The possibility of serious injury in grinding comes from the easy occurrence of negligence: running the grinding wheel at super high speed. When the grinding wheel is operated at a speed much higher than the rated maximum speed, it is likely to break within a few minutes of operation, and if the grinding wheel runs at a slightly higher speed than its rated speed, it may also be dangerous. This not very severe overspeed condition may cause damage to the grinding wheel, which in turn may cause chipping after further use. For example, running a reinforced 9-inch diameter, 27-type maximum rated speed of 6,600 r/min on a 7-inch angle grinder at 7,700 r/min may cause cracks in the wheel. Such cracks may cause cracking in the future. The following actions may also cause an overspeed condition: - Mounted on a sander, such as a "gun-shaped" pneumatic sander;
- Install the grinding wheel directly on the motor;
- Install a grinding wheel on a machine tool with incorrect grinding wheel specifications;
- The machine components are not properly maintained, especially the controllers on pneumatic machines and the connection mechanisms on floor-standing machines;
- Use an incorrect air source, hydraulic source or power source;
- Use improperly set machine speed.
![]() Operating the grinding wheel at ultra high speed may cause the grinding wheel to rupture. The crack on the illustrated grinding wheel is generated when the grinding wheel is operated at an ultra-high speed, which may cause an accident. |
Any of the above actions can lead to catastrophic situations that can lead to serious casualties. The danger of running at overspeed is due to centrifugal force. As a result of the rotational motion, the centrifugal force is the force that causes the weight to tighten the rope when the weight at the end of the rope makes a circular swivel motion. When the grinding wheel is rotating, the same force will cause the weight of the grinding wheel to pull the grinding wheel away from the center of rotation. The fact that the centrifugal force does not increase in proportion to the speed rise, but instead increases as the square of the speed rise, leads to the danger. When the speed of the selection doubles, the centrifugal force will increase by four times. This effect means that relatively small changes in speed can lead to a huge increase in force. In the above-mentioned example, the speed was changed from 6,600 r/min to 7,700 r/min, and the rate of increase in speed was 1.167. The corresponding centrifugal force increase rate is 1.167 × 1.167, or 1.36. Let's look at a more extreme example, considering the same grinding wheel with the highest safe operating speed of 6,600 r/min and running at 10,000 r/min on a 5 inch right angle grinder. This means running at a speed 1.5 times faster than the design speed of the grinding wheel. However, the corresponding centrifugal force - and the corresponding rotational stress on the grinding wheel - will be approximately 2.3 times the maximum permissible value. In short, do not run beyond the rated speed of the wheel. The speed of the grinding machine must be compared to the speed marked on the grinding wheel or package to ensure that the speed of the machine is equal to or lower than the maximum operating speed of the grinding wheel. Exceeding this rating will not only cause the grinding wheel to rupture, but may also endanger the personal safety of the workshop personnel.
Computer Display Hydraulic Universal Testing Machine
Testing Machine,Material Testing Machine,Screw Bolt Tensile Testing Machine,600Kn Hydraulic Universal Testing Machine
Jinan Chenda Testing Machine Manufacturing Co., Ltd. , https://www.jncdtester.com