Inspection Detail

Inspection: 122197874 - Komatsu America Corp.

Inspection Information - Office: Peoria Area Office

Investigation Summary

On October 15, 1998, Employee #1, an electrician for Komatsu Mining Systems, Inc., and several coworkers were in Building AA, Machining Department 344, working on a Bullard 66 in. vertical turret lathe that was normally used to machine the EF2754 right steering arms for the model 930 truck. The operation normally performed on this machine involved boring an interior hole on the steering arm to a specific diameter. The arm was clamped down to the spindle table, then the entire table rotated while a turret arm equipped with a cutter on the end indexed over to the hole and bored the inside of it. This machine had been manufacturing this part for approximately three years at a frequency of approximately one order per month, with an order containing six to ten steering arms. This specific boring operation required approximately three days of machining time per order, with the Bullard running on the first and third shifts. Just before 7:00 a.m. on October 15, 1998, a coworker machinist had just completed the boring operation on a steering arm, removed the steering arm from the spindle table, and had clamped down another steering arm. A second machinist then started his shift by installing the tool/cutter in the turret arm, but when he tried to run the machine, it would not function. The acting maintenance supervisor was informed and, at approximately 9:00 a.m., a coworker electrician began working on the Bullard. A second electrician joined him at 1:00 p.m. Both electricians worked on the machine until 2:30 p.m., when they were pulled off the job to work on another piece of equipment. Both electricians felt the problem was due to the computer not reading the program tape. At approximately 3:00 p.m., Employee #1 started working on the Bullard. At 4:00 p.m., he asked for assistance from a coworker electrician, who stayed over to help work on the machine. They worked on the tape reader problem until about 5:15 p.m., when the new maintenance supervisor stopped by the machine to see if he could help. At this point, Employee #1 stated that he thought the machine couldn't carry out the tape command because the table was stuck in neutral, even though the control panel showed the table was in high. They shut down the controls and started them back up again. This time the controls showed that the table was in neutral. Employee #1 shifted the table into high range. The maintenance supervisor heard the table shift, but went behind the machine to confirm this. He told Employee #1 to jog the table, and Employee #1 tried to move the X and Z axis first, but they would not budge. He then tried to jog the table. The maintenance supervisor and the other electrician noticed that as the table began to turn, it quickly accelerated to an excessive speed. The maintenance supervisor yelled twice for Employee #1 to shut down the table and he saw Employee #1 pushing buttons on the control panel. The maintenance supervisor then went to the controls and pushed TABLE STOP. Immediately, a part broke loose from the chuck jaws and struck Employee #1 on the head, killing him. All three men were standing on the southeast side of the machine when the accident occurred, with the maintenance supervisor next to the control cabinet,

Keywords: HEAD, LATHE, REPAIR, UNSECURED, WORK RULES, ELECTRICIAN, STRUCK BY, FLYING OBJECT, MECH MALFUNCTION