Sampling Plan for Final Inspection and Process Verification

V

vbhatta

#1
Hi,

I work in an electrical component manufacturing industry. We are working on a coil winding application where a coil is first wound and then glued to a LCP bobbin with an epoxy. We are supposed to run a pull test on the parts for coil to header adhesion to make sure that the parts build meet the customer spec. We normally grab a couple of coils being built in the assembly line and run pull-test on them. However, I was wondering if there is any statistically valid method that could be used to come up with a number of samples of parts that should be tested for pull-test?

Another scenario where we need to come up with a statistically valid sampling plan is during the final electrical/mechanical inspection of the parts built at the plant. We have traditionally been using a 32 piece sample data no matter what the production lot size is for a PO placed by the customer (PO for more than 32 parts, offcourse). However, we don't have any valid rationale behind the 32 pcs sample data. We have just been doing this for years and years until now.

There is no specific request from customer yet. But we are worried that the customer will someday ask us about the statistical rationale behind the 2 parts pull-test we have been carrying out (or the 32 parts final inspection plan) till now and we won't have any thing to present to the customer.

I found this paper in the internet (attached along with this post). But I am not sure if this would be applicable for our particular situation or not?? The sample sizes seem too big!

Any help will be greatly appreciated.

Thanks in advance.
 

Attachments

Elsmar Forum Sponsor
A

amit_rd

#2
Hello,

You may start by refering to ISO 2859 series and ISO 3534 series. It will give you a fairly good idea of sampling plan based on AQL/LQ.

Hope it helps.
 
V

vbhatta

#3
Hi Amit,

Thanks for your reply.

I am yet to do any detail reading on the ISO2859 standards. I will try to download the standards and will try to follow up on that. You mentioned that these standards are AQL based. I always thought that AQL plan is used for acceptance sampling? But the sampling plan that we are trying to come up with is not for "acceptance sampling". We are just trying to figure out how many components we have to test (for pull test or any other test that is done when the part is still in-process) so that we can make sure that the part meets the customer spec. I am sorry If I got it wrong. I am just beginning my journey in the field of sampling plan. :confused:
Thanks!
 

Statistical Steven

Statistician
Staff member
Super Moderator
#4
Hi Amit,

Thanks for your reply.

I am yet to do any detail reading on the ISO2859 standards. I will try to download the standards and will try to follow up on that. You mentioned that these standards are AQL based. I always thought that AQL plan is used for acceptance sampling? But the sampling plan that we are trying to come up with is not for "acceptance sampling". We are just trying to figure out how many components we have to test (for pull test or any other test that is done when the part is still in-process) so that we can make sure that the part meets the customer spec. I am sorry If I got it wrong. I am just beginning my journey in the field of sampling plan. :confused:
Thanks!
VBhatta

What you are doing is a form of acceptance testing. You are "accepting" the lot before shipping to customer. I would search for attrribute sampling and variable sampling plans.
 
M

Meplous

#7
Hello;
I'm new to this company, and I found out that they has been using an S3 AQL sampling plan for decades without any justification, I'm looking to change it to a LEvel II normal but still need a reasonable justification... please help.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#8
well the level II Normal is the 'industry standard' starting point...that is usually enough justification for 3rd party auditors. (not that it's a real justification, but it is commonly accepted as the standard)

Why do you want to change it? start your justification process there...

I would add that I am not a proponent of the Mil-Std/ANSI plans as the tables were a result of negtiations and not just statistics. (Lot size is usually irrelevent to the protection level). nor am I a fan of c=0 plans alone as they too don't give the best protection - they only give the appearance of protection, but some customers demand them.

I prefer to use my requirements for the acceptable defect rate (AQL) and the unnacceptable defect rate (RQL) and the 'confidence' I need for each based on the critical nature of the defect(s) to create my sample plan. I use the spreadsheet referenced above to do the calculaltions...
 
S

silentrunning

#9
We use ANSI/ASQC Z1.4-1993 General Inspection Level I for our commercial customers and General Inspection Level II for our Aerospace and Medical customers. I use our reject rate (both in house and customer) for the last 3 years as our justification for this.
 
M

Meplous

#10
Sorry I came to the request without a reason first. This is a secondary packaging line using an S3. We take samples 3 times a shift base on an s3 AQL. 50 samples x three time per shift (beg, mid, end).
This is not a continuous process, each lot runs for 4 to 6 shifts, which means from 600 to 900 to be inspected per lot.
This is a secondary packaging line each time an AQL is performed all the packaging components are destroyed and the product reprocess (repacked).
I have one packaging line runing on S3 and another for a news product starting on an Level II Normal AQL.
I'm looking for consistency.
 
