Amplification is how much an air gage magnifies a size change so you can read it. It sets the gage's range and how fine a reading you can see. Getting it right matters most when you replace a dial readout, because single-master tooling only reads correctly on a readout with matching amplification.
What amplification means
An air gage converts a tiny change in the gap between the jets and the part into a change in back-pressure or flow, and the readout turns that into pointer movement. Amplification is the ratio between the two. At 2,500:1, a .0001″ change in size moves the pointer .25″. At 10,000:1, the same change moves it a full inch.
Range versus resolution
Higher amplification spreads a smaller range across the whole dial, so each graduation is finer. Lower amplification covers a wider range with coarser graduations.
| Low amplification | High amplification | |
|---|---|---|
| Dimensionair models | D-2500 to D-8000 | D-10000 to D-32000 |
| Measuring range | Wider | Narrower |
| Graduations | Coarser | Finer |
| Typical use | Looser bore tolerances, more stock variation | Tight tolerances, finish bores, precision fits |
| Tool codes | 20, 50 | 5, 10 |
A common rule of thumb is that the gage should resolve about one-tenth of the tolerance, and the tolerance should use a good part of the measuring range so operators can see where the part sits.
Why single-master tooling is tied to one amplification
In a single-master system you set the gage on one master at nominal. The gage has no second master to tell it how far the pointer should move per unit of size, so that relationship is built into the tooling's jet design and the readout. That's why low-amp and high-amp tooling don't interchange, and why a replacement readout has to match the tooling group.
Two-master systems work differently. You set the gage on a minimum and a maximum master, and the readout calculates the amplification from them. That makes two-master readouts brand-independent. See single vs. dual master air gaging.
What changes with a digital readout
A dial readout is built for one amplification, so a plant often needs a D-2500, a D-5000 and a D-8000 for different parts. A digital readout shows the size as a number at the resolution you choose, up to 6 decimal places in inch or 4 in metric, with color tolerance zones.
The Air Gage Pro M5-L works with all low-amp tooling (D-2500 through D-8000) and the M5-H with all high-amp tooling (D-10000 through D-32000). That means fewer readout models to stock and one screen for operators to learn. Not sure which group you have? See how to identify your model, amplification and tool code.
Questions
What does 2,500:1 amplification mean?
A size change of .0001" moves the pointer .25" on the dial. The number is how many times the readout magnifies the change.
Is higher amplification more accurate?
It gives finer resolution over a smaller range. Accuracy also depends on the tooling, the masters, clean air and good technique. Pick the amplification that fits your tolerance.
Why don't low-amp plugs work on a high-amp readout?
In a single-master system the plug's jets and the readout are matched to one amplification. On the wrong readout the pointer moves the wrong distance for a given size change, so readings are wrong.
Does a digital readout need a set amplification?
A single-master digital readout still has to match the tooling group, which is why there is an M5-L and an M5-H. Within that group the display shows the value directly, so one unit covers several dial models.
Dimensionair, Mahr, MahrFederal, Federal and Western Gage are trademarks of their respective owners, used only to identify compatible equipment. Air Gaging LLC is not affiliated with or endorsed by them.