To ensure the hot runner system operates stably over the long term, it’s essential to first accurately determine “how much heat is required” and “how much heat will be lost.” The current industry standard divides the calculation into two steps: “heating power P₁” and “steady-state compensation power P₂.”

1. Heating power P₁: In the formula P₁ = m·c·ΔT / (60·η·t), m represents the mass of the distribution plate (in kg); c is taken as 0.48 kJ/(kg·℃); ΔT is the temperature difference between room temperature and the operating temperature; η is the efficiency coefficient, ranging from 0.47 to 0.56; and t is the target heating time (typically 20–30 minutes). Taking as an example a H13 distribution plate weighing 20 kg, with ΔT = 180 ℃, η = 0.5, and t = 25 minutes, we get P₁ ≈ 4.6 kW.

2. Steady-state compensation power P₂: Heat conduction Qp, convection Qk, and radiation Qs must be calculated separately.
   • Heat conduction: Qp = λ·Ap·ΔT/s, where λ is the thermal conductivity of steel, 45 W/(m·K); Ap is the contact area; and s is the gasket thickness. If four titanium alloy pressure-bearing gaskets, each measuring Φ20 mm × 5 mm, are used, with Ap = 12.6 cm², then Qp ≈ 203 W.
   • Convection: Qk = αk·Ak·ΔT, where αk is taken as 8 W/(m²·K), Ak is the exposed area of the distribution plate, which is 0.25 m², and Qk ≈ 360 W.
   • Radiation: Qs = ε·σ·As·(T₁⁴–T₂⁴). For polished aluminum foil, ε = 0.18, As = 0.25 m², T₁ = 473 K, and T₂ = 333 K; therefore, Qs ≈ 145 W.
   The total steady-state heat loss Qloss = Qp + Qk + Qs ≈ 708 W; therefore, P₂ ≥ 0.71 kW. The final rated power of the heater P = (P₁ + P₂) × 1.2 (safety factor) ≈ 6.4 kW.
   Field verification shows that, after selecting the model according to this approach, the分流 plate can be heated from 20 ℃ to 200 ℃ within 30 minutes and maintain a constant temperature within ±1 ℃. Compared with the empirical method, energy consumption is reduced by 18%, and the lifespan of the heating rods is extended by 25%.