Method for manufacturing golf ball

A method of removing flash from the parting line on the surface of a golf ball formed of a thermoplastics resin cover material having a hardness of Shore D 40 to 75 comprising the steps of:

• securing said golf ball for movement limited to rotation about an axis perpendicular to said parting line;
• continuously rotating said golf ball about said axis whereby said surface of said golf ball at said parting line moves at a speed of between 100 and 600 mm/sec;
• providing a grinding tool having a grinding face which is substantially parallel to said rotational axis of said ball;
• moving said grinding face at a speed of between 2400 and 6900 mm/sec in a direction opposite to the direction of movement of said golf ball parting line resulting from rotation of said golf ball;
• moving said grinding tool with respect to said golf ball to place said grinding face of said tool in grinding contact with said parting line, whereby, at a point of contact between the grinding face of said tool and the parting line of said golf ball, said grinding face and said parting line move in opposite directions at a relative velocity of between 2500 mm/sec and 7500 mm/sec;
• and
• grinding said flash from said parting line;
• and
• providing a sucking pipe having a sucking mouth which opens adjacent the parting line and removing shavings ground from said golf ball surface as said ball is ground.