1. Air Gaging George Schuetz 2017
Technical Brief
Air Gaging
George Schuetz
2017

2. Air Gaging from Mahr Federal
Objectives
To understand why air gaging is a valuable Dimensional Measurement Solution
To learn about the Air Gaging products available
To learn some of the applications for Air Gaging
To learn some of the changes implemented at Mahr Federal to improve product line

3. Why Air Gaging? Air Gaging is a measuring system that
Allows for fast measurement
Self aligning
Provides high resolution
Performance to 0.1um/5u”
Easy to use
Little operator skill involved
Is non-contact
Won’t mar the part
Self-Cleaning
Air blows away surface contamination

4. When to use Air Gaging? Have a tight Tolerance condition
<± 40um / ± ”
Know when a part is good or bad
Know the variation from the nominal
Have a high volume of parts to measure
Measure quickly with min. operator influence
Or, have a geometric measurement –
maybe not of high volume but where alternative measurements (i.e. CMM’s) are too time consuming
Taper.Straightness/Center Distance
Environment is dirty

5. Is Air Gaging Difficult to Apply?
No – applying air gaging is often no different than selecting an adjustable bore gage, fixed mechanical plug gage, or a snap gage
You need to know the same information
Size
Tolerance
Where the measurement is to be made
What is the surface finish*
But watch out!

6. Principles of Air Gaging
Just like a garden hose – as the distance D gets smaller and restricts the water flow – pressure builds up in the hose. What can you say about the flow of the water as the distance is changed?
Water and air act very similar! D P

7. What’s Happening with Flow and Pressure+ +
Flow
Pressure
Distance
Distance +
Flow increases as the distance between the nozzle and restriction increases
Pressure increases as the distance between the nozzle and restriction decreases

8. Types of Air Gage Systems
Fixed Magnification – Single Master
Lower master costs
Faster to set up
Accuracy built into gage
Can use Master Restrictors to qualify system
Dirt and oil in air system can change calibration
Must match display and tooling
Adjustable Magnification – Two Masters
More master cost
Harder to set up
One amplifier can work with a variety of tooling
Can verify its own calibration
Can compensate for worn tooling or dirty system

9. Errors at extremes of tolerance Errors at center of tolerance
The type of air gage selected – determines where the error may be
Single Master System
Dual Master System
Errors at extremes of tolerance
Errors at center of tolerance

10. Universal Dimensionair
Fixed Magnification System
Easiest to use
True Analog Display
Single or Multiple display units – taper and diameter
Adjustable – two master system
Compatible with most competitive tooling

11. Column Gages 1840 Column 1841 Signal Sharing Column Single air input
Single / Dual Mastering
Full feature column – dynamics, outputs, classification, multi- color LCD
1841 Signal Sharing Column
Up to 4 air inputs
Single / Dual Mastering
Full feature column – signal sharing for math equations, dynamics, outputs, classification, multi-color LCD

12. uDimensionair Portable or bench mounted air gage display
Adds portability to air gaging
Interchangeable parts make it configurable for many applications
Uses standard Mahr Federal single master tooling
Magnifications 60, 50, 20
Operates like a uMaxum

13. Bench Amplifiers for Air
832
Fixed Magnification
Full feature amp
Single or Dual input
C1208
Full feature amp
Single or Dual mastering
Single input
PC programmable
C1245
Single or dual input
Single or dual mastering
Up to three separate display readings
Full feature with analog meter

14. What makes up an Air Plug?
Hardened Steel cylinder with air passages and opposed jets
Air passes through the probe then through the jets
Proximity of part to jet throttles air flow resulting in pressure changes
An air gage instrument measures pressure and displays part size

15. Why is Surface Finish Important?
What is the true size?

16. Types of Plugs Body Styles – Jet locations Thru hole – 12.5mm/0.5”
Blind – 4mm/0.156”
Super Blind 2.4mm/0.094”
Relieved/Non-relieved
Continuous body length
Stop Collars
Specific depth or short land

17. Types of Plugs
Two Jet
Most common for ID/OD, check for form errors – diameter variation, bell mouth, taper, barrel shape

18. Types of Plugs Three Jet Four Jet * Six Jet *
For checking diameter variation on parts with triangular form error
Used with standard 2-jet system
Four Jet *
For average diameter reading – requires four jet Dimensionair
Six Jet *
Average readings of three diameters – tends to find average diameter of two or three point out of round conditions
*Requires proper Air Display System

19. Measuring OD’s Air Rings are available in 2 or 3 jet configurations
Snaps are available in single or multiple circuit configurations

20. Air Gaging Applications
No other method can get so many measuring points in a such a small area

21. Process Improvements @ Mahr Federal New Material for Standard Plugs
Create two standard plug options
HCC (High Chrome Content Stainless Steel)
Chromed HCC
Benefits of the HCC line
Reduces manufacturing steps – shorter delivery
Reductions can be passed on to the customer – lower price
Harder Material
Previous 45 – 48 Rockwell
HCC is 68 Rockwell
Same life and appearance
Subjected new material to 500K lifecycle and salt bath test
Same performance as Chromed plug
Lower pricing and faster delivery!