DURING KILN SHUTDOWN, EMPLOYEE WAS HELPING PRODUCTION HELPER LIFT A 5 GALLON BUCKET OF 4"" BY 7"" STEEL SHIMS ONTO BACK OF TOW MOTOR, WHEN HE SMASHED HIS RIGHT MIDDLE FINGER BETWEEN THE BUCKET A ND THE TOW MOTOR. BUCKET WEIGHED APPROX 100-125 LBS. THIS CAUSED A 90% AVULSION OF THE FINGERTIPON HIS RIGHT MIDDLE FINGER. EMPLOYEE PLACED ON LIGHT DUTY.