Grinding wheels must be handled, mounted and used with the right amount of precaution and protection. They should always be stored so they are protected from banging and gouging. The storage room should not be subjected to extreme variations in temperature and humidity because these can damage the bonds in some wheels. Immediately after unpacking, all new wheels should be closely inspected to be sure they have not been damaged in transit. All used wheels returned to the storage room should also be inspected. Wheels should be handled carefully to avoid dropping and bumping, since this may lead to damage or cracks. Wheels should be carried to the job, not rolled. If the wheel is too heavy to be carried safely by hand, use a hand truck, wagon or forklift truck with cushioning provided to avoid damage.
Before mounting a vitrified wheel, ring test it as explained following must required. The ring test is designed to detect any cracks in a wheel. Never use a cracked wheel. A wise precaution is to be sure the spindle rpm of the machine you are using doesn't exceed the maximum safe speed of the grinding wheel.
Always use a wheel with a center hole size that fits snugly yet freely on the spindle flange without forcing it. Never attempt to alter the center hole. Use a matched pair of clean, recessed flanges at least one-third the diameter of the wheel. Flange bearing surfaces must be flat and free of any burrs or dirt buildup. Tighten the spindle nut only enough to hold the wheel firmly without over-tightening. If mounting a directional wheel, look for the arrow marked on the wheel itself and be sure it points in the direction of spindle rotation. Always make sure that all wheel and machine guards are in place, and that all covers are tightly closed before operating the machine. After the wheel is securely mounted and the guards are in place, turn on the machine, step back out of the way and let it run for at least one minute at operating speed before starting to grind.
Grind only on the face of a straight wheel. Grind only on the side of a cylinder, cup or segment wheel. Make grinding contact gently, without bumping or gouging. Never force grinding so that the motor slows noticeably or the work gets hot. If a wheel breaks during use, make a careful inspection of the machine to be sure that protective hoods and guards have not been damaged. Also, check the flanges, spindle and mounting nuts to be sure they are not bent, sprung or otherwise damaged.
Ring Test
If the wheel is not too heavy, it may be suspended from the hole on a small pin or the finger. Heavier wheels may be allowed to rest in a vertical position on a clean, hard floor. “Tap” the wheel gently with a non-metallic implement such as a wooden screw driver handle for light wheels and a wooden mallet for heavy wheels. The best spot to “tap” a wheel for the ring test is about 45 degrees either side of the vertical center line and about 1 or 2 inches from the periphery. If struck directly along the vertical center line, the “ring,”, even in a sound wheel, is sometimes muffled and may give the erroneous impression that the wheel is cracked. This is especially true with large wheels which are supported on the floor when conducting this test. It is sometimes noticeable also when the wheel is suspended from the hole. It is recommended that the test be repeated after rotating the wheel 45 degrees to the right or left.
Repeat this “ring test” immediately before mounting-either a new or used wheel on a machine, especially if the wheel has been in storage or out of service for a considerable time. In making this test it must be realised that wheels bonded with organic material do not give forth the same clear metallic sound as do vitrified and silicate wheels. Also wheels must be dry and free from sawdust when applying the test, otherwise the sound will be deadened. Comparison of the sound with other wheels of the same lot and specification will allow rejection of any wheel with a suspiciously different ring before use.
Before mounting a vitrified wheel, ring test it as explained following must required. The ring test is designed to detect any cracks in a wheel. Never use a cracked wheel. A wise precaution is to be sure the spindle rpm of the machine you are using doesn't exceed the maximum safe speed of the grinding wheel.
Always use a wheel with a center hole size that fits snugly yet freely on the spindle flange without forcing it. Never attempt to alter the center hole. Use a matched pair of clean, recessed flanges at least one-third the diameter of the wheel. Flange bearing surfaces must be flat and free of any burrs or dirt buildup. Tighten the spindle nut only enough to hold the wheel firmly without over-tightening. If mounting a directional wheel, look for the arrow marked on the wheel itself and be sure it points in the direction of spindle rotation. Always make sure that all wheel and machine guards are in place, and that all covers are tightly closed before operating the machine. After the wheel is securely mounted and the guards are in place, turn on the machine, step back out of the way and let it run for at least one minute at operating speed before starting to grind.
Grind only on the face of a straight wheel. Grind only on the side of a cylinder, cup or segment wheel. Make grinding contact gently, without bumping or gouging. Never force grinding so that the motor slows noticeably or the work gets hot. If a wheel breaks during use, make a careful inspection of the machine to be sure that protective hoods and guards have not been damaged. Also, check the flanges, spindle and mounting nuts to be sure they are not bent, sprung or otherwise damaged.
Ring Test
If the wheel is not too heavy, it may be suspended from the hole on a small pin or the finger. Heavier wheels may be allowed to rest in a vertical position on a clean, hard floor. “Tap” the wheel gently with a non-metallic implement such as a wooden screw driver handle for light wheels and a wooden mallet for heavy wheels. The best spot to “tap” a wheel for the ring test is about 45 degrees either side of the vertical center line and about 1 or 2 inches from the periphery. If struck directly along the vertical center line, the “ring,”, even in a sound wheel, is sometimes muffled and may give the erroneous impression that the wheel is cracked. This is especially true with large wheels which are supported on the floor when conducting this test. It is sometimes noticeable also when the wheel is suspended from the hole. It is recommended that the test be repeated after rotating the wheel 45 degrees to the right or left.
Repeat this “ring test” immediately before mounting-either a new or used wheel on a machine, especially if the wheel has been in storage or out of service for a considerable time. In making this test it must be realised that wheels bonded with organic material do not give forth the same clear metallic sound as do vitrified and silicate wheels. Also wheels must be dry and free from sawdust when applying the test, otherwise the sound will be deadened. Comparison of the sound with other wheels of the same lot and specification will allow rejection of any wheel with a suspiciously different ring before use.
