The 3 D’s of Straightness Plugs
We have touched on the many different applications of air gaging in a number of articles: size, match gaging, and form applications such as taper. In this column, we will discuss air straightness plugs and how they work.
The typical out-of-straightness condition is seen as a “bow” form within the bore, one that was introduced as part of the manufacturing process. The air straightness plug attempts to measure the depth of its curve. Usually, this out-of-straightness condition is all within one orientation along the axis of the hole.
Design
A typical air plug has four measuring jets in two opposing sets—two near the middle and two near the ends, as seen in Figure 1. This design allows the plug to look at both extremes of the bow condition.
There are no rules for the exact positioning of the jets relative to each other—as is sometimes the case with taper or squareness checks. Nor are there any ratios involved. The air jets at the extreme of the plug are positioned to inspect for the out-of-straightness condition which is usually specified over the total length of the bore. But, in order to understand how a straightness plug works, we have to take a quick look at the various combinations of jets typical in air tooling.
To read the remainder of this article, CLICK HERE.
Air Gaging from Mahr Inc.
Air Gaging is the inspection tool that allows you to measure many jobs faster, more conveniently and more accurately than other gaging methods. In the measurement of all hole conditions, air gaging is unsurpassed for speed and accuracy. In checking any dimensional characteristic, air offers sufficient magnification and reliability to measure tolerances well beyond the scope of mechanical gages.
For more information about Air Gages, CLICK HERE.
