Mold Fill Time
Calculate the fill time of a casting mold, t = V ÷ Q, dividing the cavity volume V by the metal flow rate Q of the gating system. The result, in seconds, is the time to completely fill the mold with molten metal. It is a critical parameter: filling too slowly lets the metal cool and solidify before filling everything (cold shut, misrun defects), while too fast causes turbulence, gas entrapment, mold erosion and inclusions. The optimal time depends on the part's weight and thickness and the metal. Sizing the gating system for the right time is central to casting design. Enter the cavity volume and the flow rate.
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Tempo de enchimento do molde
O tempo de enchimento — quanto tempo o metal líquido leva para preencher completamente a cavidade do molde — é um dos parâmetros mais críticos da fundição, e seu cálculo básico é simples: t = V ÷ Q, o volume da cavidade dividido pela vazão de metal que o sistema de canais entrega. O que torna esse tempo tão importante é que ele tem uma janela ótima estreita, com defeitos graves em ambos os extremos. Se o enchimento for lento demais: o metal perde calor durante o trajeto e pode começar a solidificar antes de preencher tudo, causando falta de enchimento (misrun, a peça sai incompleta) ou junta fria (cold shut, duas frentes de metal já parcialmente solidificadas se encontram mas não se fundem, deixando uma linha de fraqueza). Seções finas são as mais vulneráveis. Se o enchimento for rápido demais: o metal entra com alta velocidade e turbulência, aspirando ar e gases (que ficam aprisionados como bolhas), erodindo as paredes do molde de areia (cujos grãos viram inclusões na peça), e oxidando a superfície do metal (formando 'escória' que contamina a peça). O tempo ótimo depende do peso e da espessura da peça (peças finas exigem enchimento rápido antes de solidificar; peças grandes toleram/precisam de mais tempo) e do metal (sua fluidez e faixa de solidificação). Existem fórmulas empíricas (como as de Caine ou as baseadas no peso) para estimar o tempo ideal, e a partir dele dimensiona-se a vazão necessária e, consequentemente, as áreas do sistema de canais. A simulação computacional de enchimento (mold filling) hoje permite visualizar o processo e otimizar o sistema antes de fundir. Informe o volume da cavidade e a vazão.
Related Tools
Gate Area
Calculate the gating channel section area, A = Q ÷ v, dividing the desired metal flow rate Q by the metal velocity v. The result, in the consistent area unit (cm²), is the cross-section the sprue (or gate) must have to deliver the needed flow at the calculated velocity. It is the application of the continuity equation to the casting gating system. Correctly sizing the areas of the system's elements (basin, sprue, runner, gates) controls the flow rate, velocity and flow regime of the metal, avoiding turbulence and ensuring proper filling. The ratios between the areas define the system type (pressurized or unpressurized). Enter the flow rate and the velocity.
Pouring Velocity
Calculate the molten metal velocity at the base of the sprue by Torricelli's equation, v = √(2·g·h), from the metal column height h (m) and gravity g. The result, in m/s, is the velocity at which the metal enters the gating system by gravity, starting from the pouring basin height. It is the basis of gating system design: the velocity sets the flow rate (with the section area) and the flow regime. Velocities too high cause turbulence (air aspiration, oxidation, erosion); hence gating systems are designed to control and slow the flow. Enter the metal column height.
Solidification Time (Chvorinov)
Calculate the solidification time of a casting by Chvorinov's rule, t = B × (V ÷ A)², from the mold constant B (min/cm², depending on the mold material and metal) and the ratio of the part's volume V to its surface area A. The result, in minutes, is the time for the metal to fully solidify. The rule shows that parts with a higher volume/area ratio (more 'massive') solidify more slowly — a fundamental casting design principle: risers (metal reservoirs) must have a larger modulus than the part to solidify last and feed the shrinkage. Enter the mold constant, the volume and the part area.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.