Foundry Melt Loss Calculator: Metal Lost, Cost per Heat and Annual Savings
Melt loss is the weight of metal you charge that never reaches the ladle. It leaves as slag, dross, oxide, spillage and vaporised alloy. Because it is a percentage of every heat, small improvements pay back across thousands of heats a year.
Your numbers
Total weight of metal charged including returns and additions.
(Charge minus tapped metal) divided by charge. Includes slag, dross, oxidation and spills.
Blended cost of the charge mix, not just the purchased metal.
Percentage points you hope to remove, for example 3.0 to 2.5 is 0.5.
Your results
Excludes energy, flux and labour. Add those to see the full cost of remelting.
Annual cost of melt loss vs loss percent
Sweeps Melt loss from 0.5 to 8, holding your other inputs fixed.
Batch yield reporting for melt decks
Optional: a review of how heats and yields are captured in your ERP or MES.
Optional. The tool and every export work without this. No spam.
How to use it
Weigh the full charge for a heat and the tapped or poured metal, then compute loss as a percentage. If you cannot weigh tapped metal, use the sum of castings, gating and returned ladle skulls. Enter your blended metal cost, heats per month and a target reduction. The annual figure shows what melt loss costs you, and the saving figure shows what each tenth of a point is worth.
Typical drivers of loss
Loss differs by alloy and furnace. Aluminium loses metal as dross and is hit by fines, turnings and coated scrap with a high surface area. Iron and steel lose through oxidation of silicon, manganese and carbon, rusty or oily scrap and slag volume. Melting time, holding temperature and open bath time all matter, so do charge density and furnace condition.
- Fine or oily scrap has far more loss than dense bundles
- Long holding at high temperature burns alloy
- Skimming too hard carries metal out with dross
- Over-sized heats left idle repeatedly cool and remelt
Reading the result
Compare the annual figure to your yearly metal spend and to the cost of options that reduce loss, such as scrap briquetting, dross presses, cover fluxes, charge preheating or lids on holding furnaces. A half-point saving on a large foundry can fund a modest project, but verify that measured loss really falls, because weigh scale error can hide or invent a gain. Track loss per furnace and per alloy so the data is comparable.
Common mistakes and ERP notes
A frequent mistake is using the loss percent of a single heat as if it were typical. Take a rolling average over many heats. Another is valuing lost metal at scrap price instead of charge cost. In the ERP, melt loss usually appears as a variance on the melt batch or process order, comparing charged material to output. If it is not recorded by heat, cost accountants only see it as an unexplained inventory difference at month end.
Frequently Asked Questions
What is a normal melt loss for iron or aluminium?
It varies with furnace and charge quality. Many induction iron operations see low single digit percentages, while aluminium can range from around one to several percent depending on scrap type and fluxing. Measure your own heats.
How is melt loss calculated?
Subtract tapped or accounted metal from charged metal, divide by charged metal and multiply by 100. Use enough heats to smooth out scale error and timing differences between charging and pouring.
Does melt loss include slag metal that is recovered?
Count only metal that is permanently lost. If dross is processed externally and metal is returned, credit that recovery. Otherwise you will overstate the loss and undervalue the dross handling process.
How do I value alloy elements burned off?
Alloy burn-off is a separate cost because the lost element is often more expensive than the base metal. Track it by spectrometer before and after the heat and add ferroalloy replacement cost to your analysis.
If melt heats are not reconciled in your ERP, we can help set up batch level charge and yield reporting so loss shows up by furnace and alloy.
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