# Laser Micrometer Uncertainty - Calibrating Deltronic Pin Gages

#### Charles Wathen

##### Involved - Posts
Hi guys,
I have a question on a uncertainty calculation that I'm trying to determine.

I want to determine the uncertainty of a measurement using my Zygo Gold laser micrometer when we calibrate Deltronic Pin Gages. Here is the info:
Zygo laser micrometer resolution: .000001"
Zygo laser micrometer accuracy: .00002"
Zygo laser micrometer repeatability: .000005"
Pin Gage Standard XXX (used to cal laser mic): .00001"

By calculating the above, I get an expanded uncertainty of .000026".

My question is: should I be including the accuracy of the Deltronic Pin Gage I'm calibrating? It has a standard accuracy of +.00004 -0".

If I do, then my expanded uncertainty is .000053" which seems higher than I expected. If I do use this, should I subtract this value from the .00004" tolerance of the Deltronic Pin Gage to come up with an uncertainty of .000013"?

A

#### Al Dyer

My advice would be to drop the pin from the laser mike uncertainty calculation.

The laser is being reviewed, not the pin, and you should be able to use any size pin and get the same uncertainty.

Try a test with increasing sized pins and see if the linearity of the laser is stable

G

#### Graeme

Re: Uncertainty question

Charles Wathen said:
My question is: should I be including the accuracy of the Deltronic Pin Gage I'm calibrating?
The measurement uncertainty applies to the measuring system. A measuring system is independent of the items it measures.

The uncertainty is used to help determine if the object being calibrated (the pin gage) is within its own accuracy specification.

The ratio between the measurement uncertainty (of the measuring system) and the accuracy specification (of the object being calibrated) is an indicator of the ability of the system to make that particular measurement.

If the object being calibrated was included as part of the measurement system, then it would be reasonable to be required to perform an MSA for every workload item! (Impractical, outrageous and uneconomic, but weirdly reasonable. )

R

#### Ryan Wilde

Re: Uncertainty question

Charles Wathen said:

Hi guys,
I have a question on a uncertainty calculation that I'm trying to determine.

I want to determine the uncertainty of a measurement using my Zygo Gold laser micrometer when we calibrate Deltronic Pin Gages. Here is the info:
Zygo laser micrometer resolution: .000001"
Zygo laser micrometer accuracy: .00002"
Zygo laser micrometer repeatability: .000005"
Pin Gage Standard XXX (used to cal laser mic): .00001"

By calculating the above, I get an expanded uncertainty of .000026".
Using all rectangular distributions, I got about the same. (0.0000265")

My question is: should I be including the accuracy of the Deltronic Pin Gage I'm calibrating? It has a standard accuracy of +.00004 -0".
You wouldn't take into account the accuracy of the Deltronic Pin Gage, especially since that is what you are trying to determine. You would, however, need to incorporate the repeatability of measuring a deltronic gauge. Using your system, I would guess this to be around 0.000005" with a single standard deviation.

At this point, we have an uncertainty of about 0.000028".

What we are forgetting is the environmental effects. Temperature is the big wildcard on all dimensional measurements. If your laboratory is 68 ±5 °F (20 ± 2.8 °C), and you don't compensate for the thermal effects, you will have a very different uncertainty.

Thermal expansion of tool steel (such as a Deltronic Pin) is 6.4 µin/in/°F (11.5 µin/in/°C).

Therefore, if you are measuring a 0.5" pin at 72 °F (22.2 °C), and the pin is exactly 0.5" at standard temperature (68 °F/ 20 °C), you would actually measure [0.5" + (0.0000064" *0.5" *4 °F)], or 0.500013". With everything else in the system being perfect (which it isn't), you have an error of 0.000013" due to temperature alone.

I do not know the temperature effect on the Zygo laser, but thermal expansion of the pin, and thermal effects on the Zygo laser must be added to the uncertainty budget.

If I do, then my expanded uncertainty is .000053" which seems higher than I expected. If I do use this, should I subtract this value from the .00004" tolerance of the Deltronic Pin Gage to come up with an uncertainty of .000013"?
No, the tolerance of the Deltronic pin has no bearing on your measurement. The tolerance of the pin under test is entirely arbitrary to the uncertainty of measuring the pin.

