Cost Accounting Reference for Lost Foam Castings (EPC)

Lost Foam Casting (EPC) is particularly suitable for castings that are difficult to manufacture using conventional methods, such as components with multiple parting surfaces, multiple cores, complex geometries, and intricate internal cavities. Therefore, cost comparisons should be made at an appropriate technical level, rather than simply comparing EPC with the low cost of traditional gray iron casting using a single cupola furnace and clay-bonded sand.

Cost analysis is straightforward and can be divided into two aspects: cost increase factors and cost reduction factors.

The difference between these two determines whether the overall cost increases or decreases after adopting the EPC process.

Original Cost − EPC Cost Reduction Factors + EPC Cost Increase Factors = EPC Total Cost

1. Cost Increase Factors in Lost Foam Casting

The cost increase in EPC mainly comes from two aspects: foam pattern consumption and coating consumption.

Foam pattern consumption is approximately 3,000 g per ton of castings (including gating and risers).

If foam patterns are produced in-house, the cost is about RMB 0.02 per gram, resulting in RMB 60 per ton of castings.

If foam patterns are purchased externally, the cost is RMB 0.03–0.05 per gram, resulting in RMB 90–150 per ton of castings.

Coatings are generally produced in-house.

Refractory aggregate prices range from RMB 500–1,000 per ton.

Other components account for a relatively small proportion.

Assuming RMB 1,000 per ton of dry coating powder, even for thin-walled castings, the coating consumption is only 50–60 kg per ton of castings, corresponding to less than RMB 100.

Therefore, the increased cost of Lost Foam Casting can be estimated as follows (subject to market fluctuations):

In-house foam pattern production: approximately RMB 160 per ton

Purchased foam patterns: approximately RMB 200–250 per ton

2. Cost Reduction Factors in Lost Foam Casting

Dry sand reuse

Dry sand is reused without the need for cores, resulting in minimal consumption and often negligible cost.

Compared with steel casting, more than 1.2 tons of molding sand per ton of castings can be saved.

Compared with iron casting, additional savings include molding materials, shell roasting costs, core-making costs, and core iron costs.

Significantly improved molding efficiency

Molding workers are no longer required, enabling labor savings of more than 40%–60%.

Greatly reduced cleaning and finishing time

Cleaning labor hours can be reduced by up to 90%.

For steel castings, gas consumption for cutting flash and risers is also significantly reduced.

Improved metal yield

Metal yield increases by 10%–30%, especially for ductile iron castings, where riserless pouring can be achieved.

Energy savings through residual heat treatment

Stainless steel, high-manganese steel, and ductile iron castings can utilize residual heat for solution treatment, significantly reducing energy consumption.

No need for wooden patterns for single-piece production

Improved dimensional accuracy

Castings can achieve near-net-shape or minimal machining, reducing casting weight and saving machining time and costs.

Conclusion

Overall, the cost advantage of Lost Foam Casting over traditional processes is undeniable, with a clear reduction in total manufacturing cost when all factors are considered.

However, certain limitations still exist:

1.The level of mechanization is not yet high

2.The casting environment requires further improvement to meet the goals of green casting

3.Further development is needed for non-ferrous metal castings and small-to-medium-sized castings