Обший каталог Yamawa 2016 - 2017 - страница 786

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Length of engagement Description of products ■Length of engagement Thread tolerance class is chosen in consideration of "engagement classification" and "engagement length". To realize the stable tapping, it is necessary to fully understand the relation between these factors and to choose the suitable tolerance class. On "engagement calssification : middle", the tolerance class 6H is almost always chosen for standard internal threads. However, in case of "engage- ment length : L", tolerance class 7H can also be chosen. On M12x1.75, the tolerance of 7H is 25% (50μm) larger than that of 6H. And this widens the selection range of the tolerance class for taps to customer's advantage. M12x1.75 6H Pitch diameter : 10.863 ~ 11.063mm (tolerance 0.200 mm) 7H Pitch diameter : 10.863 ~ 11.113mm (tolerance 0.250 mm) 1) Engagement classification classification application fine precise screw threads with a little allowance middle standard screw threads used for machines, apparatuses and constructions bodies coarse screw threads used for construction and building installation, and screw threads for which threading operation is very difficult such as threading of hot rolled steel bars. 2) Classification of engagement length symbol classification limit size engagement length S short up to and including 2.24Pd0.2 N normal over 2.24Pd0.2 up to and including 6.7Pd0.2 L long over 6.7Pd0.2 internal thread 3) Selection rule of internal threads and external threads d : size designation external Selection rule of the tolerance class of internal threads thread tolerance position H engagement length S N L engagement classification fine 4H 5H 6H middle 5H 6H 7H coarse - 7H 8H P : pitch Selection rule of the tolerance class of external threads tolerance position h g engagement length S N L S N L engagement classification fine (3h4h) 4h (5h4h) - - - middle (5h6h) 6h (7h6h) (5g6g) 6g (7g6g) Technical Information coarse - - - - 8g (9g8g) Technical-11 782