To pick an investment casting manufacturer in India, start with your part, not the foundry's brochure. Check that it pours your alloy, handles your part weight and has held your tolerance class on parts like yours.
Many Indian foundries do investment casting, also called lost-wax casting. They are not interchangeable. One may specialise in small stainless valve parts and have no experience with a 15 kg alloy-steel housing.
Which alloys and sizes does the foundry actually run?
Ask for the alloys poured in the last twelve months, not the full list on the website. Stainless steels, carbon and alloy steels, aluminium and bronze all appear on most capability lists, but each needs its own melting practice and heat treatment.
Part size matters just as much. Investment casting suits small and medium parts, from a few grams up to a few tens of kilograms. A foundry with a small shell room and small furnaces cannot simply scale up to a heavy part.
Ask for the heaviest and the lightest part it makes regularly. If your part sits at either extreme, expect a harder conversation.
What tolerance can an investment caster hold?
Casting tolerances are normally written to ISO 8062, which grades them as casting tolerance classes. Our guide to casting tolerances under ISO 8062 explains how to read them. Investment casting generally sits at the tighter end of the casting processes, but the achievable class depends on part size, shape and the shell system.
Two shell systems are common. Silica sol shells usually give a finer surface and tighter dimensions. Water glass shells are cheaper to run and are often used for larger or less critical parts. Ask which system your parts would run on, and why.
Mark the critical dimensions on your drawing. Anything tighter than the foundry's as-cast capability will need machining, and that should be agreed before the quote, not after the samples.
What should you check inside the foundry?
A visit, or an audit on your behalf, should look at the points below. They show whether the foundry controls the process or only inspects the result.
Our guide to what an investment casting is and when to use one covers the process itself. For the audit side, see what a factory audit should contain.
- A spectrometer on site, with melt chemistry recorded for every heat.
- Wax injection and assembly with controlled temperature and clear pattern records.
- Shell building with controlled slurry and drying conditions.
- In-house heat treatment, or a named outside house with certificates.
- Inspection equipment that matches your drawing, such as a coordinate measuring machine, hardness tester and, where needed, dye penetrant or radiography.
- Material certificates per heat, and marking that links each lot back to a heat.
How should you test a new casting supplier?
Order samples from production tooling, not from a one-off prototype. Ask for a full dimensional report on the first articles, the material certificate and photos of any heat treatment batch.
Then run a small pilot lot before the real order. Many casting problems, such as porosity, shrinkage and shell inclusions, only show up when volumes rise. A pilot lot tells you whether the foundry repeats its own sample.
Also confirm who owns the tooling and where it is kept. A dispute over the wax dies is a common reason buyers get stuck with a supplier.
Next step
If you have a drawing and an alloy in mind, we can shortlist foundries that already make parts of that type, audit them and have samples tested before you commit. Start with a free sourcing review, or read more about machinery sourcing.