Aluminum die casting is a high-volume manufacturing process in which molten aluminum is injected into a hardened steel die under pressures of 40 to 100 MPa, solidifying in seconds to produce a near-net-shape part. CharMax Precision runs custom aluminum die casting in A380, ADC12, A360 and A413 alloys on cold chamber machines from 160 to 1,250 tons, for part weights of 20 g to 12 kg.
Aluminum die casting is a high-volume manufacturing process in which molten aluminum is injected into a hardened steel die under pressures of 40 to 100 MPa, solidifying in seconds to produce a near-net-shape part. CharMax Precision runs custom aluminum die casting in A380, ADC12, A360 and A413 alloys on cold chamber machines from 160 to 1,250 tons, for part weights of 20 g to 12 kg.
Because a steel die survives 80,000 to 150,000 shots, the tooling investment is amortised across the production run and the piece price falls sharply with volume. Compared with CNC machining the same geometry from solid billet, die casting typically saves 50 to 80% per part above 5,000 pieces per year, while producing thin walls, integrated ribs and cooling fins that would be slow or impossible to machine.
Every casting program starts with a free engineering review and written DFM report, and can continue through CNC machining after casting, surface finishing, assembly and inspection in the same facility.
| Process | Cold chamber high pressure die casting (HPDC) |
|---|---|
| Alloys | A380, ADC12, A360, A413, aluminum-silicon grades |
| Clamping force | 160 to 1,250 tons |
| Part weight | 20 g to 12 kg per casting |
| Part envelope | Up to 700 × 500 × 300 mm |
| Wall thickness | 1.5 mm typical, 1.0 mm achievable on small parts |
| As-cast tolerance | ±0.1 mm for the first 25 mm |
| Machined tolerance | ±0.02 mm on critical features |
| As-cast surface | Ra 1.6 to 3.2 µm |
| Annual volume | 500 to 500,000+ parts |
| Tooling lead time | 25 to 40 days |
| Production lead time | 15 to 25 days |
Aluminum die casting forces molten aluminum into a reusable steel mold at high pressure and high velocity. Aluminum ingot is melted and held at 660 to 700 °C, a measured dose is ladled into the shot sleeve of a cold chamber machine, and a hydraulic plunger drives the metal through the runner and gate system into the die cavity in 20 to 100 milliseconds. Pressure is held while the part solidifies, the die opens, ejector pins push the casting out, and the cycle repeats.
Aluminum is always cast on cold chamber machines rather than hot chamber machines. Molten aluminum aggressively attacks steel, so the injection system is kept outside the melt and only fills for each individual shot. This is the fundamental equipment difference between aluminum and zinc die casting, and it is why aluminum cycle times are slightly longer.
The result is a near-net-shape part: most features come out of the die at final dimension, and only critical faces, bores and threads need machining afterwards. That combination of speed, geometric complexity and repeatability is what makes die casting the default choice for aluminum parts in production quantities.
At 2.7 g/cm³ aluminum weighs about a third of steel while A380 still reaches 324 MPa tensile strength. For moving assemblies, overhead mounts and anything that ships in volume, that weight saving compounds into lower energy use and freight cost.
The 8-12% silicon content in die casting alloys gives outstanding fluidity and low shrinkage, letting metal fill long, thin flow paths and reproduce fine surface detail before it freezes.
At 96 to 121 W/m·K aluminum conducts heat far better than steel or plastic, so housings can double as heat sinks and cast fins can replace a separate thermal solution.
As a conductive metal, an aluminum casting shields electronics without the conductive paint, foil or plated coatings that a plastic enclosure needs to pass emissions testing.
Aluminum forms a self-limiting oxide layer that resists corrosion in most environments, and low-copper grades such as A360 perform well enough outdoors that many parts need only a cosmetic finish.
Aluminum can be remelted indefinitely without property loss, and runners, overflows and gates are recycled straight back into the melt, which keeps scrap cost low and material efficiency high.
High pressure die casting is the specific casting method behind every part we produce. The process is defined by three controlled variables: injection pressure, metal velocity through the gate, and die thermal balance. Getting all three right is the difference between a sound casting and one riddled with porosity or cold shuts.
Injection pressure between 40 and 100 MPa forces metal into thin sections and holds it against the die wall as it shrinks, which improves density and surface reproduction. Gate velocity of 30 to 50 m/s must be high enough to fill before freezing but controlled enough to avoid excessive air entrainment. Die temperature is held between 180 and 280 °C by internal cooling channels so that solidification proceeds evenly rather than freezing off a thin section prematurely.