Thread starter Similar threads Forum Replies Date
Q SMT Final Inspection Sampling Plan for boards off an SMT line Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
V Can give me the sampling plan for Receiving and Final inspection - AS9100? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
S Which Sampling Plan(s) Should I Use? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7
L Sampling Plan Risks AQL - Acceptable Quality Level 6
A Sampling plan for in-process QC (medical devices) Inspection, Prints (Drawings), Testing, Sampling and Related Topics 13
W LTPD, AQL, Ppk and Cpk validation sampling plan table Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
E Change in control plan - Do I have to do sampling? IATF 16949 - Automotive Quality Systems Standard 1
S Is using ANSI/ASQ Z1.4-2008 the correct sampling plan to determine Pass/Fail of Apparel measurements? AQL - Acceptable Quality Level 4
N Sampling Plan for Internal Audits - ISO 2859 or 3951 - Or Neither? Internal Auditing 6
R Reduced sampling plan for sterial products APQP and PPAP 0
T Defining sampling plan for different AQL AQL - Acceptable Quality Level 3
B AS9100D Sampling Plan AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 2
Nicole Desouza Sampling plan for a customer who wants AQL 1.0 (per ANSI Z1.4) AQL - Acceptable Quality Level 5
M Sampling Plan for Alumin High Pressure Die Castings Manufacturing and Related Processes 0
E Sampling plan for orthopedic implant - Process Validation Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
S How to make a Sampling Plan - Conveyor belts Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
S Help develop sampling plan for prototype samples (medical devices) Statistical Analysis Tools, Techniques and SPC 7
M Zero Defect Sampling Plan Standards Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
L ISO 2859-2 LQL sampling plan linked to %confidence/%reliability Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
K Sampling Plan for transparent tubular plastic parts from 32 different cavities Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
A AQL Sampling Plan SOP / WI - Medical Device Industry Inspection, Prints (Drawings), Testing, Sampling and Related Topics 14
J Sampling Plan Questions from the CQE Practice Exam Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
M Sampling Plan for for Chemical Analysis Testing of Medical Devices EU Medical Device Regulations 3
V Sampling Plan for Destructive Testing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
J Can ANSI Z1.4 sampling plan be used for sampling alone without the Acc/Rej criteria? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
C Sampling plan for destructive tests on small lots ISO 13485:2016 - Medical Device Quality Management Systems 20
B Designing a Sampling Plan - AQL AQL - Acceptable Quality Level 19
N Use of arrows in ISO 2859-1 Table 1 and 2-A sampling plan Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
S AS9100 Sampling Plan Requirements - 8.2.4 AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
S Military Sampling Plan 105E vs. ISO 2859-1 AQL - Acceptable Quality Level 2
kedarg6500 Acceptance Sampling Plan for Variables - Product Performance Testing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
M Manufacturing Process Validation Destructive Testing Sampling Plan Advice Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
S Where could I get reference to an OQA Sampling Plan of 1 per 1000 ? Quality Manager and Management Related Issues 4
R What to Report when Using C=0 Sampling Plan Supplier Quality Assurance and other Supplier Issues 15
R Results: Monte Carlo Simulation of Acceptance Sampling Plan AQL - Acceptable Quality Level 3
G Sampling Plan according to SAE ARP9013 C=0 Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
G Sampling Plan for Inspection of Metal Parts after CNC Machining Inspection, Prints (Drawings), Testing, Sampling and Related Topics 34
S Class III Sampling Plan - Explain AQL vs. 95%C & 90%R Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
G Sampling Plan for a Performance Qualification of an Inflation System Qualification and Validation (including 21 CFR Part 11) 2
S How to establish a Sampling Plan from the Rework percentage? AQL - Acceptable Quality Level 6
Q Sampling Plan for Paper and Tape Industry Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7
C Medical Device Tracking Sampling Plan using MIL-STD-105E Other US Medical Device Regulations 4
P Lot Acceptance Plan that specifies BS 6001 Double Sampling Plans, general inspection Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
A Destructive Testing Failure Mode Sampling Plan Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
B Best Attribute Data Sampling Plan - Early Production Containment Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
B In-Process Sampling Plan for a Secondary Package Adjustment Process Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
Proud Liberal Making a simple Sampling Plan by Variables Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
E How to determine the Lot Size for the OQ Sampling Plan Inspection, Prints (Drawings), Testing, Sampling and Related Topics 11
L Electrical Cable Harness Quality Control - Sampling Plan for Pull Test Manufacturing and Related Processes 4
G Sampling Plan - Sample Size Justification for a Bottling Cleaning Process Validation Qualification and Validation (including 21 CFR Part 11) 2

Similar threads

Top Bottom