there are variations on what they want, and we give them what they want. But when it comes to rubbing your back against the tree there are certain numbers of samples and group sizes that are required and as long as the warrant is signed and there is evidence that you will improve on the process, there will be no problem.

To anybody, just think that because a B3 engineer sais he wants this or that, that an auditor will not disagree and issue a finding. Sometimes, even when you have it in writing it does not mean the auditor can't site a nonconformance.
 
D

D.Scott

#7
A Stuart

To anybody, just think that because a B3 engineer sais he wants this or that, that an auditor will not disagree and issue a finding. Sometimes, even when you have it in writing it does not mean the auditor can't site a nonconformance.
While there is probably a bit of truth in what you say, the fact still remains - The requirements of the customer always overshadow the requirements of QS-9000. If the customer has asked for something in writing, the auditor should not be arguing or writing a nonconformance. Regardless what his personal feelings, he should move on to the next point.

Dave
 
R

remsqa

#8
Sample Size

Hai


The better person is the customer.

But the process capability study is done for better result and better understanding of the process ablity and performance for continous improvement .

So i rembember for better understanding the histrogram should have minimum 13 to 25 average values ,with 10 to 15 clause intervales .

So it is sugested to go for the sample sizs of 25*5 ie 125 components with 25 Sub groups.Any improvements pl reply

REGARDS

R.L.SATTHISH KUMAR
 

Steve Prevette

Deming Disciple
Staff member
Super Moderator
#9
The 25 sets of 5 (or 4) is a "correct" answer, but not for the reasons given. It is not related to a histogram, but to a control chart. Dr. Shewhart originally gave the suggestion that do not declare a process stable until you have 25 stable points from subsamples of 4 on a control chart. And process capability is meaningless unless the process is indeed stable.
 
Q

qualitygoddess - 2010

#10
It's all in the control chart

Steve Prevette said:
The 25 sets of 5 (or 4) is a "correct" answer, but not for the reasons given. It is not related to a histogram, but to a control chart. Dr. Shewhart originally gave the suggestion that do not declare a process stable until you have 25 stable points from subsamples of 4 on a control chart. And process capability is meaningless unless the process is indeed stable.
Steve makes a critical point. Before conducting a cap study, you have to know that the process is stable/in control. I advocate the creation of a control chart for the measured variable. Follow the basic rules for creating one of these (see Steve's post), and then you can calc process cap.
 
Thread starter Similar threads Forum Replies Date
D Determining the the maximum number of reprocessing cycles of attachments CE Marking (Conformité Européene) / CB Scheme 2
K Why 'FD&C act section number' and 'section number' in the title of the act are different? US Food and Drug Administration (FDA) 1
A Risk Number for each software requirement IEC 62304 - Medical Device Software Life Cycle Processes 7
K Adding the Notified Body Number CE Marking (Conformité Européene) / CB Scheme 2
C Quantifying risk in choosing the number of parts, operators and replicates in a GR&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
Jane's Like-for-like critical raw material change qualification - type of testing/ number of lots required ISO 13485:2016 - Medical Device Quality Management Systems 4
Q LOT or Serial Number Symbol not used when the information is contained in the UDI? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
Proud Liberal Power Query to combine multiple tables of unequal number of columns Statistical Analysis Tools, Techniques and SPC 1
Q How is Medical Device Number (MDL) assigned to companies? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 0
D How to get EUDAMED Single Registration Number (SRN) EU Medical Device Regulations 10
M Informational US FDA – Modifications to the List of Recognized Standards, Recognition List Number: 052 Medical Device and FDA Regulations and Standards News 0
M Nonconformity for missing form number on the job description document Nonconformance and Corrective Action 1
I Number of decimals in equation calculated by MiniTab Using Minitab Software 0
F 2017/745 Article 31 Single Registration Number Medical Device and FDA Regulations and Standards News 5
Z Do we still have to put UDI if we have DI and lot number seperately on our product ? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 4
Z Two Payment Identification Number (PIN) for the same order in DFUF website 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
Ed Panek GTIN (Global Trade Item Number) for non CE Mark Other Medical Device Related Standards 4
A The latest revision number and changes in automotive core tools IATF 16949 - Automotive Quality Systems Standard 1
G Belgium - How do I get an enterprise CBE Number Other Medical Device Regulations World-Wide 0
M Document Control - Revision Number in Document Names Document Control Systems, Procedures, Forms and Templates 4
M Informational USFDA – FDA Modernization Act of 1997: Modifications to the List of Recognized Standards, Recognition List Number: 051 Medical Device and FDA Regulations and Standards News 0
S How to number and control translated SOPs - Three languages Document Control Systems, Procedures, Forms and Templates 4
qualprod Calculate number of people in processes, considering cycle time/takt time = quantity of people Lean in Manufacturing and Service Industries 9
A Doubt on multiple inspection carrying out for same balloon number during Stage Inspection and Final Inspection? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
K Relabeling or Not Relabeling - Adding our internal Part Number barcode label 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
lilybef Number of lots required for stability testing of a Class II device in the 510(k) Qualification and Validation (including 21 CFR Part 11) 3
J DoE - Number of runs in Plackett-Burman (Minitab) Using Minitab Software 2
G Heat Number on CofC - Stainless steel tube Manufacturing and Related Processes 2
M Determining number of employees within the "Scope" of the QMS ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 9
qualprod What tier number fits in a company producing paper labels stuck on automotive parts? IATF 16949 - Automotive Quality Systems Standard 7
M Medical Device News TGA Consultation: Changes to a number of definitions and the scope of the medical device regulatory framework in Australia Medical Device and FDA Regulations and Standards News 0
J Question on very low NDC number with tolerable GRR ratio's Capability, Accuracy and Stability - Processes, Machines, etc. 7
S Is Lot Number required in addition to UDI serial number? Other Medical Device Regulations World-Wide 7
T Change control and configuration management - When to create a new model/part number? Other Medical Device and Orthopedic Related Topics 0
D IMDS for machining - Can my customer request a IMDS number for a part? APQP and PPAP 2
shimonv GTIN Number on the Packaging of a Serviced Medical Device EU Medical Device Regulations 0
W Is the RPN (risk priority number) in the PFMEA really a RPN without the detectability ISO 14971 - Medical Device Risk Management 4
M How to count the number of employees? Other Medical Device and Orthopedic Related Topics 4
bobdoering "nds" or Number of Discriminate Samples - the Necessary Tool to Work With "ndc"! Imported Legacy Blogs 0
H FDA product code and regulation number Other US Medical Device Regulations 3
P FDA's DRLM (Device Registration & Listing Module) Listing Number Question 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 9
Sidney Vianna High number of certificate suspensions in the IAQG OASIS database AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 14
J GLP Animal Study - Change number of treatment sites Other US Medical Device Regulations 2
S My department inherited a large number CAPAs ISO 13485:2016 - Medical Device Quality Management Systems 4
R Remote Support - Calculating Number of Employees IATF 16949 - Automotive Quality Systems Standard 2
I Number of HEPA filter in a room US Food and Drug Administration (FDA) 3
Mikey324 GR&R - Little to no part to part variation in single part number Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 14
M AS9100 Rev. D Transition Audit - Number of Audit Days AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
D Number of Audit Days - AS9100D Transition for a Small Shop AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 3
Q Change revision number in document when only codification was changed Document Control Systems, Procedures, Forms and Templates 8

Similar threads

Top Bottom