Metal Head at Choke Section of Sprue Calculator

Formula:

\[ h_c = h_t \times \left(\frac{A_t}{A}\right)^2 \]

Metal Head at Top Section (h_t):

Area at Top Section (A_t):

m²

Area of Sprue in Choke Section (A):

m²

Head at Choke Section (h_c): m

1. What is Metal Head at Choke Section of Sprue?

Definition: The vertical height of molten metal above the narrowest point (choke) in the gating system of a casting, crucial for ensuring proper flow and filling of the mold cavity.

Purpose: It helps foundry engineers determine the proper metal head required for complete mold filling during casting processes.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ h_c = h_t \times \left(\frac{A_t}{A}\right)^2 \]

Where:

\( h_c \) — Head at choke section (meters)
\( h_t \) — Metal head at top section (meters)
\( A_t \) — Area at top section (square meters)
\( A \) — Area of sprue in choke section (square meters)

Explanation: The formula calculates the required metal head at the choke section based on the principle of continuity and Bernoulli's equation.

3. Importance of Metal Head Calculation

Details: Proper calculation ensures complete mold filling, prevents casting defects like misruns or cold shuts, and optimizes metal flow in the gating system.

4. Using the Calculator

Tips: Enter the metal head at top section, area at top section, and area of sprue in choke section. All values must be > 0. Results include ±5% tolerance.

5. Frequently Asked Questions (FAQ)

Q1: Why is the choke section important in casting?
A: The choke section controls metal flow rate and ensures proper filling of the mold cavity.

Q2: What happens if h_c is too low?
A: Insufficient metal head can lead to incomplete filling of the mold, resulting in casting defects.

Q3: How does sprue area affect the metal head?
A: Smaller sprue area at choke increases velocity but requires greater metal head to maintain flow.

Q4: What's the typical tolerance for these calculations?
A: Most foundries work with ±5% tolerance for metal head calculations.

Q5: Can this be used for all casting metals?
A: Yes, but density and viscosity effects should be considered for non-ferrous metals.