Rough big cheap. Fine small precise. Process defines part.

Casting beats machining when: (1) Complex geometry — internal passages, hollow shapes, intricate features. (2) Production volume — tooling amortization over many parts. (3) Cost per part critical — casting often cheaper than machining from billet. (4) Specific materials — some alloys more practical in cast form. Typical break-even vs CNC: 100-500 parts for investment casting, 50-200 parts for sand casting. For one-off or precision parts: CNC usually better.

Yes, very common. Near-net-shape casting reduces CNC work 80-90% vs starting from billet. Standard workflow: cast to approximate shape → CNC machine critical features (bearing bores, mating surfaces, flanges, threaded holes) → finish processing. Combines casting's geometry advantage with CNC's precision. Cost effective for production volumes 500+ parts.

Sand cast raw surface: Ra 6-25 µm, coarse texture visible. Often painted or coated to improve appearance. Machined surfaces applied where needed. Investment cast raw: Ra 1.6-3.2 µm, much smoother — often usable without machining for non-mating surfaces. For cosmetic requirements better than investment cast raw, machining or grinding needed.

Sand casting: ±0.8% to ±2% typical. For 100 mm dimension: ±0.8-2 mm. Cannot hold ±0.1 mm directly — need machining for precision features. Investment casting: ±0.3-0.5%. For 100 mm: ±0.3-0.5 mm. Tighter features possible but cost increases. For precision features, designate them for post-cast machining. Cast and machined hybrid is the practical approach.

Sand casting: virtually any metal — gray iron (standard), ductile iron, steel, bronze, aluminum, zinc, magnesium. Any ferrous alloy, many non-ferrous. Investment casting: most common are carbon steel, stainless (17-4 PH, 316L, Duplex), superalloys (Inconel, Hastelloy), aluminum, bronze. Some specialty alloys difficult to investment cast due to shrinkage characteristics. Cast iron less common in investment casting.

For sand cast prototypes: 3D printed sand molds enable rapid prototyping without physical pattern (1-2 weeks lead time for first parts). For investment cast prototypes: 3D printed wax patterns (SLA resin patterns burn out acceptably) enable rapid prototyping (2-3 weeks). Both methods used to validate casting designs before committing to permanent tooling. We coordinate casting prototypes through partner foundries for both processes.