Riser Modulus
Calculate the minimum modulus of a riser (feeder) by the modulus rule, M_riser = 1.2 × M_part, from the part's cooling modulus. The result, in cm, is the modulus the riser must have to solidify after the part (about 20% slower) and feed it with molten metal during solidification shrinkage, avoiding shrinkage cavities. The riser is a metal reservoir placed over the thickest region of the part; if it solidifies first, it fails its purpose. From the modulus, the riser geometry is sized. It is a fundamental rule of casting design. Enter the part's cooling modulus.
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Módulo do massalote
O massalote (também chamado montante, alimentador ou 'riser') é talvez o elemento mais importante para a sanidade interna de uma peça fundida. Trata-se de um reservatório extra de metal líquido posicionado sobre (ou ao lado de) a peça, conectado a ela. Sua função: à medida que a peça solidifica e contrai (o metal líquido ocupa mais volume que o sólido), o massalote fornece metal líquido adicional para preencher o vazio que a contração criaria — evitando o rechupe (uma cavidade interna de contração, o defeito mais comum e grave da fundição). Mas para o massalote cumprir essa função, ele tem que obedecer a uma regra de ouro: precisa solidificar DEPOIS da peça. Se solidificar antes, ele próprio fica sólido e não tem mais metal líquido para doar — e o rechupe se forma na peça. Como o tempo de solidificação depende do módulo (M = V/A, pela regra de Chvorinov o tempo ∝ M²), a condição se traduz numa exigência sobre os módulos: o módulo do massalote deve ser maior que o da peça. A regra prática consagrada é M_massalote ≈ 1,2 × M_peça (cerca de 20% maior), garantindo que o massalote solidifique por último com margem segura. A partir desse módulo-alvo, dimensiona-se a geometria do massalote (diâmetro e altura de um massalote cilíndrico, por exemplo, calculando V/A para atingir o módulo desejado). Há refinamentos: o massalote também precisa ter volume suficiente para alimentar toda a contração (critério de volume, além do critério de módulo), e existem massalotes exotérmicos/isolantes que, com camisas que retardam o resfriamento, atingem o módulo efetivo necessário com muito menos metal — melhorando o rendimento. O pescoço que liga o massalote à peça deve ter módulo intermediário (solidificar depois da peça mas antes do massalote) para que o caminho de alimentação permaneça aberto. Calcular corretamente o módulo do massalote é a essência do projeto de alimentação. Informe o módulo de resfriamento da peça.
Related Tools
Casting Cooling Modulus
Calculate the cooling modulus (or geometric modulus) of a casting, M = V ÷ A, dividing the volume V by the surface area A in contact with the mold. The result, in cm (length unit), is the parameter governing solidification speed: the larger the modulus, the slower the solidification (Chvorinov's rule says the time is proportional to the modulus squared). It is the basis of riser sizing in foundry — the modulus rule requires the riser modulus to be about 1.2 times that of the part, so it solidifies later and feeds the shrinkage, avoiding shrinkage cavities. Enter the part volume and area.
Solidification Volumetric Shrinkage
Calculate the volumetric shrinkage on solidification of a metal, ΔV = (ρ_solid − ρ_liquid) ÷ ρ_liquid × 100%, from the metal densities in the solid and liquid states. The result, in %, is the volume reduction that occurs when the metal goes from liquid to solid — because the solid is denser (more compact) than the liquid. This shrinkage is the main cause of shrinkage cavities (internal voids) and is exactly what risers must feed with extra molten metal. Each metal has its solidification shrinkage: steel ~3%, aluminum ~6.6%, copper ~5%. Gray cast iron is an exception (graphite expands, reducing the liquid shrinkage). Enter the solid and liquid metal densities.
Casting Metal Yield
Calculate the metal yield of a casting process, η = (part mass ÷ total poured mass) × 100%, dividing the finished part mass by the total poured metal (part + risers + runners + spills). The result, in %, measures the metal utilization efficiency: the rest (runners, risers, flash) is remelted, but consumes energy and adds cost. Typical yields range from 50 to 80%, depending on the part and gating complexity. Maximizing yield (well-sized risers, optimized gating) cuts energy and remelting costs. Enter the part mass and the total poured mass.
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.
Cat Food Quantity by Weight
Calculates daily grams of dry food for a cat by weight and life stage.
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.
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.