Die casting is a high-pressure metal casting process that forces molten metal into a steel mold (die) under high pressure. It produces dimensionally accurate, smooth-surfaced metal parts at high production rates — ideal for automotive, consumer electronics, appliance, and industrial applications.
This guide covers die casting processes, alloys, tooling, design guidelines, and how to evaluate a die casting partner.
The melting pot is integrated into the casting machine. The injection mechanism is submerged in molten metal.
| Parameter | Range |
|---|---|
| Metals | Zinc, magnesium, lead, tin (low melting point) |
| Cycle time | Very fast — 2-10 seconds for small parts |
| Pressure | 10-35 MPa (1,500-5,000 psi) |
| Die life | 500,000-1,000,000+ shots |
Best for: High-volume, small-to-medium zinc/magnesium parts
Molten metal is ladled into the injection chamber (cold chamber) manually or automatically. The chamber is not heated.
| Parameter | Range |
|---|---|
| Metals | Aluminum, magnesium, copper alloys, zinc (large parts) |
| Cycle time | 30-90 seconds (slower due to ladling) |
| Pressure | 30-100 MPa (4,500-14,500 psi) |
| Die life | 100,000-300,000 shots (aluminum wears dies faster) |
Best for: Medium-to-large aluminum parts, high-strength applications
ADC12 (A383) — Most common general-purpose aluminum die cast alloy - Good: Fluidity, pressure tightness, machinability - Tensile strength: 310 MPa - Applications: Automotive parts, electronics housings, power tools
A380 — North American standard, similar to ADC12 - Good: Overall balance of properties - Tensile strength: 320 MPa - Applications: Engine blocks, transmission cases, appliance parts
A360 — Better corrosion resistance than ADC12 - Good: Corrosion resistance, ductility - Applications: Marine parts, food equipment
Zamak 3 — Most common zinc alloy - Good: Excellent castability, dimensional stability - Applications: Hardware, automotive trim, toys
Zamak 5 — Higher hardness and strength - Good: Wear resistance - Applications: Automotive components, gears
ZA-8, ZA-12, ZA-27 — Higher aluminum content, stronger - Good: Higher strength, elevated temperature performance - Applications: Bushings, bearings, heavy-duty hardware
AZ91D — Most common magnesium alloy - Good: Lightest structural metal, excellent EMI shielding - Applications: Electronics, automotive, aerospace
| Component | Material | Hardness |
|---|---|---|
| Die cavity/core | H13 (1.2344) | 44-48 HRC |
| Die cavity/core (premium) | H11, Premium H13 (ESR) | 46-50 HRC |
| Core pins | H13 or Maraging steel | 48-52 HRC |
| Ejector pins | H13 | 48-52 HRC |
| Slide cores | H13 or D2 | 50-52 HRC |
| Part size | Cavity count | Die cost (USD, aluminum) | Die cost (USD, zinc) |
|---|---|---|---|
| Small (<100g) | 2-4 | $15,000-30,000 | $12,000-25,000 |
| Medium (100-500g) | 1-2 | $25,000-60,000 | $20,000-45,000 |
| Large (500g-5kg) | 1 | $50,000-150,000 | $40,000-120,000 |
| Complex (slides, cores) | 1 | $80,000-250,000+ | $60,000-200,000+ |
| Alloy | Recommended | Minimum |
|---|---|---|
| Zinc | 0.8-3.0mm | 0.5mm |
| Aluminum | 1.5-4.0mm | 0.8mm |
| Magnesium | 1.0-3.0mm | 0.6mm |
| Surface | Minimum draft | Recommended draft |
|---|---|---|
| External wall | 0.5° | 1.0-1.5° |
| Internal wall | 1.0° | 1.5-2.0° |
| Core/cavity with texture | 2.0-3.0° | 3.0-5.0° |
| Finish | Description | Typical use |
|---|---|---|
| As-cast | Natural surface from die | Functional parts, hidden surfaces |
| Vibratory finish | Smooth, removed burrs | Deburring, general cosmetic |
| Bead blast | Uniform matte | Cosmetic parts |
| Powder coat | Durable, colored | Outdoor, automotive |
| Chromate (Alodine) | Corrosion protection, conductive | Aerospace, electronics |
| Anodizing | Aluminum only, hard or decorative | Wear resistance, cosmetics |
| Plating (zinc, nickel, chrome) | Zinc: standard; Nickel: functional; Chrome: decorative | Hardware, automotive, decorative |
| Impregnation | Seals porosity | Pressure-tight parts (hydraulic, pneumatic) |
| Feature | Standard (±mm) | Precision (±mm) |
|---|---|---|
| Linear dimensions (up to 25mm) | 0.1 | 0.05 |
| Linear dimensions (25-100mm) | 0.2 | 0.1 |
| Linear dimensions (100-300mm) | 0.35 | 0.15 |
| Die parting line | 0.15 | 0.08 |
| Moving core | 0.2 | 0.1 |
| Flatness (per 100mm) | 0.2 | 0.1 |
| Draft angle (standard) | ±0.5° | ±0.25° |
| Factor | Cost impact | Why |
|---|---|---|
| Alloy choice | Aluminum vs zinc: similar; magnesium: 1.5-2× | Material cost + processing difficulty |
| Part size | Larger = more expensive die + machine | Bigger die, larger machine needed |
| Tolerance | Precision adds 20-40% | Greater tool precision, more quality control |
| Quantity | High volume amortizes tool cost | Die cost spread across parts — typical break-even vs CNC at 2,000-5,000 parts |
| Porosity requirements | X-ray, impregnation add cost | Pressure-tight applications need extra processing |
| Surface finish | Post-casting finishing adds 15-50% | Plating, coating, machining add steps |
| Factor | Die Casting | Investment Casting | CNC Machining | 3D Printing (DMLS) |
|---|---|---|---|---|
| Best volume | 5K-1M+ | 500-10K | 1-1,000 | 1-100 |
| Tolerance | Excellent (±0.1mm) | Good (±0.15mm) | Excellent (±0.025mm) | Fair (±0.2mm) |
| Surface finish | Excellent | Good | Excellent | Fair (needs post-processing) |
| Wall thickness | 0.5-4mm | 1.5-6mm | 0.5mm+ | 0.3mm+ |
| Tooling cost | High ($15K-$250K) | Moderate ($3K-$30K) | Low (CAM only) | None |
| Unit cost at 50K | $0.20-5.00 | $1.00-15.00 | Not practical | Not practical |
| Design freedom | Limited by die | Very good | Good | Excellent |
| Material options | Aluminum, zinc, magnesium | Steel, stainless, copper alloys | All metals | Limited metals |
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