- 97 Views
- Uploaded on
- Presentation posted in: General

Slide #2 – Zooming Presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Using this presentation:

- Slide #2 – Zooming Presentation
- Slide #2 contains an embedded zooming slideshow – 3 things to make it work
- 1) You’ll need an internet connection
- 2) You’ll need Flash for Internet Explorer – usually installed by default
- 3) And: You may get a security warning about using active content, in which case “Enable Content”
- The zooming slideshow will only play when PowerPoint is in “Slide Show Mode”
- Click this button – bottom right corner - to get Slide Show Mode, and wait for the content to load
- Slide #2 – YouTube Video
- Slide #3 contains an linked YouTube Video – To play this you need an internet connection, and you’ll need to go to Slide Show Mode, wait for the movie to load (may take some time) and then click on the movie to play it.
- NOTE: If you cannot connect to the internet through PowerPoint go directly to these links in your web browser:
- Zooming Presentation Available Here:
- http://prezi.com/-sxorzwzdzp8/what-is-measurement-system-analysis/

- “What is Measurement System Analysis?” Full Video Available Here:
- http://youtu.be/eXHKi6Osb6s

- Slide #4 Onwards
- 20 Slides you can use for your own purposes

Video Link - What is Measurement System Analysis?

What is Measurement System Analysis?

Q: What is Measurement System Analysis (MSA)?

A: It’s a set of techniques that allow us to answer the question:

IF I USE THIS GAGE TO MEASURE,

HOW MUCH CAN I TRUST THE MEASUREMENTS I GET?

MSA is based on Measurement Error

Understanding Measurement Error

Take a single item, and measure it multiple times using the same gage/same technique/same appraiser

Understanding Measurement Error

Record the measurements and draw a histogram

Understanding Measurement Error

The histogram represents a sample from a normal distribution with a Mean, and a Standard Deviation (derived from spread)

Understanding Measurement Error

- Consider the position of the mean – This is how we determine the bias of the system
- Imagine we had measured a reference size – a standard – of a known dimension.
- We could compare the mean of our results to the actual size of the standard.
- The difference is Bias

Bias

Reference Value = 0.500 – This is a known size

Mean of multiple measurements = 0.525

The gage is, on average, measuring about 0.025 too big.

It has a positive bias of 0.025

Bias

The gage is, on average, measuring about 0.025 too small.

It has a negative bias of 0.025

Bias

The gage is, on average, measuring the same size as the standard.

It has a zero bias

Bias

But, we have only dealt with Bias at one size at one point in time

A Gage is used over a range of sizes

And over a period of time

Bias may change depending on these factors:

Linearity

Change in Bias over the operating range of the gage

Stability

Change in Bias over time

Bias

Linearity – Change in Bias over operating range

Bias

Stability – Change in Bias over time

Bias

Stability & Linearity

For standard Gages - How does the calibration system deal with Bias?

Variation

Repeatability & Reproducibility

- Bias is based on the location of the mean of the distribution
- What about the spread of sizes?
- For a perfect gage this spread would be as small as possible
- We need to determine if we can live with the spread (variation) of measurement error from the gage
- We know that when one person uses the gage we get variation – This is the variation inherent in the Gage – REPEATABILITY
- If we have more than one person using the gage, this may introduce more variation - REPRODUCIBILITY

Variation

Repeatability & Reproducibility

Variation

Gage R&R

One way to determine the amount of variation in the Measurement System is through a Gage R&R Study

Take say, 10 parts, 3 appraisers, and measure each part 3 times ( or 15 parts x 4 appraisers x 5 replicates – whatever you want)

Analyze the results using statistical methods e.g. Analysis of Variance (ANOVA) to determine how much variation comes from

Gage R&R

Repeatability

Reproducibility

Variation

Gage R&R

Screenshot from Free Online Gage R&R ANOVA Calculator at www.GageRandR.com

Variation

Gage R&R

Variation

Gage R&R

When we’ve calculated the magnitude of the

Repeatability

Reproducibility

Both together – Gage R&R

We can compare them to:

A Tolerance

A Process Capability

The amount of Total variation in the Gage R&R Study

Anything else that helps answer the question:

How much can I trust my data if I use this Gage ?

- Visit:
- www.GageRandR.com
- For more info about:
- Measurement System Analysis
- Gage R&R
- Free Online Gage R&R Calculator (ANOVA)
- Interactive Process and Gage Simulation
- Other helpful stuff

dave@gagerandr.com