The following factors must be considered while designing gating system.
(i) Sharp corners and abrupt changes in at any section or portion in gating system should be avoided for suppressing turbulence and gas entrapment. Suitable relationship must exist between different cross-sectional areas of gating systems.
(ii) The most important characteristics of gating system besides sprue are the shape, location and dimensions of runners and type of flow. It is also important to determine the position at which the molten metal enters the mould cavity.
(iii) Gating ratio should reveal that the total cross-section of sprue, runner and gate decreases towards the mold cavity which provides a choke effect.
(iv) Bending of runner if any should be kept away from mold cavity.
(v) Developing the various cross sections of gating system to nullify the effect of turbulence or momentum of molten metal.
(vi) Streamlining or removing sharp corners at any junctions by providing generous radius, tapering the sprue, providing radius at sprue entrance and exit and providing a basin instead pouring cup etc.
