We have talked many times in this column about the advantages air gaging brings to the manufacturing process, especially on the shop floor. In addition to their speed, ease of use and ability to automatically clean part surfaces before measuring, air gages are also capable of measuring to tighter tolerances than mechanical gages. At their very best, mechanical gages can measure down to 50 millionths, but that requires extreme care. Air gages handle 50 millionths with ease, and some will measure to a resolution of 5 millionths.
    我們在Gaging Tips（測量技術）這個專欄里多次提到過氣動量儀在生產過程尤其是車間里的測量優勢：除了速度快、操作簡便以及測頭的自潔能力外；相較機械量規，氣動量儀還能測量更小公差的工件；機械量規佳狀況下可測到0.00005’，但測量過程需極其謹慎小心，而氣動量儀則可輕松測到0.00005’，有時分辨率甚至可達0.000005’。

    When most people think of air gaging, they think of plugs. But a number of air ring and air fork styles provide the same benefits and some additional ones as well.
    一提到氣動量儀，大部分人腦子里浮現出的是氣動塞規，但其實很多氣動環規和氣動卡規也同樣可實現或完成更多測量任務。

    An air ring is the opposite of an air plug, and is primarily used to measure ODs. Air rings look quite simple—a steel ring with a pair of jets at a particular location—but there is a lot of engineering built into them. One trick is in calculating the size of the ring in order to achieve a good balance of clearance between the part and the opening in the ring. Too much clearance and your readout will start showing centralizing error. This happens when the part is shifted slightly in the tool and the air ring measures a chord rather than the diameter. Too little clearance and the indicator's range gets limited—or even worse—a geometry error can prevent the operator from inserting the part into the air tool.
    與氣動塞規測量內徑剛好相反，氣動環規主要用于外徑測量。其外觀看上去非常簡單——在一個在特定位置有一對噴氣孔的鋼圈，但其實其內部設計十分復雜。其中一項設計是用來計算環規的大小以確保工件和環規之間的間隙達到合適的平衡：間隙太大讀數經常容易出錯，因為當工件輕微移動時，環規測量到的數據只是外圓的弦長而并非直徑；若間隙太小，顯示范圍會受限甚至更糟——形位誤差容易導致操作者無法將工件插入氣動環規中。