Fettling cast components with a pedestal grinder.
A foundry used a large pedestal grinder to remove flash and other unwanted material from aluminium castings. In this process, an operator holds the casting in both hands and supports it in a fixture while pushing it, with some force, against the grinding wheel. The fixture was supported by a flimsy fabricated bracket mounted on the body of the grinder. Mechanical vibrations, due to out-of-balance forces in the machine, caused the bracket to resonate which in turn caused the fixture and the casting to vibrate. This transmitted vibration magnitudes of more than 20 m/s2 to the operator's hands.
A firm of consultants was employed to investigate the cause of the vibration and find a solution. The casting fixture support bracket was identified as the principal cause of the problem. A replacement was designed with a more rigid construction to be mounted directly on the floor rather than on the machine. The new bracket was made and fitted by the company's own engineering staff.
£0 for materials. Approximately half a day's labour plus consultant's time.
Case courtesy of Industrial Noise and Vibration Centre