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(shù)）這個(gè)專欄里多次提到過氣動量儀在生產(chǎn)過程尤其是車間里的測量優(yōu)勢：除了速度快、操作簡便以及測頭的自潔能力外；相較機(jī)械量規(guī)，氣動量儀還能測量更小公差的工件；機(jī)械量規(guī)佳狀況下可測到0.00005’，但測量過程需極其謹(jǐn)慎小心，而氣動量儀則可輕松測到0.00005’，有時(shí)分辨率甚至可達(dá)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(xiàn)出的是氣動塞規(guī)，但其實(shí)很多氣動環(huán)規(guī)和氣動卡規(guī)也同樣可實(shí)現(xiàn)或完成更多測量任務(wù)。

    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(guī)測量內(nèi)徑剛好相反，氣動環(huán)規(guī)主要用于外徑測量。其外觀看上去非常簡單——在一個(gè)在特定位置有一對噴氣孔的鋼圈，但其實(shí)其內(nèi)部設(shè)計(jì)十分復(fù)雜。其中一項(xiàng)設(shè)計(jì)是用來計(jì)算環(huán)規(guī)的大小以確保工件和環(huán)規(guī)之間的間隙達(dá)到合適的平衡：間隙太大讀數(shù)經(jīng)常容易出錯(cuò)，因?yàn)楫?dāng)工件輕微移動時(shí)，環(huán)規(guī)測量到的數(shù)據(jù)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(dǎo)致操作者無法將工件插入氣動環(huán)規(guī)中。