We simulate fill and solidification before cutting steel, then log the actual shot profile, die temperature and cycle time for every production batch. When a dimension or a porosity result drifts, that data shows which variable moved.
| Parameter | Typical range | Why it matters |
|---|---|---|
| Melt temperature | 660-700 °C | Too low causes cold shuts, too high increases gas pickup and die wear |
| Injection pressure | 40-100 MPa | Drives metal into thin walls and reduces shrinkage porosity |
| Gate velocity | 30-50 m/s | Must fill before freezing without entraining excess air |
| Die temperature | 180-280 °C | Controls solidification rate, surface finish and die life |
| Cavity fill time | 20-100 ms | Determines whether thin sections fill completely |
| Cycle time | 30-90 s | Sets hourly output and directly affects piece price |
| Tool life | 80,000-150,000 shots | Determines when tooling refurbishment is needed |
Most cost problems in die casting are designed in long before a quote is issued. The geometry decisions below have a bigger effect on piece price and scrap rate than any negotiation over the unit price.
Aim for 2 to 3 mm and keep it consistent. Thick sections solidify last and shrink inward, producing internal porosity and sink marks on the opposite face. Where a section must be heavy, core it out or blend it with a generous radius instead of stepping abruptly.
Provide 1 to 2° of draft on external walls and 2 to 3° on internal walls and cored holes. Insufficient draft causes drag marks, ejector distortion and accelerated die wear, and it is the single most common change we request during DFM review.
Add stiffness with ribs 60 to 80% of the adjoining wall thickness rather than thickening the wall. Ribs raise the section modulus without creating a thermal mass that would trap porosity.
Use fillets of at least 1 mm, and ideally 25 to 50% of the wall thickness, at every internal corner. Sharp internal corners concentrate stress in the part and heat-check the die at exactly that point.
The parting line placement determines which dimensions can be held tightly. Features within one die half hold tighter tolerances than dimensions spanning the parting line, so put your critical relationships on the same side of the die where possible.
Undercuts require slides or lifters, which add tooling cost, lengthen cycle time and create another wear point. Sometimes a slide is genuinely the right answer, but often a small geometry change removes the need entirely.
Leave 0.5 to 1.0 mm of stock on faces that will be machined, and specify cast datum features that a fixture can locate on repeatably. Without defined datums, machining accuracy varies part to part no matter how good the machine is.
Bosses, mounting pads, cable channels, gasket grooves and cooling fins are nearly free once they are in the die. Casting them in is almost always cheaper than machining or assembling them later.
As-cast tolerances hold ±0.1 mm across the first 25 mm of a dimension, widening by roughly ±0.02 mm for every additional 25 mm. Dimensions that cross the parting line or a moving slide carry an additional allowance because they depend on die closure rather than a single cavity surface.
Any feature requiring better than ±0.05 mm, a specific surface roughness, or a controlled geometric relationship should be machined after casting. That is a normal and expected part of the process rather than a failure of it: cast the shape, machine the interfaces.
| Feature | As-cast | After CNC machining |
|---|---|---|
| Linear dimension, first 25 mm | ±0.1 mm | ±0.02 mm |
| Each additional 25 mm | ±0.02 mm | ±0.01 mm |
| Across the parting line | ±0.15 mm | ±0.02 mm |
| Across a moving slide | ±0.2 mm | ±0.02 mm |
| Flatness | 0.1 mm per 100 mm | 0.02 mm per 100 mm |
| Hole diameter | ±0.1 mm | H7 fit achievable |
| Surface roughness | Ra 1.6-3.2 µm | Ra 0.8 µm or better |
| Wall thickness | ±0.15 mm | Not usually machined |
Tolerances follow NADCA precision standards. Tighter values are achievable on specific features with dedicated tooling and inspection, so send your drawing and we will confirm feature by feature.
Die casting becomes economical from roughly 1,000 parts per year and stays the best process into the millions. Tooling is a one-time fixed cost of typically 3,000 to 25,000 USD, so the tooling cost carried by each part falls as volume rises while the piece price stays flat.
Below about 500 pieces a year, CNC machining from billet is usually cheaper because there is no tooling to amortise. Between 500 and 2,000 pieces, simplified or rapid tooling can bring the break-even point down far enough to make casting worthwhile, particularly if the geometry has thin walls or integrated features that would be slow to machine.
We will tell you honestly which side of that line your program falls on. If machining is the better answer for your current volume, our sister CNC operation can produce the parts, and the same design can move to casting later once volume justifies the tooling.
| Annual volume | Recommended process | Reasoning |
|---|---|---|
| 1-100 parts | CNC machining from billet | No tooling cost, fastest path to parts |
| 100-500 parts | CNC machining from billet | Tooling amortisation still outweighs machining time |
| 500-2,000 parts | Rapid or simplified die tooling | Break-even zone, depends heavily on geometry |
| 2,000-10,000 parts | Production die casting | Tooling amortises quickly, clear cost advantage |
| 10,000-100,000 parts | Production die casting, multi-cavity | Multi-cavity dies reduce cost per part further |
| 100,000+ parts | Multi-cavity die casting | Lowest achievable cost per aluminum part |
Every casting is trimmed, deburred and shot blasted to a uniform as-cast appearance as standard. Beyond that, the finish is specified on your drawing and applied in-house.
