Receiving Inspection Plan of COTS and SCH Help

[Matt50]

Greetings All,

I am a quality inspector and test technician for a US navy prime contractor and I have been asked for input regarding how to increase the efficiency of our receiving inspection. After reading ISO 9001:2015, MIL-STDS, customer contracts and purchase orders, I am struggling to understand how my company has established some of its receiving inspection plans.

For example, we buy COTS and SCH such as nuts, bolts, adhesives, and wire ties from places like McMaster-Carr that are shipped with a Certificate of Conformance. When we receive them, we are required to do 100% dimensions on a sample every time. My question is, if the C of C states that what they sent complies with what we ordered and we ordered a ASME or ISO compliant bolt, shouldn’t that relieve us from having to do anything short of making sure the part number matches the purchase order?

 

[Tagin]

If you don't have any specific imposed requirement (e.g., by customer), then the extent of the inspection is a matter of risk assessment.

It is arguable that the CoC provides additional confidence (i.e., reduced risk) that the product is incorrect. But it is also arguable that two pieces of paper (CoC and packing slip) are not really any proof that the product was correctly picked and packaged than just one piece of paper. After all, CoCs are often just packing slips in a different format.

If you receive a wrong part (e.g., correct size nut but wrong thread), how will that impact production? Will it sit on the shelf for 6 months until it is discovered? Will it hold up a million dollar piece of equipment 2 weeks while you call McMaster to order replacement nuts? How often has McMaster sent incorrect parts in the past? Is it a trend? If the part has a 30-week leadtime, can you afford to not be sure its correct until it gets discovered in production?

In my view, you want to tailor your inspections to the risk. Part AA has always come correctly from McMaster so CoC suffices. Part BB from a sheetmetal shop has had 3 erroneous shipment in the last year, where edges were not deburred, and twice where a single drilled hole was mislocated. So, for part BB your inspection should check for those issues, and perhaps all dimensions.

 

[Jim Wynne]

I know that COTS is Commercial Off-the Shelf, but what is "SCH"? Please spell out abbreviations on first use in a post.

 

[Matt50]

If you don't have any specific imposed requirement (e.g., by customer), then the extent of the inspection is a matter of risk assessment.

It is arguable that the CoC provides additional confidence (i.e., reduced risk) that the product is incorrect. But it is also arguable that two pieces of paper (CoC and packing slip) are not really any proof that the product was correctly picked and packaged than just one piece of paper. After all, CoCs are often just packing slips in a different format.

If you receive a wrong part (e.g., correct size nut but wrong thread), how will that impact production? Will it sit on the shelf for 6 months until it is discovered? Will it hold up a million dollar piece of equipment 2 weeks while you call McMaster to order replacement nuts? How often has McMaster sent incorrect parts in the past? Is it a trend? If the part has a 30-week leadtime, can you afford to not be sure its correct until it gets discovered in production?

In my view, you want to tailor your inspections to the risk. Part AA has always come correctly from McMaster so CoC suffices. Part BB from a sheetmetal shop has had 3 erroneous shipment in the last year, where edges were not deburred, and twice where a single drilled hole was mislocated. So, for part BB your inspection should check for those issues, and perhaps all dimensions.

If you don't have any specific imposed requirement (e.g., by customer), then the extent of the inspection is a matter of risk assessment.

It is arguable that the CoC provides additional confidence (i.e., reduced risk) that the product is incorrect. But it is also arguable that two pieces of paper (CoC and packing slip) are not really any proof that the product was correctly picked and packaged than just one piece of paper. After all, CoCs are often just packing slips in a different format.

If you receive a wrong part (e.g., correct size nut but wrong thread), how will that impact production? Will it sit on the shelf for 6 months until it is discovered? Will it hold up a million dollar piece of equipment 2 weeks while you call McMaster to order replacement nuts? How often has McMaster sent incorrect parts in the past? Is it a trend? If the part has a 30-week leadtime, can you afford to not be sure its correct until it gets discovered in production?

In my view, you want to tailor your inspections to the risk. Part AA has always come correctly from McMaster so CoC suffices. Part BB from a sheetmetal shop has had 3 erroneous shipment in the last year, where edges were not deburred, and twice where a single drilled hole was mislocated. So, for part BB your inspection should check for those issues, and perhaps all dimensions.

Thanks Tagin, you gave me some good info and points to think about.

