Is conducting of all MSA studies required, even if not required by the customer?

[tienie]

Re: Is conducting of all MSA studies required, even if not required by customer?

Hai

I'm interested in Amine.arafa reply on conducting MSA (linearity, bias, stability) based on calibration certificate. could you please explain more on this? if possible could you give any one example on this?

Now we only practising GR&R as Amit does.

Thank you in advanced
Tienie

 

[bobdoering]

Re: Is conducting of all MSA studies required, even if not required by customer?

Usually the "other techniques' are reserved for physical phenomena - which have significant repeatability issues - such as tensile testing, compression testing, etc.

 

[bobdoering]

Re: Is conducting of all MSA studies required, even if not required by customer?

1) Is it required to conduct MSA studies for measurement technique such as 'Micrometer' for every unit, as appraisers are different?

For Gage R&R (since MSA is actually ALL of the gage testing, NOT just gage R&R):

No - pick the appraiser with the best skill, the appraiser with the least skill (e.g. new appraiser) and another appraiser of typical skills. If you pass that, it shows that the gage is the correct gage for your job, no matter what skill level operator uses it. Done.

2) Is it required to conduct MSA studies for every Inspection fixture / template (Used for inspecting different products)?

First, remember there is a special technique for attribute gages. Your templates are typically attribute, and will need that technique (and more parts)

Second, if the fixtures are significantly different, they should be included to determine if they even work correctly. You really have no evidence otherwise that they do.

 

[bobdoering]

Re: Is conducting of all MSA studies required, even if not required by customer?

I'm interested in Amine.arafa reply on conducting MSA (linearity, bias, stability) based on calibration certificate. could you please explain more on this? if possible could you give any one example on this?

If you are sending your equipment out for calibration, the time-function portion of MSA (calibration, linearity, bias, stability) that indicates your gage still reads correctly should be accomplished by that.

On the other hand, gage R&R is done by internal operators, and it answers the question "is this the right gage for the job?" If you have not done it for the age, you can not answer the question accurately.

Now we only practising GR&R as Amit does.

That is never a good idea.

 

[Amine.arafa]

Re: Is conducting of all MSA studies required, even if not required by customer?

Hai

I'm interested in Amine.arafa reply on conducting MSA (linearity, bias, stability) based on calibration certificate. could you please explain more on this? if possible could you give any one example on this?

Now we only practising GR&R as Amit does.

Thank you in advanced
Tienie

Hi Tienie
For more details, BIAS is a calculation based on multiple measurements for one "true value" wich is the technique used by calibration labs to determine an average difference (BIAS) in a single measurement point, LINEARITY gives you the behavior of your instrument over the entire measurement range (As for example, the BIAS of a Voltmeter for 1V, 10V and 100V), and the STABILITY gives you the BIAS over time (You can obtain it by comparing BIAS in different certificates for the same measurement tool)
Hope this helped
Best regards
Amine

 

[bobdoering]

Re: Is conducting of all MSA studies required, even if not required by customer?

For more details, BIAS is a calculation based on multiple measurements for one "true value" which is the technique used by calibration labs to determine an average difference (BIAS) in a single measurement point,

The "true value" for most countries is a standard traceable back to that country's national standards (e.g. NIST for the US)

LINEARITY gives you the behavior of your instrument over the entire measurement range

A big, but not only reason this is done is because a gages used over a small portion of its measurement range may show wear in that range first.

STABILITY gives you the BIAS over time (You can obtain it by comparing BIAS in different certificates for the same measurement tool)

Needs to also track any changes made - if any - from adjustments during calibration over time.

 

[mwohlg]

Re: Is conducting of all MSA studies required, even if not required by customer?

Miner had a series of blog posts here on the Cove, that did a very good job of explaining the differences between Bias, Linearity, etc. I just found them earlier today but can't find them again now. Maybe someone who knows what they're doing can post a link to those?

 

[Jim Wynne]

Re: Is conducting of all MSA studies required, even if not required by customer?

Miner had a series of blog posts here on the Cove, that did a very good job of explaining the differences between Bias, Linearity, etc. I just found them earlier today but can't find them again now. Maybe someone who knows what they're doing can post a link to those?

Miner's MSA Blog is here.

 

[antonjav]

Re: Is conducting of all MSA studies required, even if not required by customer?

Hi Amit, just to clarify, you do not have to perform GRR, linearity, bias, and stability for each measuring device. The requirement is to perform statistical study for each measurement device type provided that the same is referenced in the control plan. Hence, this means that if you have 10 calibrated calipers, you could just get one and then determine if GRR, linearity, bias, and stability (unfortunately all of it for this one) would be appropriate to determine the amount of variation present -- provided that this caliper is identified or referenced in the control plan.

Of course, if you do GRR, you could easily identify the kappa values (or p values if linearity) and see if the measuring devices are fit for use or if some adjustment has to be made to enahnce accuracy or precision. Hope that this helps.

 

[Marc]

Re: Is conducting of all MSA studies required, even if not required by customer?

Note that sometimes a company has a number of measurement device types, but in specific gauge types they may not be from the same manufacturer, and there may be age differences between the individual devices. Just a few thoughts to consider.