KEVOS® MAKEOS · Fabrication
Casting Pattern Plan (Machining Allowance, Shrinkage, Casting and Pour Weight)
For a block-shaped casting, what pattern dimensions do I make with machining and shrinkage allowances, what will the casting weigh, and how much metal must I pour?
Pattern plan for a rectangular block casting: casting dimensions with machining allowance on the machined faces of each dimension and pattern dimensions enlarged for shrinkage (as the pattern shrinkage tool, applied to length, width and height), casting volume less cores and casting mass, the metal to pour for the casting yield (gates and risers), and a check against the ladle or furnace capacity.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Finished length | mm | Finished length of the part. |
| Machined faces across the length | Number of machined faces across the length (0, 1 or 2). | |
| Finished width | mm | Finished width. |
| Machined faces across the width | Machined faces across the width. | |
| Finished height | mm | Finished height. |
| Machined faces across the height | Machined faces across the height. | |
| Machining allowance per machined face | mm | Machining allowance on each machined face. |
| Shrinkage allowance | mm/m | Pattern-maker’s shrinkage for the metal (from your foundry data). |
| Weight | ||
| Casting metal density | kg/m³ | Density of the cast metal. |
| Volume of cored-out spaces | L | Volume removed by cores. |
| Casting yield (casting ÷ metal poured) | % | Share of the poured metal that ends up in the casting (the rest is gates, risers and runners). |
| Ladle or furnace capacity | kg | Capacity of the ladle or furnace. |
Method and formulas
- Casting dimension = finished + allowance × machined faces; pattern dimension = casting × (1 + shrinkage) (as the pattern shrinkage tool, for each dimension).
- Casting volume = product of casting dimensions − cores; mass = volume × density.
- Metal to pour = casting mass ÷ yield.
- Example: make the pattern 309.18 × 208.14 × 104.07 mm; the casting weighs 46.747 kg and needs 77.912 kg poured.
Limitations
- Rectangular block; draft, fillets and core prints are added by the pattern maker.
- Uniform shrinkage; hindered contraction in complex castings is less.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Make a pattern for a simple block casting
- Estimate metal to melt for a casting
- Check a ladle can pour a casting
Who it is for
- Pattern makers
- Foundry engineers
- Estimators
What you get
- Casting and pattern dimensions
- Casting volume and mass
- Metal to pour and the capacity check
Interpreting the result
- A low yield means heavy risers: better feeding design often saves more metal than trimming allowances.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1414, 1419. Topic reference; no source tables or recommended settings are reproduced.
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