Casting quality is verified rather than assumed. Alloy chemistry is confirmed by spectrometer against the supplier certificate before casting starts, and every lot stays traceable to its ingot batch.
First article inspection covers every dimension on the drawing and is approved before production release. Production lots are checked to an agreed sampling plan on CMM, with dimensional reports issued per shipment. Where porosity matters structurally we verify by sectioning or X-ray, and pressure-tight parts are leak tested to your specified pressure.
The equipment, controls and finished-part evidence used to deliver this operation in production.
Real parts we have manufactured that involved this capability.
A European industrial pump manufacturer converted a billet-machined housing to A360 die casting to reach 8,000 units a year, holding 6 bar pressure tightness, an H7 bearing bore and a 0.05 mm sealing face.
A collaborative robot manufacturer moved a joint housing from machined prototypes to ADC12 die casting at 12,000 units a year, cutting 180 g per joint while holding ±0.02 mm concentricity between the harmonic drive seat and the encoder bore.
An LED lighting brand replaced a bonded two-piece design, an extruded heat sink adhered to a die cast housing, with a single A413 casting, removing the thermal interface and taking 11 °C off the LED junction temperature at 60,000 units a year.
Die casting pays for itself above roughly 1,000 parts per year. Below that, or while you are still validating a design, CNC machining from billet is usually the faster and cheaper route. CharMax Precision runs a dedicated aluminum CNC machining operation for exactly that work, so you can prototype machined, then move to casting when volume justifies tooling.
Die casting injects molten aluminum into a steel die at 40 to 100 MPa, while gravity casting pours it into a mold under gravity alone. Die casting produces thinner walls, finer detail, better surface finish and much faster cycle times, making it the right choice above roughly 1,000 parts per year. Gravity casting has lower tooling cost and produces less trapped gas, so it suits lower volumes and thick-walled parts that will be heat treated.
1.5 mm is the practical minimum for most parts, and 1.0 mm is achievable on small parts with short flow paths and ADC12 alloy. The real constraint is flow length rather than thickness alone: a 1.5 mm wall that runs 200 mm from the gate is far harder to fill than the same wall running 40 mm. Send the model and our flow simulation will confirm whether your geometry fills before the metal freezes.
Welding die cast aluminum is possible but generally discouraged. The trapped gas that is inherent to high pressure casting expands when heated, producing porous, weak welds and surface blistering. Where a joint is needed, we recommend mechanical fastening into cast bosses, threaded inserts, or adhesive bonding. If a welded joint is unavoidable, specify it early so we can design gating and consider vacuum assist for that area.
Conventional T6 heat treatment is not recommended for high pressure die castings, because the gas entrapped during injection expands at solution temperature and blisters the surface. If your application needs heat-treated properties, the options are a T5 stabilisation treatment, selecting a higher-strength alloy, or moving to a different casting process. We will discuss this during DFM review if your drawing calls for a heat-treated condition.
Porosity is controlled at three stages: melt preparation with degassing and filtration, die design with engineered overflows, vents and gate geometry validated by flow simulation, and process control with logged shot profiles and die temperatures. Where parts must be pressure tight or heavily machined in critical areas, we design vacuum assist or use A360 alloy, and verify with leak testing or X-ray inspection.
A single-cavity production die for a small to medium part typically runs 3,000 to 12,000 USD. Larger parts, multi-cavity dies and tools with multiple slides range from 12,000 to 25,000 USD or more. Tooling is quoted as a one-time charge, remains dedicated to your part, and is stored and maintained at our facility for the life of the program.
A 3D model in STEP, IGES, X_T, SLDPRT or native CAD format, plus a 2D drawing showing critical dimensions, tolerances, surface finish, alloy and any inspection requirements. If you only have a 3D model we can still quote, but a drawing that marks which features are critical to function will get you a more accurate price and prevent misunderstandings later.
There is no rigid minimum once tooling exists, and we regularly run batches of 500 pieces. For new programs, the economics rather than a policy set the floor: below roughly 1,000 annual pieces, we will tell you honestly whether CNC machining from billet would serve you better.
Send your 2D drawing and 3D model. You will get piece pricing, tooling cost, lead time and a written DFM report identifying anything in the geometry that would raise cost or risk quality.