Zero part to part variation - Gage R&R project

[Eng.Hamad]

Hi,

I work on a gage R&R project. I and my partner used a digital caliper to measure bolt holes of two rotors (12 points) each point is measured three times. When I got the results, there is zero part to part variation! what does this mean? Also, the gage R&R %study variation is 100%.

Can I conclude that MS is not adequate?

The MS resolution is 0.01 inch
Accuracy is 0.01 inch

Thank you,

 

[optomist1]

part drawing, part dimension spec limits?

 

[Eng.Hamad]

Hi optomist1,
The rotor is ACDelco Silver 18A925A Front Disc Brake Rotor. I tried to find any drawings or specification limits, but I didn't find any. It seems to me that the best bolt size is M14-2. It is the bolt size that fits the cars that use this rotor.

I found a rotor that looks like the two I have. It shows bolt hole diameter 0.635 in

 

[Jim Wynne]

Hi,

I work on a gage R&R project. I and my partner used a digital caliper to measure bolt holes of two rotors (12 points) each point is measured three times. When I got the results, there is zero part to part variation! what does this mean? Also, the gage R&R %study variation is 100%.

Can I conclude that MS is not adequate?

The MS resolution is 0.01 inch
Accuracy is 0.01 inch

Thank you,

What does "measure bolt holes" mean? Size? Location? Please also explain the 12 points of measurement. What does the bolt size have to do with it?

 

[Eng.Hamad]

Hi Jim Wynne,
Sorry for confusing you.
The idea is to measure two rotor bolt holes (see attached). each rotor has 6 stud holes. I did not find any drawings or specifications except for product weight 19.3 pounds, and dimensions 12.33 x 12.33 x 3 inches. See excel file for gage R&R measurements.

 

[Jim Wynne]

Hi Jim Wynne,
Sorry for confusing you.
The idea is to measure two rotor bolt holes (see attached). each rotor has 6 stud holes. I did not find any drawings or specifications except for product weight 19.3 pounds, and dimensions 12.33 x 12.33 x 3 inches. See excel file for gage R&R measurements.

You didn't answer my questions.

 

[Eng.Hamad]

You didn't answer my questions.

Sorry. I just wanted to estimate the hole size using bolt size. I don't think it is required for gage R&R right?
Do I need to specify specification limits to get part-to-part variation?

Thank you,

 

[Bev D]

What are you atually trying to do? Do you work at the manufacturer of the rotor?
Why are you trying to estimate the hole size? That won’t help anything.

 

[Eng.Hamad]

What are you atually trying to do? Do you work at the manufacturer of the rotor?
Why are you trying to estimate the hole size? That won’t help anything.

I am a student, and I have a gage R&R project. I need to do it for any vehicle measurements using digital calipers. I chose rotors. I think estimating hole size helps to estimate the tolerance limits. I need tolerance limits in my project.

Thank you,

 

[Miner]

Brake rotors are precision machined on all dimensions. Digital calipers would be woefully inadequate to even begin to see the variation in the dimensions. This would be a resolution issue.