Magnesium Die Casting -The Lightest Structural Metal

Magnesium is the lightest structural metal used in die casting at just 1.74 g/cm³ -35% lighter than aluminum and 78% lighter than zinc. This exceptional weight advantage, combined with excellent machinability, inherent EMI/RFI shielding properties, and good dimensional stability, makes magnesium die casting the preferred choice for applications where mass reduction directly translates to performance improvement.

KastMfg operates dedicated hot-chamber magnesium casting cells with strict fire-prevention protocols including SF6/CO2protective gas cover over the melt, dry sand fire suppression, and trained operators. Our magnesium capability covers AZ91D, AM60B, AM50A, and AS41B alloys across machine tonnages from 160T to 800T.

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Magnesium Alloys We Cast

Alloy	Composition	Tensile (MPa)	Key Properties	Best Applications
AZ91D	Zn-9% Al-1% Zn	230 MPa	Highest strength, best corrosion resistance	General housings, structural covers
AM60B	Zn-6% Al-0.3% Mn	220 MPa	Excellent ductility and impact resistance	Automotive safety-critical structures
AM50A	Zn-5% Al	210 MPa	Improved elongation vs AM60B	Steering wheels, seat frames
AS41B	Zn-4% Al-1% Si	215 MPa	Elevated temperature performance	Powertrain, engine-adjacent components

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Technical Capabilities

Parameter	Specification
Process	Hot-chamber HPDC
Machine tonnage	160T -800T
Density	1.74 g/cm³ (35% lighter than A380 aluminum)
Min wall thickness	0.8 mm
Dimensional tolerance	CT4-CT6 (ISO 8062)
Surface finish (as-cast)	Ra 1.6-2.2 μm
EMI attenuation	60-100 dB at 1 GHz (inherent, no coating required)
Weight range	0.05 kg -8 kg

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Why Magnesium Die Casting?

Lightest structural die casting metal. AZ91D is 35% lighter than equivalent A380 aluminum parts. For automotive and electronics programs where every gram matters -EV range, hand-held device ergonomics, portable equipment fatigue -this weight advantage is significant.

Inherent EMI/RFI shielding. Magnesium alloys naturally attenuate electromagnetic interference at levels of 60-100 dB across 1 GHz frequencies. This shielding is structural -built into the housing itself, requiring no additional metallic coating or gasket. For 5G telecommunications equipment and automotive electronics enclosures, this is a decisive advantage.

Excellent machinability. Magnesium cuts more easily than aluminum, with lower cutting forces, better surface finish, and longer tool life. For programs requiring extensive post-cast CNC machining, magnesium reduces machining cost compared to equivalent aluminum programs.

Dimensional stability. AZ91D has low linear shrinkage (approximately 1.2%) and good dimensional repeatability, maintaining tight tolerances across production volumes.

Recyclability. Magnesium alloys are fully recyclable. Casting gates, runners, and scrap are remelted and reused, contributing to material efficiency and circular economy commitments.

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Magnesium vs Aluminum -When to Choose Magnesium

Decision Factor	Choose Magnesium	Choose Aluminum
Weight	Primary priority	Secondary to cost or performance
EMI shielding	Required inherently	Can be coated
Operating temperature	Below 150°C	Up to 200°C
Corrosion environment	Protected (coating required)	Moderate environments bare
Part size	Small to medium (<8 kg)	Up to 25 kg
Thermal conductivity	Less critical	Important (heat sinks, motors)

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Automotive Applications

Magnesium is well established in automotive interiors and body structure:

• Instrument panel cross-car beams -replacing steel with magnesium saves 3- kg per vehicle
• Seat frames and back panels -AZ91D or AM60B for structural integrity with minimum mass
• Steering wheel armatures -AM50A for ductility during airbag deployment
• Door inner panels -weight reduction in body structure
• Transfer case housings -where operating temperatures and loads are within magnesium's range

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Electronics and Telecommunications

Magnesium's EMI shielding is increasingly specified in:

• Laptop and tablet chassis (ultra-thin, rigid, electromagnetically shielded)
• 5G small cell enclosures and antenna housings
• Router and network equipment chassis
• Camera bodies and handheld device frames
• Drone frames requiring minimum weight and EMI containment

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Safety and Process Compliance

Magnesium in molten form presents fire risk that aluminum does not. KastMfg's magnesium casting operations comply with international safety standards:

• SF6/CO2protective gas cover over all open melt surfaces
• Dedicated dry-sand and D-class fire suppression in magnesium areas
• Trained operators with annual safety certification
• No water or CO2extinguishers in the magnesium zone
• Segregated melt handling and waste disposal

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Frequently Asked Questions

Is magnesium corrosion resistant?

Bare magnesium alloys have moderate corrosion resistance, lower than aluminum. For outdoor or humid environments, chromate conversion coating, e-coating, or powder coating is standard. AZ91D has the best corrosion resistance among common magnesium die casting alloys.

Can magnesium parts be painted or powder coated?

Yes. After appropriate surface preparation (chemical conversion coating), magnesium die castings accept powder coat, liquid paint, and e-coat. Surface preparation is more critical than for aluminum -KastMfg's finishing team follows alloy-specific pre-treatment protocols.

What is the minimum wall thickness for magnesium die casting?

KastMfg reliably achieves 0.8 mm walls in AZ91D in hot-chamber machines. With optimized gating and injection parameters, 0.6 mm is achievable in limited areas of a part.

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Magnesium program inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China