Lost foam casting starts from a foam pattern, not a two-piece mould. The pattern — one piece or glued clusters — is coated, buried in unbonded sand, and poured with the foam in place; the metal replaces the foam exactly. No parting line, no cores, no draft to design around. That changes what a casting can be, and it is the reason the parts in this category look the way they do.
Without a parting line, geometry stops being negotiated with the mould. Holes and pockets can sit on faces a half-mould could never pull from. Bosses and ribs can point in directions that would need a core in green sand. Bolt bosses arrive as-cast concentric around the hole, which matters when the casting later bolts to a machined face. And because there are no core shifts, internal-to-external wall relationships hold better than most processes at this weight — useful on housings where a misaligned bore means scrap at machining.
On our lost foam line the practical band is roughly 50 to 200 kg per piece — machine bases, pump bodies, guardrail brackets, beam clamps and the heavier agricultural and automotive castings listed in this category. The economics are different from other processes and worth understanding before you quote: foam patterns are moulded per piece, so pattern cost scales with volume instead of sitting as a one-time tooling charge. Small batches pay per-piece for patterns; large batches amortise the pattern tooling. Above the sand line's 50 kg ceiling and below the volumes that justify a heavy sand line, lost foam is often the only route that prices sensibly.
A foam pattern die is cheaper than a full gravity-die or a large sand tooling set, and it is the number we state separately in every lost foam quotation. Pattern life, storage for repeat orders and design-revision cost are all part of that conversation. If your part is still moving in design, say so — lost foam tolerates revision better than most processes because the die is the expensive part, and it changes less.
As-cast surface is good enough for many mounting and wearing faces after shot blasting, but lost foam is not a fine-finish process — where a sealing face matters, we machine it. Coating runs from primer to hot-dip galvanizing to ISO 1461 on outdoor hardware such as guardrail brackets and guy clamps. Machined datums are agreed at quotation so that the features that must align to your assembly come out of the casting already positioned to hold.
The list covers the heavier, more complex castings: machine bases, ductile iron pump bodies, beam clamps, automotive castings and the agricultural families from general farm castings to hammer claws. The dedicated lost foam casting page walks through the process step by step. Some pages you will see here — resin sand, lost wax, steel — sit in this list as general castings guides; if your part belongs to a different moulding route, the Metal Foundry page is the better starting point.
Two cases argue against it. Very thin walls — under about 5 mm — are hard to fill reliably through a foam pattern, and shell moulding will hold the wall better. And pressure-tight parts with large flat sealing faces usually come out of shell or machined green sand cheaper once machining is counted. We will say so at quotation rather than let the process choice discover it at your pressure test.
Lost foam rewards even walls and punishes heat stubbornness. Massive sections next to thin ones want radiused transitions and, sometimes, local foam density changes that we specify. Through-holes are cheap — the foam simply carries the hole — so features that would need cores elsewhere cost nothing extra here, which is why so many bracket and housing families consolidate into one lost foam part. Sharp internal corners should carry a radius; the coating follows the foam, and a tight corner starves it. If your drawing came from a weldment, that is a good starting point: weldments consolidate into lost foam naturally, and the joined plates usually translate into ribs rather than extra mass.
Every heat is checked for chemistry and tensile, foam density is recorded per pattern batch, and first articles ship with a dimensional report. Repeats on an existing pattern run at 30 days; new pattern tooling typically takes 6 to 8 weeks to approved bulk. The foundry has operated to ISO 9001 since 2005.
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Jimo District, Qingdao City, Shandong Province, China
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