Aluminum casting vs magnesium casting: durability and cost comparison
Content Menu
● Aluminum Casting: The Reliable Option for Solid Performance
● Magnesium Casting: Light Contender with Some Challenges
● Side-by-Side Durability: Strength, Wear, and Endurance
● Breaking Down Costs: From Start to Finish
● Stories from Projects: What Worked and Why
Introduction
Fellow engineers in manufacturing, if you’ve spent time around foundries dealing with molten metals shaping into parts, you understand the choices involved in picking materials. We’re looking closely at aluminum casting against magnesium casting here. These metals play big roles in pushing for lighter components in cars, planes, and everyday products, each with upsides that can shift how a project turns out in terms of schedule, spending, and how well it performs.
Consider designing a gearbox housing for an electric car. Magnesium pulls you in with its low density around 1.8 g/cm³ versus aluminum’s 2.7 g/cm³ for cutting weight. Yet questions about toughness arise: Can that magnesium piece stand up to shakes and heat without failing too soon? Costs factor in too—aluminum has long been the steady option, while magnesium prices can jump around.
This draws from actual experiences. One automaker moved to aluminum for brake parts after magnesium tests showed early wear in corrosion trials. Another time, a drone builder cut launch weight by 15% using magnesium enclosures, making the extra initial expense worthwhile over time. We’ll break down the details, pulling from studies and practical cases to help you decide.
You’ll get a solid view on how they compare in staying power—like pull strength, wear from repeated stress, and rust resistance—and in expenses, from base metal costs to tools and final touches. We’ll cover the basics of their traits, uses in different fields, and even mixing them for better results. Settle in; this covers the pours and finishes in depth.
Aluminum Casting: The Reliable Option for Solid Performance
Starting with aluminum, a material that’s held strong in production since early last century. While magnesium grabs attention for being light, aluminum acts as the trusted standby seen in everything from plane bodies to drink containers. Its appeal comes from how alloys work and fit with large-scale methods.
Main Traits and Their Importance
Aluminum casting often uses mixes like A356 or 380, combining pure aluminum with silicon, copper, and a bit of magnesium for good flow and toughness. Density sits at about 2.7 g/cm³, but the key is its strength setup: Pull strengths reach 200-300 MPa after heat steps, with stretch up to 10% allowing some give in designs.
In terms of lasting under stress, aluminum does well against repeated loads. For things like engine blocks with constant pushes, it handles 10^7 rounds at 150 MPa without breaking down. On rust, it forms protective layers naturally, and treatments like anodizing push through 1,000 hours in salt tests. In a heating system job, plain aluminum cases held for five years near the sea, beating what was planned.
It’s not perfect, though. Tears can happen when cooling if flows aren’t right, and bubbles from gases show in heavy areas. Fixes include vacuum pulls in dies or gas removal with argon—common in good operations.
Examples from Real Use
In cars, Ford has cast aluminum heads since the 1990s, such as in EcoBoost motors. A head might weigh 20 kg, half of iron versions, dropping fuel use by 5-7%. From road data, these go 300,000 km with little issue, due to heat processes refining the inner structure against cracks.
For planes, Boeing uses aluminum in gear supports on the 787. Costs and toughness balance tightly: Parts get checked with X-rays for hidden flaws, lasting 50,000 flights. In one review, cracks started only after mimicking 40 years, confirming reliability.
In gadgets, Apple’s laptop frames use 6061-T6 alloy, holding against bumps while staying under 1 kg for smaller sizes. Machining after casting gives a smooth finish without weakening.
Costs for aluminum stay low: Tools handle 100,000+ runs, scrap reuse at 95%. Base prices hover at $2-3/kg, fitting from tests to full output.
Magnesium Casting: Light Contender with Some Challenges
Turning to magnesium, lighter than many expect but needing careful work. Known since the 1800s, it grew after wars for defense, now key for designs focused on mass. Lightness brings issues, though.
Essential Features and Behaviors
Alloys like AZ91D with 9% aluminum and 1% zinc weigh 1.8 g/cm³, cutting 30-35% off compared to aluminum. Pull strengths are 150-250 MPa, yields at 100-200 MPa—good for steady holds but less so in changing forces from lower stiffness (45 GPa vs. 70 GPa).
Toughness varies. It rusts easily near other metals, pitting in damp spots. Coatings like primers help reach 500-800 hours in standard tests. For its mass, fatigue holds up, matching aluminum adjusted for weight at 10^6 cycles under 100 MPa.
Downside is reactivity—burns at 650°C, so gases like SF6 protect during melts, adding steps and fees. Fast cooling in dies makes small grains (10-20 μm), aiding strength, but strains can cause early gives.
Applications and Insights Gained
Cars again: Volkswagen casts magnesium for dash supports in the Golf, at 4 kg vs. 6 kg aluminum. In impacts, they bend to take energy, aiding safety without extra pounds. A study on 50,000 cars found just 2% rust after three years, thanks to treatments.
In planes, Lockheed uses magnesium in F-35 gear boxes, dropping 20% weight while keeping 200-hour checks. Shake tests at 50 Hz showed no breaks to 1,000 hours, but bare areas get watched.
For cameras, GoPro uses AM50 for tough bodies—drops from 2 meters cause no splits, 25% lighter for better hold. Reports note faster rust in salt water for sea uses, leading to mixed designs.
Expenses: Base at $3-5/kg, but quicker sets (20-30% faster) help. Tools last 50,000 runs, half aluminum’s, spreading costs.
