Two foundries can quote the same drawing through different casting routes and arrive at very different prices. Investment casting vs sand casting is therefore a comparison of finished-part requirements, not simply the purchase price of a rough casting. A small valve component with several inaccessible features presents a different decision from a large housing whose working faces will be machined anyway.

Let the geometry explain the difference

Investment casting builds a ceramic mold around an expendable pattern. Sand casting forms the cavity in a sand mold, with cores where required. These routes offer different ways to create holes, passages, parting surfaces and local detail. Neither removes the need to consider how liquid metal fills the cavity and how the casting solidifies.

A useful drawing review separates features that must be accurate as cast from those that can be finished later. If a passage cannot be reached by a cutting tool, its cast geometry carries more weight than the finish of an accessible mounting face. Conversely, a generous machining allowance can make a less precise rough form entirely acceptable.

Compare the machining plan before comparing prices

A lower casting price can be offset by more machining stock, additional setups or difficult workholding. Ask both suppliers to quote the same delivery condition. A rough casting and a machined, inspected component are not equivalent offers, even when both use the same alloy designation.

Consider a housing with two precision bearing bores. The bores may need machining under either route. The relevant question becomes whether the remaining geometry justifies investment casting, rather than assuming that a finer cast surface eliminates all secondary work. The datum scheme and clamping surfaces should be reviewed with the manufacturing route.

Order size matters, but it is not a universal cutoff

Tooling investment, pattern maintenance, mold preparation and production yield affect the result. Part size and design stability also change the economics. A frequently revised prototype may favor a different route from an established repeat order, regardless of annual volume.

Request quotations at the quantities you actually expect to release. Include repeat-order quantities and any likely design changes. This gives a more useful comparison than a general claim that one process becomes cheaper above a fixed number of pieces.

Resolve the decision around acceptance

Before releasing tooling, agree the material specification, critical dimensions, machining scope and inspection criteria. Hengke Casting can use the drawing and intended service conditions to discuss a suitable route through the existing product enquiry channels. The strongest choice is the process that consistently delivers an acceptable finished component at the required total cost.