Abstract: Employee #1, of Emco Fluids Systems, Valencia, CA, set up a grinder on a lathe and put an approximately 2 to 2.5 in. diameter abrasive wheel on it. He started the wheel and then went to get a cup of coffee. The wheel spun for approximately 5 minutes. When he returned, he moved the lathe; the wheel exploded without his even having touched it, fragmenting into pieces. A flying piece of the wheel struck Employee #1 on the upper left cheek near his eyes; if he had not been wearing safety glasses, he would have lost an eye. Employee #1 sustained a deep laceration and was taken to Henry Mayo Hospital in Valencia. He was referred to a plastic surgeon and received treatment immediately in the office of the plastic surgeon. At the time of the accident, the tool post grinder upon which the wheel was being operated was spinning at 36,000 rpm, but the abrasive wheel was rated by the manufacturer for a maximum of 8,275 rpm. Also, the wheel was not protected by a hood or by a guard.