Side-by-Side Durability: Strength, Wear, and Endurance
Getting specific, how do they match in holding up? Depends on the setup, but trends show from tests and breakdowns.
Breaking Down Strength and Resilience
Pull strength leans to aluminum at 300 MPa max vs. 250 MPa, but per weight, magnesium leads 20-30%. For a wheel center, 3 kg magnesium equals 5 kg aluminum under 50 kN, easing other parts.
Impact? Aluminum takes 20-30 J in tests, better than 10-15 J, suiting tools like drill casings. DeWalt aluminum gears take 1,000 ft-lb; magnesium wore after 800.
In squeezes, magnesium bends more—key for exact fits. Satellite arms in aluminum avoid 0.5 mm shifts in -50°C to 100°C swings; magnesium needs extras.
Handling Repeated Stress
Curves indicate aluminum at 10^8 cycles under 100 MPa, magnesium 80 MPa—yet weighted, magnesium competes. Toyota aluminum pistons reach 500,000 km; BMW magnesium trials 400,000 with less mass, lowering outputs.
Vibes? Aluminum brackets take 10^7 Hz; magnesium with adds match but need checks.
Fighting Rust in Tough Spots
Magnesium corrodes 0.1-1 mm/year bare in water, aluminum 0.01 mm/year. Near steel, it worsens. Fixes like coats; in valves, treated magnesium beat plain aluminum by 18 months in gases.
Salt? Aluminum lasts 200 hours untreated; magnesium needs covers. Props: Aluminum for 5 years at sea; magnesium in fresh with shields.
For rough areas, aluminum’s edge allows 10-15% more weight. In mild, magnesium’s light boosts effective time.
Breaking Down Costs: From Start to Finish
Finances matter at every stage. Aluminum benefits from volume; magnesium’s specialty raises rates, but let’s look closer.
Base and Supply Costs
Prices: Aluminum $2.2/kg average 2025, magnesium $4.1/kg from heavy processes. For 10,000 cases, aluminum $22k, magnesium $41k. Reuse: Aluminum 95% at $1.5/kg; magnesium 85% at $2.8/kg from mixes.
Swings? Magnesium up 50% in 2023 issues; aluminum stable. Tips: China for cheap aluminum $1.9/kg, Europe for magnesium avoiding fees.
Making and Tool Costs
Cycles: Aluminum 60 seconds, magnesium 40—20% quicker, cutting work time. Tools: Aluminum $50k for 150k runs; magnesium $70k for 80k from hotter flows wearing steel.
Finishes: Aluminum little extra; magnesium barriers $0.50 vs. $0.20 per. Power: Magnesium uses 10% more from gases.
For 2 kg bracket: Aluminum $15 each, magnesium $22 at scale. When? If light saves 3% fuel ($5k per), magnesium returns.
Ongoing and Other Expenses
Initial aluminum lower; long run, magnesium’s cuts add up. In electrics, lighter trays add 10 miles range, up value 5%. Upkeep: Aluminum sturdy, fewer swaps; magnesium coated equals.
Forklift arm: Aluminum $200, 5 years; magnesium $280 but half power, saves in 3.
Stories from Projects: What Worked and Why
Ideas are good, but cases teach. Three examples follow.
Tesla Model 3 base: To aluminum large casts 2020, from magnesium tries. Reason: Better energy take in crashes, $10 less per. Output 1M yearly, big savings.
Medical wheelchairs: AZ91 magnesium frames drop 30% weight, easier move. $15k tool extra back in two years from less material. 50,000 bends no issues.
Plane actuator: Mixed aluminum shell, magnesium inside. $45 vs. $38 all aluminum, 15% lighter for rules. No fails in 2,000 hours.
These guide your choices.
New Mixes and Directions
Combining? Layering aluminum over magnesium grows, blending strengths. Printing for shapes drops 15% cost. Greener agents lower magnesium impact.
Conclusion
Summing up, aluminum and magnesium in casting complement more than compete in cutting weight. Aluminum brings strong lasting and fair prices, fitting high-wear, big runs like motor parts or frames where steady matters over grams. Its history in cars to jets shows: For jobs needing hold in hard spots, aluminum anchors—easy, grows, few surprises.
Magnesium disrupts with big mass drops affecting fuel, control, even rules. It costs more upfront and needs rust watch, but in electrics or carry items, pays off. Think drone cases turning tests to sales, or VW setups opening space. It pushes better covers, plans—parts exceeding expectations.
Choice? Check your needs. For budget, tough basics, aluminum saves 20-30% without short life. For kilo edge? Magnesium, protected, builds gains. From shop tweaks, best mix: Aluminum base, magnesium accents.
This arms you for smarter builds. When picking, think beyond now to future runs. For standards or ounces, these fit—select smart, pour sure, advance.
Frequently Asked Questions
Q1: What’s the main durability concern with magnesium in car applications?
A: Rust from contact with steel—use insulating layers like epoxy to triple life in wet areas.
Q2: How does tool life for aluminum compare to magnesium casting?
A: Aluminum tools go 100,000-150,000 cycles; magnesium 50,000-80,000 from higher heats—add $20k for magnesium swaps.
Q3: Does magnesium work in hot spots like under hoods?
A: To 150-200°C with WE43 types, but aluminum to 250°C; save magnesium for cooler areas for max light.
Q4: When does aluminum save more cost than magnesium?
A: If no big need for light, aluminum trims 20-40% on stuff and steps for over 10k pieces—great for trials.
Q5: Any ways to mix aluminum and magnesium for better results?
A: Co-casting or inserts join aluminum tough with magnesium light, cut 10-15% total while upping hold in varied uses.