Investment Casting Calculators

Pour Weight

Part volume times alloy density gives the casting weight; the gating yield turns that into how much metal has to be melted. Both matter — you are quoted on the first and charged for the second.

Do not know the volume? Any CAD package reports it, and so does the mass properties panel of a STEP file. Gating yield on investment castings usually lands between 40% and 65% — a compact part with one gate is at the top of that, a long thin part fed from a heavy runner at the bottom.

Shrinkage Allowance

Pattern dimension from finished dimension. The factor is a starting point, not an answer: how much a part contracts depends on how much its own geometry restrains it.

Why this is a band and not a number. The percentages most sources publish are VOLUMETRIC solidification shrinkage — the quantity that sizes risers, roughly three times the linear figure. Linear shrinkage is what sizes a die, and it is not a property of the alloy alone: a shape restrained by cores or by its own gating contracts less than a free bar of the same metal. Selecting a family fills in a typical linear starting point; the number that gets cut into the die is the one confirmed on the first article.

Machining Allowance

ISO 8062-3 required machining allowance per machined face, from the raw casting size. A dimension machined on two sides carries it twice.

Grades A to D exist in the standard and are finer than E, but two independent transcriptions of them disagreed, so they are not offered here. A machining allowance that comes out too small is scrap, not rework — an approximate answer would be worse than no answer.

Minimum Wall Thickness

What the shell can actually fill, by process. Below this the section freezes before the far end of the cavity is reached and the casting runs short.

A thin wall is not a single number: the limit is thickness against the distance the metal has to travel through it. A 1.5 mm wall 20 mm long fills; the same wall 200 mm from the gate is a different question, and the answer is usually another gate rather than a thicker wall.

ISO 8062-3 Tolerance

The total tolerance band for a nominal dimension at a given grade. The grades separate at size, not at small features — which is usually the opposite of what people expect.

The figure is the TOTAL band, split either side of nominal unless the drawing says otherwise. Above 630 mm the standard continues; this table stops there because that is where our own capability stops.

Alloy Density

Density for every grade this foundry quotes, and what the same part weighs if it is cast in a different one.

Metric ↔ Imperial

Length, weight, temperature, pressure and surface roughness, in the units a casting drawing actually uses.