To let visitors better understand last technology information, here tell you what is GO - NO GO FIXED GAUGES, which we call Threaded plug gauge.
The GO - NO GO FIXED GAUGES is a kind of gauge. Used as a metric for high volume inspection products.
(1) For uniform inch thread, the external thread has three thread grades: 1A, 2A and 3A, and the internal thread has three grades: 1B, 2B and 3B, all of which are clearance fit. The higher the level number, the tighter the fit. In the inch thread, the deviation only specifies 1A and 2A, the deviation of the 3A is zero, and the grade deviation of the 1A and 2A grades is equal. The larger the number of grades, the smaller the tolerance, as shown in the figure: 1B 2B 3B Internal thread basic Medium diameter 3A external thread 2A 1A
1, 1A and 1B grade, very loose tolerance class, which is suitable for tolerance fit of internal and external threads.
2, 2A and 2B, is the most common thread tolerance class specified by the British series of mechanical fasteners.
3, 3A and 3B, screwing to form the tightest fit, suitable for tight tolerance fasteners, for critical design of safety.
4. For external threads, 1A and 2A have a tolerance, and 3A does not. The 1A tolerance is 50 greater than the 2A tolerance and 75 greater than the 3A. For the internal thread, the 2B tolerance is greater than the 2A tolerance by 30. The 1B is 50 greater than the 2B and 75 greater than the 3B.
(2) Metric threads, external thread has three thread grades: 4h, 6h and 6g, internal thread has three thread grades: 5H, 6 H, 7H. (The Japanese standard thread accuracy grade is divided into three grades I, II, and III, and the normal grade is grade II.) In the metric thread, the basic deviation of H and h is zero. The basic deviation of G is a positive value, and the basic deviation of e, f, and g is a negative value. As shown: Tolerance G H Internal thread deviation Basic medium diameter External thread f g h e
1. H is the common tolerance zone position for internal threads. It is generally not used as a surface coating or an extremely thin phosphating layer. The basic deviation of the G position is used for special occasions, such as thicker coatings, which are rarely used.
2, g is commonly used to plate 6-9um thin coating, such as the product drawing requirements of 6h bolts, the pre-plated thread uses a 6g tolerance band.
3, the thread fit is best combined into H / g, H / h or G / h, for bolts, nuts and other refined fastener threads, the standard is recommended to use 6H / 6g.
(3) Thread mark M10×1–5g 6g M10×1–6H Top diameter tolerance code Medium diameter and top diameter tolerance code (same) Medium diameter tolerance code.
The pass gauge is divided into two gauges and a gauge. For example, the thread of the M6-7h is a general gauge (T). If it can be screwed into the threaded hole, it is qualified, otherwise it is unqualified. Need to rework (that is, the hole is small). Then use the stop gauge (Z) if it can smoothly screw into the threaded hole for 2.5 turns or more, it is unqualified and vice versa. And the unqualified threaded hole should be scrapped at this time, can not be carried out Reworked. 2.5 circles is the national standard. If the export parts can only enter 1.5 laps (international standard). In general, the rules are only qualified, and the rules and regulations are all over or over. qualified.
For example, to check the size of the hole, the upper limit of the allowable deviation of the aperture is used as the end, and the lower limit of the allowable deviation of the aperture is used as the through end. If the end can pass the test, the aperture is large, unqualified, and cannot be reworked; If the end cannot pass, it means that the aperture is small and it is not qualified, but it can be qualified by reworking.
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