Design of a breaking machine for separating pairs of high chromium grinding ball media

A high chromium grinding ball media coded NF6357A is a replacement casting produced by Nigerian Foundries limited, Lagos, Nigeria for cement mill grinding. The 30 mm diameter ball casting is produced by machine moulding. The balls come out in pairs after shakeout, and must be separated and heat-treated before delivery to the customers. In this study, a separating machine is designed to break the adjoining area of the pairs into a unit to overcome the challenges of the existing manual breaking. The machine composed of electric motor with reducer gear, chute/chute support, hammer and pulley. The ball pairs are manually fed into the chute and move by gravity for breaking by impact force of the hammer. The hammer is bolted firmly on the rotating pulley to hit the balls against the chute edge. Each separated unit of the ball falls off for collection and subsequent grinding/finishing operations. The breaker is designed to separate twenty (20) pairs of balls in about 7 minutes with shearing stress of about 450 N/mm2 and capable of producing 4.5 KN impact force. This breaking shear stress is sufficient enough to overcome the shear strength of the grinding media which is about 379 N/mm2.