Protective guards

Grinding wheels must be guarded by appropriate protective guards on grinding machines. These guards must be capable catching broken wheel fragments effectively. Only that part of the wheel required for grinding may be left unprotected. Certain operations may require even the entire wor¬king area to be guarded.

The following wheel types may be operated without guards:

  • mounted wheels and points Type 52
  • cones and plugs with central threaded inserts Types 16 to 19
  • resinoid wheels Type 4 of diameter ≤ 200 mm

 

GUARDS FOR BENCH AND PEDESTAL GRINDERS

Fig. Guard for bench and pedestal grinders

Fig. Clearance between the periphery of the wheel and the adjustable guard and work rest

Fig. Rotating or pivoting internal guard

The maximum angle of aperture is 90°. The angle extending above the horizontal axis of the spindle must not exceed 65°

When using wheels with the diameter D > 150 mm, the guard should be of such a design that permits its adjustment so that the clearance between the periphery of the wheel and the end of the guard does not exceed 5 mm. Position of work rest must be adjustable as well.

Fixed bench and pedestal grinders that run at the speed 63 m/s or more may be equipped with additional internal guards. These internal guards are designed to close the aperture in the main guard in case of wheel breakage being moved down by the broken wheel fragments.

GUARDS FOR SWING FRAME GRINDERS

GUARDS FOR HAND HELD GRINDERS

Fig. Guard for swing type grinder

Fig. Guard for direct drive hand held grinder

Fig. Band type guard

A maximum aperture angle of the guard for the swing frame grinders should not exceed 180°. The guard must enclose at least half of the wheel on both sides.

GUARDS FOR DIRECT DRIVE HAND HELD GRINDERS
The maximum aperture should not exceed 185°. The guard must be so designed as to allow it to be opened (removed) on one side.

GUARDS FOR HAND HELD ANGLE AND FACE GRINDERS
Guards for type 27 grinding wheels should have a maximum aperture of 185°. They must be so designed as to be between the operator and the grinding wheel. In case of straight and taper cup wheels, the guards must be adjustable and positioned in such a way so that only one part of the wheel is left unprotected. When the protective band of the guard is adjustable the band is to be positioned so that the unprotected area T0, which is dependant on the thickness T of the grinding wheel, does not exceed the defined value. The clearance between the periphery of new grinding wheel and the protective band must not be greater than 6 mm.

GUARDS FOR CUTTING-OFF MACHINES

   

Fig. Guard for cutting-off machine

Fig. Adjustable guard of disc grinding wheel with threaded inserts

Fig. Adjustable guard of with abrasive segments

Guards for fixed cutting-off machines
Guards for fixed cutting-off machines. The maximum angle of the aperture is 150°. The guard must enclose the wheel on all sides with the exception of this aperture

TOTALLY ENCLOSED WORKING AREA

Fig. Example of a totally enclosed working area

In case of precision grinding performed at speed over 63 m/s the grinding wheel must be totally enclosed. When a totally enclosed guard is used, the workpiece is fed in mechanical way with complete safety. In addition, in case of wheel breakage, the fragments of the wheel cannot be thrown out.