Die casting from independent shops
Molten metal is forced under high pressure into a hardened steel die, producing strong, dimensionally stable metal parts with tight repeatability, shot after shot. Once the tooling is paid off, die casting is the lowest per-part cost way to make a metal part at volume, in aluminum, zinc, or magnesium. Upload your part and hear back from independent die casters with tooling and per-part pricing.
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Materials
Die casting alloys
The common die casting alloys and where each fits. Zinc (Zamak) leads for thin walls and fine detail, aluminum for lightweight structural parts, magnesium for the best strength-to-weight. Values are typical ranges; a shop confirms against its process.
| Alloy | Tensile | Hardness | Min wall | Best for |
|---|---|---|---|---|
| Zinc · Zamak 3 | 280 MPa | 82 HB | 0.5 mm | The default zinc: castability, fine detail, plating |
| Zinc · Zamak 5 | 330 MPa | 91 HB | 0.5 mm | More strength and hardness than Zamak 3 |
| Zinc · ZA-8 | 370 MPa | 100 HB | 0.6 mm | Higher-strength zinc, hot-chamber castable |
| Aluminum · A380 | 324 MPa | 80 HB | 1.0 mm | Lightweight structural parts, good all-rounder |
| Aluminum · ADC12 | 310 MPa | 80 HB | 1.0 mm | A380 equivalent common in Asian supply |
| Magnesium · AZ91D | 230 MPa | 63 HB | 1.0 mm | Lightest option, best strength-to-weight |
Zinc alloys run on hot-chamber machines and hold the thinnest walls and tightest detail; aluminum runs cold-chamber; magnesium is the lightest structural choice. Tell the shop the part's loads, weight target, and finish and they recommend the alloy.
Design rules
How to design for Die Casting
Die cast parts live or die by wall design and how cleanly metal flows and fills the die. These rules keep parts free of porosity, sink, and short shots.
| Design rule | Typical spec | Why |
|---|---|---|
| Minimum wall thickness | 0.030 to 0.060 in (alloy-dependent) | Zinc can run thinner than aluminum; thinner walls fill faster but need more precise gating. |
| Draft angle | 1 to 3 degrees per side | Lets the part release cleanly from the die; deeper cavities and textured surfaces need more. |
| Standard tolerance | +/-0.004 in for the first inch, plus roughly +/-0.001 in per additional inch | Tighter features are held with secondary CNC machining after casting. |
| Fillet / corner radius | >= 1x wall thickness | Sharp internal corners restrict metal flow and concentrate stress, driving porosity and die wear. |
| Rib thickness | <= 0.75x adjacent wall | Thicker ribs cool slower than the wall and pull a visible sink mark on the opposite face. |
| Section thickness for porosity | Keep sections under about 0.25 in where possible | Thick sections cool slower and trap gas, causing internal porosity; core out mass where the part allows it. |
| Maximum part size | Alloy- and machine-dependent, typically limited by press locking force | Larger projected area needs a higher-tonnage press to hold the die shut against injection pressure. |
Exact limits depend on the alloy and the part geometry. Send your drawing and a shop tunes gates, wall thickness, and draft to it.
Tooling
Die and process options
The die is the biggest driver of your cost, lead time, and per-part price, and the casting method depends on your alloy. These are the choices die casters weigh, from a single-cavity die to a full production tool.
Casting method
- Hot-chamber die casting
- The melting furnace is built into the machine, so the injection mechanism sits directly in the molten metal. Faster cycles, used for zinc, magnesium, and other low-melting-point alloys.
- Cold-chamber die casting
- Molten metal is ladled into a separate shot sleeve each cycle rather than held in the machine. Slower per cycle, but required for aluminum and other alloys that would corrode a hot-chamber system.
Die layout
- Single-cavity die
- One part per shot. Lowest tooling cost, the right starting point for prototype and low-volume runs.
- Multi-cavity die
- Several identical cavities in one die so each shot produces multiple parts, raising output and lowering per-part cost at volume.
- Family die
- Different parts of one assembly cast together in a single die and shot, useful for matched-set components.
Trim and tool life
- Trim dies
- A separate die or trim press removes flash, runners, and overflow wells after the part comes out of the casting die.
- Tool steel and shot life
- Dies are typically cut from H13 hot-work tool steel. Life ranges roughly from 100,000 shots for a demanding aluminum die up to 1,000,000+ shots for a zinc die, since aluminum runs hotter and wears steel faster.
Process comparison
Die casting vs other processes
Die casting wins on per-part cost and repeatability for metal parts at volume, once its tooling is paid off. When your volume, material, or geometry points elsewhere, here is the better-fit process.
| Process | Best for | Typical volume | Choose it over Die Casting when |
|---|---|---|---|
| Injection Molding | Plastic parts | 1,000 to 1,000,000+ | Your part is plastic, not metal. Injection molding shares the same tooling logic (steel mold, multi-cavity, runner systems) but processes thermoplastics instead of molten metal. |
| Sand Casting | Large or very low-volume metal parts | 1 to 500 | You need a handful of large or one-off metal parts where a hardened die is not worth the tooling spend. Sand casting tooling costs far less, but the process is slower and holds looser tolerances per part. |
| CNC Machining | Low-volume metal / tightest tolerance | 1 to 1,000 | You need a few to a few hundred metal parts with no tooling lead time, or tolerances tighter than as-cast surfaces can hold. Die casting takes over once volume justifies the die. |
| Metal Stamping | Flat or formed sheet metal at volume | High | Your part is flat or sheet-formed rather than a true 3D net shape. Stamping tooling is typically cheaper than a casting die and runs faster for simple sheet geometries. |
Applications
Industries we serve
Die casting shops on OpenSpindle make parts for everything from automotive brackets and housings to consumer electronics enclosures and lighting fixtures.
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Questions
Frequently asked questions
Die casting is a metal casting process where molten metal, typically aluminum, zinc, or magnesium, is forced under high pressure into a hardened steel die (mold). The metal solidifies quickly in the shape of the cavity, producing a strong, dimensionally stable net-shape or near-net-shape part. Because the die is reusable, the process is well suited to producing thousands to millions of identical metal parts once tooling is cut.
Get die casting quotes
Upload your part once and compare tooling and per-part pricing from independent die casting shops for aluminum, zinc, and magnesium.
STEP · STL · IGES · DWG · DXF · PDF · and more
Uploads are secure & confidential