Fig 2-9: plastic parts with side holes and side flutes 2.2. 1 Classification of Core-pulling mechanism Core-pulling mechanism usually comprises the following types Manual Pulling Manual pulling refers to the pulling of side-direction cores with hand or hand tools. Such mechanism is simple in structure yet low in productivity and large in labor intensity, See Fig 2-10 Fig 2-10: screw mandril manual side core-pulling mechanism 2. Hydraulic or Pneumatic Core-pulling Use pressure oil or compressed air as power, equipped the molds with special hydraulic or pneumatic tank, and achieve core-pulling through the to-and-fro movements of piston. The pulling force under such structure is large yet the cost is relatively higher. See Fig 2-11, 2-12 and 2-13 Fig 2-11: hydraulic(pneumatic)side core- Fig 2-12: hydraulic(pneumatic)side core- pulling mechanism for fixed half mold pulling mechanism forFig.2-9: plastic parts with side holes and side flutes 2.2.1 Classification of Core-pulling Mechanism Core-pulling mechanism usually comprises the following types: 1. Manual Pulling Manual pulling refers to the pulling of side-direction cores with hand or hand tools. Such mechanism is simple in structure yet low in productivity and large in labor intensity. See Fig.2-10. Fig.2-10: screw mandril manual side core-pulling mechanism 2. Hydraulic or Pneumatic Core-pulling Use pressure oil or compressed air as power, equipped the molds with special hydraulic or pneumatic tank, and achieve core-pulling through the to-and-fro movements of piston. The pulling force under such structure is large yet the cost is relatively higher. See Fig.2-11, 2-12 and 2-13. Fig.2-11: hydraulic (pneumatic) side core- Fig.2-12: hydraulic (pneumatic) side core￾pulling mechanism for fixed half mold pulling mechanism for moving half mold