What Is Die Casting? Process, Types & Materials

Die casting is a high-pressure metal forming process in which molten metal is injected into a precision-machined steel die (mold) at pressures of 10 to 175 MPa. The metal fills the die cavity in milliseconds, solidifies under continued pressure, and is then ejected as a near-net-shape component -ready for machining, finishing, or direct assembly.

Die casting is one of the most widely used manufacturing processes for metal parts globally, producing billions of components each year across the automotive, electronics, lighting, and industrial machinery sectors.

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Die Casting Meaning -Simple Definition

The term die casting combines two words:

• Die -the hardened steel mold into which metal is injected
• Casting -the process of shaping molten metal in a mold

Together, die casting refers specifically to the high-pressure injection of molten non-ferrous metals into a reusable steel die. It is distinct from sand casting (which uses expendable molds) and investment casting (which uses wax-pattern ceramic molds).

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How Does Die Casting Work? Step-by-Step

Step 1 -Die Preparation

The two halves of the steel die (cover half and ejector half) are closed and clamped under pressure equal to the injection force. The die cavity is sprayed with a release agent to aid ejection and extend die life.

Step 2 -Metal Injection

Molten alloy is ladled or automatically fed into a shot sleeve (cold chamber) or drawn directly from a submerged gooseneck (hot chamber). A hydraulic plunger injects the metal into the die at velocities of 10-100 m/s.

Step 3 -Solidification Under Pressure

The metal fills the cavity in 10-100 milliseconds and solidifies under intensification pressure (up to 100 MPa). This suppresses porosity and fills fine surface detail.

Step 4 -Ejection

After a preset dwell time (0.5- seconds depending on wall thickness and alloy), the die opens and ejector pins push the part out of the cavity.

Step 5 -Trimming

Gates, runners, and overflow wells -required for metal flow control -are removed by a trimming die press or CNC.

Step 6 -Secondary Operations

Parts proceed to CNC machining, heat treatment, surface finishing, and quality inspection as required by the drawing.

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Die Casting Diagram

Molten Metal ->Shot Sleeve ->Injection Plunger ->Die Gate ->Die Cavity
-> Solidification Under Pressure
-> Die Opens ->Ejector Pins ->Part Out
-> Trim ->Inspect ->Secondary Operations

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What Is Die Cast Metal?

Die casting is used exclusively with non-ferrous metals -metals that do not contain significant iron. The most common die cast metals are:

Metal	Common Alloys	Density (g/cm3)	Key Properties
Aluminum	A380, ADC12, A360, A413	2.74	Lightweight, corrosion resistant, thermally conductive
Zinc	Zamak 3, Zamak 5, ZA-8	6.60	Thinnest walls, best surface finish, longest die life
Magnesium	AZ91D, AM60B	1.74	Lightest die cast metal, excellent EMI shielding
Copper (limited)	Brass alloys	8.5	High strength, conductivity -niche applications

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Types of Die Casting

High Pressure Die Casting (HPDC)

The most common form. Metal is injected at 10-75 MPa. Suitable for high-volume, tight-tolerance production. Aluminum, zinc, and magnesium are all processed this way.

Low Pressure Die Casting (LPDC)

Metal is pushed into the die from below at 0.03-1.1 MPa using pressurized gas. Used for large aluminum parts such as automotive wheels where porosity requirements are strict.

Gravity Die Casting

Molten metal flows into the die under gravity alone -no pressure applied. Also called permanent mold casting. Produces parts with less porosity than HPDC but lower production rates and less dimensional precision.

Hot Chamber Die Casting

The injection mechanism is submerged in the melt. Fast, automated, low-pressure -suitable for zinc and other low-melting-point alloys only.

Cold Chamber Die Casting

Metal is ladled separately into a shot sleeve for each cycle. Required for aluminum and magnesium, which would corrode a submerged injection system.

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Die Casting vs Other Casting Methods

Parameter	Die Casting	Sand Casting	Investment Casting
Tolerances	CT4-CT6 (best)	CT11-CT13	CT4-CT6
Surface finish	Ra 1.6-2.2 μm	Ra 6-15 μm	Ra 1.6-2.2 μm
Min wall thickness	0.8-1.2 mm	3- mm	0.5-1.0 mm
Volume sweet spot	10,000-millions	1-10,000	100-10,000
Tooling cost	High	Low	Medium
Unit cost at volume	Very low	High	Medium

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Advantages and Disadvantages of Die Casting

Advantages

• High dimensional accuracy -tolerances to CT4 achievable without post-casting machining
• Excellent surface finish -Ra 1.6-2.2 μm as-cast; suitable for direct coating or plating
• High production rates -cycle times of 20-120 seconds per shot
• Thin walls achievable -0.4 mm in zinc, 0.8 mm in magnesium
• Complex geometry -internal passages, thin ribs, and integral inserts possible
• Long tool life -a well-maintained zinc die can exceed 1,000,000 shots
• Economical at volume -low unit cost offsets tooling investment above ~10,000 pieces/year

Disadvantages

• High tooling cost -H13 steel production tooling costs $5,000-80,000
• Limited to non-ferrous metals -steel and iron cannot be die cast
• Porosity risk -HPDC parts contain some gas porosity that precludes heat treatment in some cases
• Size limitations -parts above ~20 kg are difficult to produce economically
• Wall thickness uniformity required -significant variation causes shrinkage and warpage

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Die Casting Applications

Die casting produces components found in virtually every manufactured product:

• Automotive -engine brackets, gearbox housings, EV motor housings, door handles
• Electronics -heat sinks, connector housings, server chassis, smartphone frames
• Lighting -LED heat sink housings, streetlight enclosures
• Industrial machinery -hydraulic manifolds, pump covers, motor end shields
• Telecommunications -5G enclosures, antenna brackets
• Consumer hardware -power tool housings, furniture fittings, door hardware

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Frequently Asked Questions

What is die casting used for?

Die casting is used to produce high-volume, precision metal parts for industries including automotive, electronics, lighting, industrial machinery, and telecommunications. Any application requiring repeatable, complex metal components in aluminum, zinc, or magnesium is a candidate.

Is die casting the same as injection molding?

No. Injection molding processes thermoplastic or thermoset polymers (plastics). Die casting processes metals. Both use high pressure to fill a mold, but the materials, temperatures, pressures, and resulting properties are entirely different. Die cast parts are metal and significantly stronger, harder, and more thermally conductive than equivalent plastic parts.

What is die cast material?

Die cast material refers to the metal alloy used in the die casting process. Common die cast materials include aluminum alloys (A380, ADC12), zinc alloys (Zamak 3, Zamak 5), and magnesium alloys (AZ91D, AM60B). The term "die cast" also describes the finished part -a "die cast component" is a part produced by the die casting process.

How strong is die cast metal?

Die cast aluminum (A380) has a tensile strength of approximately 317 MPa and yield strength of 159 MPa. Zamak 5 zinc reaches 331 MPa tensile. With heat treatment (T5/T6 on aluminum), tensile strength can reach 350-400 MPa. Die cast parts are significantly stronger than equivalent plastic parts and competitive with many wrought aluminum products.

Related Process Guides

• Die casting process — how the process works end to end
• Types of die casting — HPDC, LPDC, gravity and more
• Die casting steps — step-by-step walkthrough
• Aluminum die casting — the most common die casting alloy family

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KastMfg Manufacturing Co., Ltd. Email: casting@kastdiecast.com | Phone: +86 138 1403 4409 No.6, Rungu Road, Nanjing, China