BIZOMAT MAKEOS · Materials
Melt Charge Blend (Two Materials to a Target Content, Batch Masses, Cost)
How much of each of my two charge materials do I melt to hit the target alloy content, what do I weigh out for the batch, and what does the charge cost per kilogram?
Blend of two charge materials (two scrap grades, a base metal and a master alloy) to reach a target content of an element by alligation (as the mixture blending tool), the masses of each for the batch with a melt loss allowance for the element, and the charge cost per kilogram as a weighted average (as the mixture value tool), checked against your cost limit.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Content of material A | % | Content of the element in material A. |
| Content of material B | % | Content of the element in material B. |
| Target content in the melt | % | Content wanted in the poured metal. |
| Melt loss of the element | % of content | Share of the element lost by oxidation in melting (the charge aims higher to make up for it). |
| Charge mass | kg | Total mass of the charge. |
| Price of A | $/kg | Price of material A. |
| Price of B | $/kg | Price of material B. |
| Highest charge cost | $/kg | Highest average charge cost you accept. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Content of material A
- What it is
- The content of the controlled element (or ingredient) in charge material A, as a share by mass, from the material certificate or analysis.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 7% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- It must differ from material B; the target must lie between the two contents.
What this means: Content of material B
- What it is
- The content of the same element in charge material B, as a share by mass, from its certificate or analysis.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the same element and basis (mass percent) as for material A.
What this means: Target content in the melt
- What it is
- The content of the element you want in the poured metal, from the alloy specification or your aim within its range.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 9% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Moving the target towards one material’s content increases that material’s share.
What this means: Melt loss of the element
- What it is
- The share of the element lost during melting, for example by oxidation, as a percentage of the element’s content. The charge aims higher to make up for it.
- Units and format
- Enter a number in % of content: % of content. The form accepts 0 % of content to 50 % of content. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 % of content as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The charge aim is the target ÷ (1 − loss ÷ 100).
- Get it right
- This is a percent of the content, not percentage points of the melt; use your own melt records.
What this means: Charge mass
- What it is
- The total mass of metal charged into the furnace for this melt.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 10000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 500 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The masses of A and B scale in proportion; the cost per kilogram does not change.
What this means: Price of A
- What it is
- The price paid for each kilogram of material A delivered to the furnace.
- Units and format
- Enter a number in $/kg: money per kilogram. The form accepts $0/kg to $100000/kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $2/kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Price of B
- What it is
- The price paid for each kilogram of material B delivered to the furnace.
- Units and format
- Enter a number in $/kg: money per kilogram. The form accepts $0/kg to $100000/kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $3/kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Highest charge cost
- What it is
- The highest average charge cost per kilogram you accept for this melt, from your costing or quotation.
- Units and format
- Enter a number in $/kg: money per kilogram. The form accepts $0/kg to $100000/kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $2.6/kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Method and formulas
- Charge aim = target ÷ (1 − loss).
- Share of A = (c_B − aim) ÷ (c_B − c_A) by alligation; masses = share × batch (as the mixture blending tool).
- Cost per kilogram = Σ mass × price ÷ batch (as the mixture value tool).
- Example: charge 300 kg of A and 200 kg of B for 9%; the charge costs 2.4 $/kg.
Limitations
- Linear mixing of the element; other elements must be checked the same way.
- Single melt loss figure; actual loss varies with temperature and time.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Make up a furnace charge from two grades
- Dilute a master alloy to a target content
- Compare charge costs for a target chemistry
Who it is for
- Foundry metallurgists
- Furnace operators
- Buyers
What you get
- Charge content aimed for and shares of A and B
- Masses for the batch
- Charge cost per kilogram
Interpreting the result
- If the target is outside the two contents no blend of these two reaches it: add a third material.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 384. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Getting the chemistry right
In Metal Casting by the Numbers
What it covers: Making up a charge that pours to the right composition: blending returns and ingot by alligation, allowing for melt loss, correcting a low melt, and elements that build up with remelting.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
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