Tailoring the inspection to the risk is what I think I'm going to try to get management onboard with. Many, if not most of our inspection reports were drafted over 15 years ago and have never been updated. I read your reply at lunch today and did a quick search and haven't found a single NCR against a COTS item from several suppliers. Maybe I can get a compromise by doing a visual inspection on a small sample per lot and comparing them to a 100% tested good piece that we keep in the inspection room as a “standard”. We aren’t a high volume facility and usually have long lead times for the stuff we make, so if a box of bolts are wrong it would be an inconvenience, but it wouldn’t stop production.

I am also thinking that since most vendors include a cad drawing, perhaps we could add a PO clause that states the C of C needs to have a statement that says the part conforms to the drawing. I don’t know if that would add any benefit in terms of the vendor paying more attention when they pick the part. I also don’t know if a distributor like Mcmaster-Carr would include a copy of the certs from the manufacturer of the bolt, nut, washer. etc. and if they did, if that would have any benefit.

 

[Matt50]

I know that COTS is Commercial Off-the Shelf, but what is "SCH"? Please spell out abbreviations on first use in a post.

Hi Jim,

My company uses it for Standard Catalog Hardware. I don't know if it's a standard abbreviation.

 

[Jim Wynne]

Then it's the same as COTS?

 

[Matt50]

Then it's the same as COTS?

The company I work for uses SCH for parts that are built to a specific standard such as military standard (MS parts) and uses COTS for everything else. I am not sure of the rationale behind it, probably just an excuse to use more acronyms.

 

[Tata347]

Greetings All,

I am a quality inspector and test technician for a US navy prime contractor and I have been asked for input regarding how to increase the efficiency of our receiving inspection. After reading ISO 9001:2015, MIL-STDS, customer contracts and purchase orders, I am struggling to understand how my company has established some of its receiving inspection plans.

For example, we buy COTS and SCH such as nuts, bolts, adhesives, and wire ties from places like McMaster-Carr that are shipped with a Certificate of Conformance. When we receive them, we are required to do 100% dimensions on a sample every time. My question is, if the C of C states that what they sent complies with what we ordered and we ordered a ASME or ISO compliant bolt, shouldn’t that relieve us from having to do anything short of making sure the part number matches the purchase order?

No, I've had COTS parts come in incorrectly for many reasons, unless you've shown a justification you need to document an "inspection" however, One item to consider is that if you have sufficient data; then "reduce" the inspection plan (unless specified by customer); and keep reducing it until there is nothing left to do but a visual / C of C review. this way you can show that you monitored the inspections individually.. it may be a hard jump to go from a sample mechanical to only visual across the board.. we also changed across the board our COTS items to something minor - like 10 pieces for mechanicals & any failure would revert them to our standard inspection level (or tighter). These two things together increased our efficiency and throughput significantly, without sacrificing quality. include the risk justification as others have noted, if you reduce inspection levels on a part by part basis and ensure you have sufficient checks in the subsequent processes that would detect an error. If you reduce sampling by part number you will need to document your process.. see also ISO 2859-1 or consider doing a "skip lot" methodology for a designated number of lots then reduce the size.. here's some more information using the AQL inspectors ruler that may be helpful:
INFO - AQL Inspector's Rule

​

Tata

 

[Enghabashy]

No, I've had COTS parts come in incorrectly for many reasons, unless you've shown a justification you need to document an "inspection" however, One item to consider is that if you have sufficient data; then "reduce" the inspection plan (unless specified by customer); and keep reducing it until there is nothing left to do but a visual / C of C review. this way you can show that you monitored the inspections individually.. it may be a hard jump to go from a sample mechanical to only visual across the board.. we also changed across the board our COTS items to something minor - like 10 pieces for mechanicals & any failure would revert them to our standard inspection level (or tighter). These two things together increased our efficiency and throughput significantly, without sacrificing quality. include the risk justification as others have noted, if you reduce inspection levels on a part by part basis and ensure you have sufficient checks in the subsequent processes that would detect an error. If you reduce sampling by part number you will need to document your process.. see also ISO 2859-1 or consider doing a "skip lot" methodology for a designated number of lots then reduce the size.. here's some more information using the AQL inspectors ruler that may be helpful:
INFO - AQL Inspector's Rule

​

Tata

* the technical requirements , inspections & test in ASTM, ANSI/ BS; ISO regarding components & parts " i.e. : bolts ; nuts; threads,---etc – could be considered

**You can refer also to switch rules & lot by lot inspection plan referenced in ISO 2859 -1& 2

***the sampling plan schedules, the relevant AQL & batch/lot size,--etc-- are considered parameters for inspection & control plans