When you hear “casting,” it’s easy to think of a raw metal product priced simply by its weight. But the truth is, castings aren’t commodities. In fact, castings are no more of a commodity than machined, forged, fabricated, or injection molded components.
They’re complex, engineered parts with unique manufacturing challenges that can’t be distilled down to a simple “price per pound” formula. Accordingly, pricing per pound is a gross oversimplification of the true costs involved.
Customized Design and Engineering
Castings are engineered to fulfill a specific function. Unlike bulk commodities, they are designed with precise specifications in mind—from tolerances and wall thicknesses to complex geometries that can’t be achieved through conventional machining practices. Designers and engineers spend significant time modeling, simulating, and testing designs. This R&D investment isn’t captured by just weighing the metal.
Process Complexity and Quality Control
Metal casting involves a series of nuanced steps that affect both quality and cost. The process includes core make and molding, melting, pouring, knockout, heat treat and finishing operations. Each stage requires precision control and expert oversight.
Ensuring that each casting meets stringent quality standards means extensive inspection, non-destructive testing (NDT), and sometimes rework. These quality control measures add to the overall cost far beyond the mere weight of the metal.
Why “Price Per Pound” Doesn’t Tell the Whole Story
The actual metal used is only one part of the expense. Other factors include;
- Labor Costs: Skilled labor for operating foundry equipment and performing inspections.
- Facility and Equipment Investments: The cost of maintaining the operation, including plant and equipment depreciation.
- Energy: Electricity and fuels such as natural gas used in melting, heat treating and processing operations.
- Indirect Costs: Tooling & gating design, sampling, validation and overages to account for sampling and scrap are critical to ensuring a successful casting.
While the raw metal is the primary material input, the casting process itself can lead to material loss.
- Scrap and Rework: Not every casting comes out perfect. Scrap, rejected parts, and rework all contribute to the overall cost.
- Complex Alloys: Some castings require specialized alloys that have higher base costs. Even if the weight is low, the expense of these materials is substantial.
- Kerf Loss: Metal lost in the gating removal and finishing processes can amount to significant cost, especially for exotic and high alloy materials.
Unlike commodities, where price can drop significantly with higher volume purchases, castings are subject to diminishing returns.
- Run Lengths Matter: Due to the fixed costs incurred to set-up and run an order, smaller production volumes can significantly increase the per-unit cost.
- Part Variability: The economies achieved in a high-volume run can’t be applied uniformly across different casting designs. Each casting requires unique resources and process steps in order to manufacture.
The Hidden Value in Castings
A well-engineered casting is designed for optimal performance under specific conditions. High-quality castings can extend the lifespan of machinery or infrastructure, reducing downtime and maintenance costs while reducing the total cost of manufacture.
Modern casting techniques and technology are continually evolving. The advent of 3d sand printing has been a “game changer” and has revolutionized the industry. Casting designs that simply were not possible previously can now be manufactured rather easily using the technology.
Additionally, advances in process simulation and process control allow for tighter tolerances and more complex geometries, offering significant advantages over older methods. Improved techniques often lead to less waste and better energy efficiency, factors that are increasingly important in today’s manufacturing landscape.