Каталог Iscar вращающийся инструмент 2017 - страница 732

USER GUIDE TAPS Tap Tolerances Tolerance classes of taps and tolerance positions Nut thread Tolerance Nut thread for screw threads as per ISO metric standard. positioning of classes for positioning of H tolerance taps G tolerance 8H 7G 7H 6G 6H 5G 5H 4G 7G 4H 6G 6H =0 4H Tap tolerance Nut threads Au according to Au H tolerance Basic Pitch Diameter D2 D2 Au = Basic Deviation of Pitch For Optimum Tapping Conditions, Reduced Machining Times and Increased Tap Life Selection of the Most Suitable Tap Tapping Speeds As a general rule, materials with deformation capability of The tapping speed has a great influence on chip flow at least 10% can be cold-formed. and the life of the tap. To decide on the most suitable tap, please refer to the tap It is worthwhile to establish the ideal speed by recommendation table on page 706. tapping trials. For recommended initial values, see table on Pre-Tapping Holes page 706. In addition, the following should be taken into Check that the holes are within the prescribed size range consideration: characteristics of the material, machine depending on the application (see table on page 720) The and clamping method. holes should be clean and swarf-free. Effects of Unsuitable Tapping Speed Lubrication • forced tapping Frequently the lubricant content of the coolant used for • tap lead chipping caused by overloaded cutting tooth general machining is too low for tapping. • torn threads • If it is not possible to increase the lubricant content, • unsatisfactory tap life following are some possible solutions: • rejected threads • A separate Iubricating unit can be connected to the machine control, to deliver the required quantity of concentrated emulsion into the core hole or onto the tap. Tapping in separate operations allows the use of the ideal tapping lubricant. 728 728 ISCAR ISCAR