This document discusses different types of gating systems used in metal casting and their design considerations. It describes top gates, bottom gates, parting line gates, and step gates. It then covers gating ratios for pressurized and unpressurized systems. Pressurized systems use a 1:2:1 ratio of sprue to runner to ingate areas to control flow. Unpressurized systems use a 1:2:2 ratio with the choke controlling flow. It provides examples of questions on gating systems and their components.

1. 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

3. Design of Top Gate

5. Design Of Bottom Gate

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)