Measuring Diameters in Coordinate Measuring Machine (CMM)

H

haripachan

#1
Hello,

Which is the better method of measuring diameter in coordinate measuring machine & reporting min/max values? (for diameter greater than 1m)

1---Measuring the feature as circle.& .finding the min/max value from circularity error.

2---Measuring points.&. finding the min/max values by simply adding diametrical opposite points?i.e, 0degree+90degrees, 45degrees+225degrees..etc

Please guide me....


 
Elsmar Forum Sponsor
T

True Position

#2
Re: Measuring diameters in Coordinate Measuring Machine

Hello,

Which is the better method of measuring diameter in coordinate measuring machine & reporting min/max values? (for diameter greater than 1m)

1---Measuring the feature as circle.& .finding the min/max value from circularity error.

2---Measuring points.&. finding the min/max values by simply adding diametrical opposite points?i.e, 0degree+90degrees, 45degrees+225degrees..etc

Please guide me....

Most CMM software has options to output both the normal Least Square results and the two functional fit type calcuations. Your #2 option is definitely questionable and is the reason micrometers will measure odd number lobed parts incorrectly. Your #1 option is better if you are not familiar with changing the evaluation settings.

What CMM software are you running? If you're running Calypso I'm more helpful.
 
H

haripachan

#3
Re: Measuring diameters in Coordinate Measuring Machine

Thanks for your reply....

I am LK Studio.....

User is asking for the diameter measured in the option 2...I am not sure whether this is right...Since we havent done it for any job.We usually measure circle, find its least square diameter and accordingly give the min/max based on circularity. Kindly help me whether the option 2 holds good for measuring diameter greater than 1.5m.
Also note that the number of points we are using to measuring diameter is 8 in both the cases...Whether there is any standard that mentions to take points more than 8 depending on size being measured...

Kindly help
 
T

True Position

#5
Re: Measuring diameters in Coordinate Measuring Machine

Your #2 option is definitely incorrect if you are concerned about diameters being out of round. You will rarely see the form error using 2 points, especially on parts with an odd number of lobes.

For now I would keep using your Least Squares then add/subtract form error method if you do not wish to change the evaluation settings.

As to number of points, I have not ever heard of a standard suggesting number of points to measure. When I used a touch trigger type machine I believe I used around 12 points per circle but I think it's a matter of preference.
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#7
I either report highest and lowest diameter - handy for correct SPC if precision machining - or average diameter with roundness. Reporting one diameter - whether with CMM or hand gages - is only meaningful when roundness is always less than 5% of the tolerance. Reporting two seems to show an interest in the roundness, so I would not recommend that approach at all.

The studies I have performed on a computer controlled CMM showed that 8 points is typically a good number, and over 10 points generally shows little significant improvement on a turned diameter. This may be different for manual CMMs.
 
H

haripachan

#8
So shall I adhere to option 1? Measuring circle and reporting the min/max diameter from Least square fit diameter +/- circularity error??
 

Stijloor

Staff member
Super Moderator
#9
Re: Measuring diameters in Coordinate Measuring Machine

Most CMM software has options to output both the normal Least Square results and the two functional fit type calcuations. Your #2 option is definitely questionable and is the reason micrometers will measure odd number lobed parts incorrectly. Your #1 option is better if you are not familiar with changing the evaluation settings.

What CMM software are you running? If you're running Calypso I'm more helpful.
I am not a CMM expert, but how about reporting the diameter of the Actual Mating Envelope (AME)? Re:ASME Y14.5–2009.

Stijloor.
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#10
Re: Measuring diameters in Coordinate Measuring Machine

I am not a CMM expert, but how about reporting the diameter of the Actual Mating Envelope (AME)? Re:ASME Y14.5–2009.
That would be appropriate if it was a fit function and - even more so - if it was called out as true position at MMC. Very practical for cylindrical features, too - but may not be necessary for a circular feature. Good point, though - 10 points are good for a circular feature, but cylindrical feature need to be checked at least 3 separate circular sections - for a total of 30 points as rule of thumb - to capture taper, skew, etc.
 
