Taps offered in our catalogue are produced in the basic class destined for the most common use of inner thread: for metric thread - 6H, for unified th

Taps offered in our catalogue are produced in the basic class destined for the most common use of inner thread: for metric thread - 6H, for unified threads UNC, UNF - 2B, for Whitworth threads BSW, BSF - „normal”. Producing in other classes can be done by order. Taps classes (i.e. working part tolerance zones) for metric thread are unified by international and domestic standards. The determined tap class allows to obtain the threads of two or three tolerance zones (see picture and table below). Internal thread Internal thread Tolerance H limits Tap tolerance limits Tolerance G limits 8G EI=0 8H ISO2 ISO1 ISO3 CO о Tolerance class of the tap according to standard: PN - 72 PN - 92 DIN 802 Tolerance range of the internal thread M- 57800 M- 57800 1A ISO1 4H 4H 5H - 2A ISO2 6H 4G 5G 6H 3A ISO3 6G 6G 7H 8H 7G - 7G 8G ) Polish Standard following the international standard ISO, provides only three classes of taps, whereas the standard DIN 802 introduces additionally the fourth class 7G for “loose” threads. Furthermore, the standard Din 802 provides the possibility of correction the tap tolerance comparing to the standard demands in case when it is required by the particular machining conditions, e.g. the sort of machining material. In such situation the symbol of the tap's class with the sign “X”, e.g. 6HX, 6GX is obligatory. Q 286 TECHNICAL INFORMATION 3.4. Taps classes and inner thread’s tolerance zone