Die casting is a manufacturing process that involves the production of complex shapes and components by injecting molten metal into a mold cavity under high pressure. The process requires proper design and calculation of the gate area to ensure the production of quality and accurate parts. This blog will provide a detailed guide on die casting gate area calculation, including its importance, factors that influence the gate design, and the steps involved in the calculation.
Importance of Gate Area Calculation in Die Casting
The gate is an essential component in the die casting process, as it serves as the channel through which the molten metal flows into the mold cavity. The gate design and size significantly influence the quality of the parts produced. It is, therefore, crucial to calculate the gate area accurately to prevent defects such as porosity, gas entrapment, shrinkage, and flash. Proper gate sizing also helps to optimize the casting process, reduce cycle time, and minimize production costs.
Factors Influencing Gate Area Design
Several factors influence the gate design, and they include:
Part geometry: The shape and size of the part to be cast determine the gate location and size.
Material type: The type of material used affects the fluidity and viscosity of the molten metal, which affects the gate size.
Wall thickness: The thickness of the part wall determines the gating system to use and the location and size of the gate.
Casting machine pressure: The pressure required to inject the molten metal into the mold cavity influences the gate design.
Surface finish: The desired surface finish affects the gate location and size.
Steps in Die Casting Gate Area Calculation
The following steps are involved in calculating the gate area for die casting:
Determine the part geometry and material type: The first step in gate area calculation is to determine the shape and size of the part to be cast and the type of material to be used.
Determine the casting machine pressure: The pressure required to inject the molten metal into the mold cavity is determined by the casting machine used.
Calculate the metal velocity: The metal velocity is calculated using the equation:
V = Q/A
Where V is the metal velocity, Q is the metal flow rate, and A is the cross-sectional area of the gate.
Determine the gate area: The gate area is calculated using the equation:
A = Q/V
Where A is the gate area, Q is the metal flow rate, and V is the metal velocity.
Choose the gate location: The gate location is chosen based on the part geometry, wall thickness, and desired surface finish.
Determine the gate size: The gate size is determined based on the gate location and the calculated gate area.
Design the gating system: The final step is to design the gating system, including the runner, sprue, and gate.
Clamping force calculation
F0=AxP/K
Total projection area A = casting projection area A1 + sprue area A2 (0.15~0.3A1) + discharge system A3 (0.1~0.2A1) + material shank area A4 (3.14xdxd d is the diameter of the material chamber and also both the diameter of the punch)
P Pressure injection ratio pressure (MPa) is the pressure per unit area, according to experience: 30~50 for general parts 50~80 for load-bearing parts 80~100 for gas-tight parts; also Below form for you Reference.
K is the insurance factor: 0.85
| Average Thickness | ≤2.5 | >2.5~4 | >4~6 | >6 |
| Aluminumalloy Time | 130~200 | 200~300 | 250~400 | 250~400 |
| Zinc Alloy Time | 300~500 | 500~800 | 800~1200 | 800~1200 |
The formula for calculating the internal gate cross-sectional area:
Ag = G / pVg t
Ag = cross-sectional area of the internal gate
G = mass of metal liquid passing through the inner gate
p = liquid aluminum density of 2.4g/cm3
Vg = flow rate of metal liquid through the inner gate
T = filling time
| Average Thickness | 0.8 | 1.27 | 1.5 2 | 1.9 | 2.28 | 2.54 | 2.79 | 3.175 | 3.81 | 4.57 | 5.08 | 6.35 |
| Aluminum alloy Time | 0.006 | 0.012 | 0.017 | 0.027 | 0.04 | 0.048 | 0.059 | 0.072 | 0.11 | 0.15 | 0.18 | 0.28 |
| Zinc Alloy Time | 0.004 | 0.008 | 0.011 | 0.017 | 0.026 | 0.032 | 0.038 | 0.050 | 0.072 | 0.105 | 0.125 | 0.205 |
| Average Wall Thickness | 0.8 | 1.27 | 1.5 2 | 1.9 | 2.28 | 2.54 | 2.79 | 3.175 | 3.81 | 4.57 | 5.08 | 6.35 |
| Aluminum Flow Rate | 48 | 46.2 | 45 | 43.5 | 42.6 | 42 | 41.1 | 40.5 | 39 | 37.5 | 36 | 33 |
| Zinc Flow Rate | 46.5 | 45 | 43.5 | 42 | 41.1 | 40.5 | 39.6 | 39 | 37.5 | 36 | 31.5 | 31.5 |
Die casting Clamping force calculation Examples
Products info:
Average Wall thickness: 4mm
Part Weight: 1.75kg
Total projection area A: 600.27cm2
Pressure injection ratio pressure (MPa): 60Mpa
Clamping Force F0=600.27*60/0.85=4235KN=423Ton; so we use 500Ton Die casting Machine.
internal gate cross-sectional area A=1.75/2.4*10-3*39*0.11=169.96mm2
Conclusion
Die casting gate area calculation is a critical aspect of the die casting process that influences the quality of the parts produced. The gate design and size significantly affect the casting process, and proper calculation helps to prevent defects such as porosity, gas entrapment, shrinkage, and flash. By considering the factors that influence the gate design and following the steps involved in the calculation, manufacturers can optimize the casting process, reduce cycle time, and minimize production costs.