Document jBEGqyXV2qyYeRGOBEOdkDDyO

MACHINE TOOLS BENCH AND FLOOR STAND GRINDERS 6RINDERS (WHEEL CONTACT) BELOW t OF SPINDLE SWING-FRAME GRINDER CYLINDRICAL GRINDER SURFACE GRINDERS AND CUTTING-OFF MACHINES Fig 24-20 Maximum exposure ongles for various grinding applications Fig 24-21. Speed testing of grinding wheels is done in totally enclosed varia ble speed machines Safe speeds The various types of abrasive wheels and disks should be operated at speeds not ex ceeding those recommended by the manu facturer In particular, unmarked wheels of unusual shape, such as deep cups with thin walls or backs, or with long drums, should be operated according to the manufacturer's recommendatidns ' All wheels should be tested by the manu facturer (Fig 24-21) at specific testing speeds shown in Table 24-L Wheels which need not be tested include those less than 6 in in diameter, diamond wheels, mounted wheels, and other special types A letter of certification should accompany each speedtested wheel and the maximum operating speed should be clearly marked on the wheel. Before a wheel is mounted, the machine spindle should be checked for the correct 24-26