How to use this calculator
- Enter poured metal basis. Enter net casting mass, target yield, alloy density and desired pour time.
- Set the flow head. Enter effective metal head at the choke and the discharge coefficient used for the screen.
- Enter the gating ratio. Enter sprue, runner and ingate ratio parts, then the number of ingates sharing the total ingate area.
- Check areas and velocity. Use choke area, runner area, ingate area and ingate velocity utilization as a first-pass methoding check.
How it works
The calculator starts from the entered casting yield: m_p = m_c / (Y / 100) It converts total poured mass to volume with the entered density, then divides by pour time: Q = (m_p / rho) / t This keeps gates, runners, risers and remelt allowance visible instead of hiding them in the casting weight.
Choke area uses the common orifice-style screen: A_choke = Q / (C_d * sqrt(2 * g * h)) Runner and ingate totals are scaled from the entered area ratio: A_runner = A_choke * R_runner / R_sprue A_ingates = A_choke * R_ingate / R_sprue The individual ingate area is the total ingate area divided by the entered ingate count.
Worked example
Verified against the live calculator
Suppose a 10 kg aluminum casting is screened at
55% yield, density 2700 kg/m3,
pour time 30 s, effective head 150 mm
and C_d = 0.70. Total poured metal is
10 / 0.55 = 18.18 kg, or about
0.006734 m3. The volume pour rate is therefore
0.006734 / 30 = 0.0002245 m3/s.
The head velocity is
0.70 * sqrt(2 * 9.80665 * 0.150) = 1.20 m/s.
The choke area is about 187 mm2. With a
1:2:4 sprue:runner:ingate ratio, total runner area is
about 374 mm2 and total ingate area is about
748 mm2. Four ingates put each ingate near
187 mm2, with ingate velocity near
0.30 m/s.
Frequently asked questions
What does the casting gating system calculator size?
It estimates total poured metal, pour rate, choke area, total runner area, total ingate area and area per ingate from casting mass, yield, density, pour time, effective head, discharge coefficient and gating ratio.
How is choke area calculated?
The calculator converts total poured metal into volume, divides by pour time to get Q, then uses A_choke = Q / (Cd*sqrt(2*g*h)). Effective head and Cd are user-entered because sprue, basin and choke details control the real flow.
What does the gating ratio mean?
The entered sprue:runner:ingate ratio is interpreted as total area ratio. For example, 1:2:4 makes total runner area twice the choke-area basis and total ingate area four times that basis before dividing by the ingate count.
Can this replace foundry methoding or simulation?
No. This is a transparent formula worksheet for early screening. Final gating still depends on alloy, casting geometry, sprue taper, choke placement, turbulence, oxide control, riser feeding, mold practice, simulation and production trials.
Method & assumptions
- Casting yield is entered as net casting mass divided by total poured metal mass.
- Metal density is user-entered; no alloy or temperature table is embedded.
- Effective head is the head acting at the choke, not necessarily ladle height or sprue top height.
- Discharge coefficient is an empirical loss allowance and should come from foundry practice when available.
- The gating ratio is interpreted as total sprue:runner:ingate area ratio.
- No turbulence, oxide entrainment, aspiration, choke placement, sprue taper, mold fill simulation, shrinkage feeding, riser neck, alloy freezing range, chills or production-trial result is modeled.