Lost Foam Casting (LFC) is a precision casting process where an expendable EPS is coated and embedded in unbonded sand. When molten metal is poured, the foam is replaced by metal, producing a near-perfect casting with exceptional dimensional accuracy and surface finish.
Unlike conventional sand casting, LFC requires no sand cores, no parting lines, and no draft angles. The result is complex geometry, tight tolerances, and consistent quality — at high volume. This is why Lost Foam is the chosen process for precision structural components like ISO container corner fittings.
Raw EPS beads are pre-expanded to controlled density, then steam-moulded into the exact shape of the corner casting. Our EPS shape moulding machines produce patterns with a cycle time of 5–6 minutes each. The foam pattern is a precise replica of the final metal casting — every aperture, wall thickness, and radius is built into the foam.
Individual foam patterns are glued into casting bunches — clusters arranged to maximise metal yield per box. Our CNC gluing machine ensures precise, repeatable assembly with minimal dimensional variation between batches. Target bunch weight is 125 kg minimum per 1×1×1 m box.
Each assembled pattern cluster is dipped in ceramic slurry — a refractory coating that creates a rigid barrier between the foam and the sand. The coating prevents sand infiltration into the casting surface, directly controlling final surface finish. Coated patterns are dried in our temperature-controlled drying rooms before proceeding.
Coated pattern clusters are placed in our steel mould boxes (1×1×1 m) and surrounded by unbonded silica sand. The boxes are placed on our 3D compaction table which vibrates the sand to achieve uniform, dense packing around every surface of the pattern — critical for dimensional accuracy. Each box holds 7 corner casting patterns.
Our 500KW induction furnace melts steel/iron charge material to the precise temperature required (1,500°C+). Chemistry is verified via spectro analysis before each pour. Liquid metal is poured into the mould box — the EPS foam instantly vaporises and is replaced by metal. Each heat produces 6.16 MT of liquid metal, supporting our 10-heat-per-day production target.
After solidification, boxes are tilted at our hydraulic box tilting station and the casting cluster is separated from sand. Our 20 TPH VLFP sand plant reclaims 98% of the sand — cooling it, removing magnetic particles, screening out fines, and returning it to the mould boxes. A closed-loop system that minimises waste and cost.
Each casting goes through fettling (removal of gates, risers, surface cleaning), followed by dimensional inspection, hardness testing, and visual QC. Accepted castings are shot blasted, primer coated, and packed for dispatch. Full batch documentation — heat records, spectro report, dimensional check — accompanies every order.
| Parameter | Lost Foam (Castora) | Conventional Sand Casting |
|---|---|---|
| Surface Finish | Excellent — smooth, ready for coating | Rough — requires heavy finishing |
| Dimensional Accuracy | High — near-net-shape | Lower — shrinkage and draft variation |
| Sand Cores Required | None — foam is the core | Yes — complex, time-consuming |
| Design Flexibility | High — complex geometry possible | Limited by parting line & draft angles |
| Production Volume | High — automated, consistent | Moderate — labour intensive |
| Material Waste | Minimal — 98% sand reclamation | Higher — cores discarded after use |