Ryan

#### Charles Wathen

##### Involved - Posts

Laser Micrometer Suggestion (if any) for diameters that are +/-.0001 inch General Measurement Device and Calibration Topics 1
A question on Calibration on In-line Laser Micrometer General Measurement Device and Calibration Topics 1
D Laboratory where we can have parts checked for Thickness with a Laser Micrometer General Measurement Device and Calibration Topics 6
D Laser Micrometer for checking Thickness of Steel - Any Recommendations or Comments General Measurement Device and Calibration Topics 3
P How to Calibrate Laser Micrometer when no Calibration Company in the Country? General Measurement Device and Calibration Topics 3
M Choosing a Laser Micrometer - Your recommendations? General Measurement Device and Calibration Topics 8
Gage Resolution / Measurement Accuracy - Laser scan micrometer has a 6 digit display General Measurement Device and Calibration Topics 4
Is IQ necessary for laser marking validation? EU Medical Device Regulations 3
Biocompatibility Testing for Laser Epilation Device EU Medical Device Regulations 2
Cleaning Process after laser marking on orthopaedic implants Other Medical Device and Orthopedic Related Topics 3
Informational US FDA Laser guidances Medical Device and FDA Regulations and Standards News 2
Class IV Laser Regulations IEC 60601 - Medical Electrical Equipment Safety Standards Series 3
Requirements for hand-held laser welding equipment Other ISO and International Standards and European Regulations 0
Installation Qualification (IQ) and Operational Qualification (OQ) for Laser Marking 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 2
Medical Device Classification - Laser Guided Positioner EU Medical Device Regulations 2
Precise Laser Printer: Recommendation Manufacturing and Related Processes 2
Traceability of laser based x-y measuring machine General Measurement Device and Calibration Topics 5
Laser Etching Advice for Permanent Device Marking Manufacturing and Related Processes 5
A How to Calibrate Laser Beam Tester & Radiation Monitor General Measurement Device and Calibration Topics 3
Metrology Laser Reliability General Measurement Device and Calibration Topics 2
IEC 60825-1 Class 3R Laser Off-The-Shelf or Custom Label Needed Other ISO and International Standards and European Regulations 3
A Is IEC 80601-2-60 necessary for Dental Laser? IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
A Innovation in Laser Welding Manufacturing and Related Processes 2
Kanomax hand held Laser Particle Counter Calibration Calibration Frequency (Interval) 6
A Standards for Emergency Button for a Dental Laser IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
Laser Wavelength Traceability for Laser Interferometers General Measurement Device and Calibration Topics 4
Laser Precision Linear Measurement - Inherrent Accuracy of 10 -6 - Nice PDF Paper General Measurement Device and Calibration Topics 1
A Dental Laser Certification IEC 62304 for a Firmware IEC 62304 - Medical Device Software Life Cycle Processes 1
A Type of Materials to comply with IEC 60601 (Dental Laser Case) IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
White Light vs. Laser Scanner - Investing in a 3d Scanner Quality Tools, Improvement and Analysis 6
FDA releases Updated Laser Products Regulation Other US Medical Device Regulations 1
Laboratory Scope for a Laser Fabrication Shop IATF 16949 - Automotive Quality Systems Standard 2
Process FMEA for Welding and Laser Cutting FMEA and Control Plans 3
PPAP-PSW Accuracy Concern - Laser Cut Holes In Formed Fabricated Steel Part APQP and PPAP 15
E Laser Marking effects on the Fatigue Strength of Alloys CE Marking (Conformité Européene) / CB Scheme 6
IEC60825 - Laser Safety - Calculating Maximum Permissible Exposure Correctly Other ISO and International Standards and European Regulations 1
How to determine Failure Tolerance Time of Laser Equipment? IEC 60601 - Medical Electrical Equipment Safety Standards Series 27
H Laser Etching on Stainless Steel Knobs - Quality Issue Manufacturing and Related Processes 17
P 400 micron Difference between CMM Results and Laser Tracker Results General Measurement Device and Calibration Topics 7
D FMEA for Laser Cutting of Die Cast parts in AM60B Magnesium FMEA and Control Plans 1
Method to determine the Uncertainty of the readings of a Laser Scanner Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
B Laser Weld Strength - Laser Welding Medical Instruments Reliability Analysis - Predictions, Testing and Standards 8
Do FDA Laser Regulations Apply to Components? US Food and Drug Administration (FDA) 1
D How to do MSA on a Laser Mike, Rules, and Pressure Gage? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
Internal Calibration for Laser Temperature Gauges Manufacturing and Related Processes 3
A Substantial Equivalence for Laser Wavelength - Class 2 Aesthetic Product Various Other Specifications, Standards, and related Requirements 2
E Faro Laser Tracker Calibration Source Needed General Measurement Device and Calibration Topics 5
Reusable Soft Tissue Surgical Laser Fiber Sterilization Method US Food and Drug Administration (FDA) 3
E Blade Inspection - Does anyone use blade scaning software for a CMM or laser scanner? Design and Development of Products and Processes 3
Infrared Tachometer vs. Laser Non-Contact Tachometer vs. Stroboscope - Differences Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4