# Design of gating system

Student at vit-east
2. Jul 2021
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### Design of gating system

• 2. Types of Gating System 1. Top Gate 2. Bottom Gate 3. Parting Line Gate 4. Step Gate 1. Directional Cooling 2. Fast Filling 3. Ferrous Casting 1. Minimum Turbulence 2. Reduce Erosion 3. Used for Deep Mold 1.Gradual Filling of MOLD 2. Heavy Casting 3. Small size of in gates in Compare to Runner
• 7. Gating Ratio • Gating ratio is used to describe the relative cross-sectional areas of the components of a gating system. • Pressurized Gating System:- Area of Sprue : Area of Runner : Area of in gate ( 1:2:1) This System is Gating Control System , because in gate Control the Flow Rate. Air Aspiration effect is minimum. Casting Yield is Maximum. Chances of turbulence.
• 8. Unpressurized Gating System • Gating Ratio is:- Area of Sprue : Area of Runner : Area of in gate( 1: 2: 2) This System Is Choke Control System, Choke area Controls the Flow Rate. Area of Choke will be:- Ac = W/ c.d.t( 2gh ) Air Aspiration effect is more than other System . Velocity is low, so Turbulence is minimum. Casting Yield is Minimum.
• 9. Question on Gating System Ques 1. The Pressure at the in-gate will be maximum with the Gating System a) 4:8:3 b) 1:3:3 c) 1:2:4 d) 1:2:1 (d)
• 10. Ques 2. A Mould has downsprue whose length is 20cm and the Cross Sectional area at the base of the downsprue is 1 cm2 . The downsprue feeds a horizontal runner leading into the mould cavity of volume 1000 cm3. The time required to fill the mould cavity will be a) 4.05 s c) 5.05 s b) 6.05 s d) 7.25 s (c) Ans :- Length of sprue h = 20 cm= 0.2m Area of down sprue A = 1 cm2. Volume of mould Cavity = 1000cm3 velocity at base of sprue V = 2gh = 1.98 m/s Let t is time of filling the mould then volume of mould cavity = A*v*t 1000cm3 = 1 cm2 x 1x1.98t => t = 5.05 s
• 11. Ques 3. In a gating System , the ratio 1: 2: 4 represents a) Sprue base area : runner area : in gate area b) Pouring base area : in gate area : runner area c) Sprue base area : in gate area: casting area d) Runner area : in gate area : casting area (a) Ques 4. The part of a gating system which regulates the rate of pouring of molten metal is a) Pouring basin b) Runner c) Choke d) In gate (c)