How the two processes differ
In die casting, molten metal is forced under high pressure into a hardened steel die. The die is expensive to cut, but it lasts for tens of thousands of cycles and produces near-net-shape parts with thin walls and crisp detail. In sand casting, each part is poured into a one-time mold packed around a reusable pattern. The pattern is cheap, the mold is sacrificial, and the process handles large or low-volume parts that would never justify a steel die.
Neither process is better in the abstract. A bracket you need 200 of and a housing you need 80,000 of point to opposite answers. The sections below take the decision one variable at a time.
Start with annual volume
Volume is the first filter because it sets whether the die ever pays for itself. As a working rule, programs under a few thousand parts per year usually favor sand casting, and programs in the tens of thousands favor die casting. The crossover is not a hard line. It moves with part complexity and material, but it tells you which way to lean before you look at anything else.
- Low volume, under roughly 2,000 parts per year: sand casting almost always wins on total cost.
- Mid volume, 2,000 to 20,000 parts per year: model both. The answer turns on tolerance and finish.
- High volume, over 20,000 parts per year: die casting usually wins once the steel die is amortized.
Tolerance and surface finish
Die casting holds tighter tolerances and produces a smoother as-cast surface, which means fewer secondary machining operations. If your drawing calls out features that must hold a few thousandths of an inch with no follow-on machining, die casting earns its tooling cost. Sand casting runs looser as-cast, so plan for machining stock on any critical feature and a rougher cosmetic surface unless it is finished afterward.
Tooling cost and break-even
A steel die is a real capital line, often the single largest number on a die casting quote, while a sand-casting pattern is a small fraction of that. The honest comparison is total cost across the full annual run, not the per-part price in isolation. Add tooling, per-part cost, and any machining, then divide by the parts you actually plan to order this year.
We were quoting die casting on a 1,500-piece pump bracket out of habit. Modeling it as a sand casting with one machined face cut our first-year cost by more than half and held every critical dimension.
Mechanical engineer, industrial pump sector
Material and part-size limits
Die casting is mostly limited to lower-melting-point alloys such as aluminum and zinc, and to parts that fit the press. Sand casting handles a wider alloy range, including ductile iron and steel, and scales up to large parts that no die press could hold. If your part is big, heavy, or specified in an alloy a die cannot tolerate, sand casting is often the only practical route, independent of volume.
Lead time and what to send us
Standard lead time on a casting program runs 4 to 8 weeks once tooling is approved, with the die or pattern build sitting ahead of that. Mexico production is the faster option for North American buyers, and we act as importer of record and handle customs so the parts land without surprises. Casting work runs out of Monterrey, with additional capacity in Shenzhen for the right programs.
To quote either process accurately, send a CAD model, the annual volume, the alloy if it is fixed, and the dimensions that are critical versus reference. Our engineering team reviews every submission for manufacturability before we quote, and we will tell you which casting process fits the program rather than the one that happens to fill the press.