Thread starter Similar threads Forum Replies Date
R Inspection of Diameters on a CMM (Coordinate Measuring Machine) Inspection, Prints (Drawings), Testing, Sampling and Related Topics 13
M Measuring FIM (TIR) - Two inside diameters - Conflicting readings between inspectors Manufacturing and Related Processes 1
L Inspection Equipment Accuracy - Measuring the diameters of small holes Measurement Uncertainty (MU) 5
R Tools used for measuring (New to metrology) General Measurement Device and Calibration Topics 9
G Best way to calc uncert for measuring microscope without duplicating repeatability? Measurement Uncertainty (MU) 2
J Calibration cycle for monitoring & measuring tools used in medical device manufacturing General Measurement Device and Calibration Topics 5
cnbrosa Study Type 1 on a CMM using a measuring support Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
M Determining a tolerance value for Measuring devices in-house inspection General Measurement Device and Calibration Topics 12
D Accurately measuring Full Thread Length Inspection, Prints (Drawings), Testing, Sampling and Related Topics 11
R ULM Measuring Pressures General Measurement Device and Calibration Topics 1
M Missing measuring equipment General Measurement Device and Calibration Topics 6
Marco Bernardi MMC & LMC modifiers and CMM measuring techniques like diameter least squares and circularity or minimum/ maximum diameter Calibration and Metrology Software and Hardware 5
K Measuring Function MEDDEV 2.1/5 relation with MDD 93/42/EEC CE Marking (Conformité Européene) / CB Scheme 1
ScottK Measuring thread flank angle on a screw Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
D ASTM C1064 Temperature Measuring Device General Measurement Device and Calibration Topics 2
B Measuring and monitoring equipment - Understanding which procedures to be compliant with ISO 13485 ISO 13485:2016 - Medical Device Quality Management Systems 6
C ISO 9001:2015 Monitoring and measuring resources. Application a service industry ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 7
V Ammeter calibration - Measuring head (on pic.) problem General Measurement Device and Calibration Topics 1
D Monitoring and measuring resources - Example of how section ISO 9001 7.1.5 would apply to a manufacture of software ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 4
A CE mark - Measuring Instruments Directive confusion! CE Marking (Conformité Européene) / CB Scheme 0
M Measuring Capability of Process with Multiple Specifications Capability, Accuracy and Stability - Processes, Machines, etc. 6
E ISO 13485 7.6 Control of monitoring and measuring equipment - Assess the Validity ISO 13485:2016 - Medical Device Quality Management Systems 4
D Measuring fine tubing (< 0.100") "Wall by weight" General Measurement Device and Calibration Topics 11
G Posting Measuring Equipment Accuracy for User Information General Measurement Device and Calibration Topics 4
S ISO 9001 7.1.5.2 - Actions Taken When Measuring Equipment is Found to be Unfit for Use General Measurement Device and Calibration Topics 13
G ISO 9001 and ISO 17025 - Measuring tools not in calibration system General Measurement Device and Calibration Topics 3
S Calibration - Isolated current meter - Measuring patient auxiliary leakage current Calibration and Metrology Software and Hardware 4
G Measuring customer parts on a CMM - How many decimals to report to the customer? ISO 17025 related Discussions 28
qualprod Complying with ISO 9001:2015 - 9.1.1 b - Monitoring, measuring, analyzing and evaluation ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
Tagin Measuring supplier quality with small quantities Statistical Analysis Tools, Techniques and SPC 10
G Uncertainty of staging a short line scale standard on longer measuring machine? Measurement Uncertainty (MU) 4
U Measuring a Golf Club Face/Grip/Shaft Rotation General Measurement Device and Calibration Topics 7
Q Acceptable calibration accuracy of a 60" linear measuring device General Measurement Device and Calibration Topics 16
H Measuring Design Process Design and Development of Products and Processes 4
C AS9100D 7.1.5.2 / Calibration of Employee Owned Measuring Equipment AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
M Effectiveness Measuring and Efficiency Measuring In ISO 9001:2015 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
johnny johnson New measuring equipment selection (Cg/Cgk) Capability, Accuracy and Stability - Processes, Machines, etc. 2
S Cleanrooms - Particle Measuring - ISO 14644 Other Medical Device and Orthopedic Related Topics 3
S IOQ protocol for a Micro-Vu measuring system - Is a PQ required? Qualification and Validation (including 21 CFR Part 11) 2
K ISO 13485:2016 Cl. 4.2.3 - Determine QMS Processes, Monitoring, Measuring, etc. ISO 13485:2016 - Medical Device Quality Management Systems 4
L Radius Measuring Tools General Measurement Device and Calibration Topics 4
Proud Liberal Measuring axial and radial surface finish (16 Rz) on a broached internal radius Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
J IATF 16949 Cl. 7.1.5.2.1 - Gauges (Measuring Jigs) Calibration/Verification Records IATF 16949 - Automotive Quality Systems Standard 6
Claes Gefvenberg Worst measuring equipment ever? Coffee Break and Water Cooler Discussions 6
J Measuring an Untrue Radius - Metal Stamped and Formed Parts Inspection, Prints (Drawings), Testing, Sampling and Related Topics 8
A Calibration Interval - AS9100 - Control of Monitoring and Measuring Equipment Calibration Frequency (Interval) 8
P Tool for Measuring - Do I have to do more than one Gage R&R for the PPAP? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
R Auditing Fitness of Purpose for Monitoring and Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
J Measuring Leakage Currents with IEC 60601 defined Measurement Device (MD) IEC 60601 - Medical Electrical Equipment Safety Standards Series 15
rob73 Advice/recommendations for equipment to measure a soft pvc tube - Optical Measuring? General Measurement Device and Calibration Topics 4

Similar threads

Top Bottom