Die Casting Materials

The short answer Die casting's main environmental load is melting metal, not the casting cycle: primary aluminium carries roughly 16 kg CO2e per kilogram, and secondary aluminium needs up to 95 percent less energy than primary smelting. Over 95 percent of process scrap is remelted in house, but VOC release agents and magnesium cover gases are the pieces that need active control. Where the load actually sits Die casting is often described as a green process, and it is, but for reasons that are easy to state imprecisely. The process itself is efficient: high-pressure filling produces a near-net shape in a single shot, the runner and overflow metal goes straight back to the furnace, and the die serves hundreds of thousands of cycles. What carries the footprint is upstream - the primary metal, the electricity for melting it, and the chemistry used to release the part from the die. Melting dominates; the shot itself is brief and the process water runs in a closed loop. The order of magnitude matters when you are setting priorities. Melting and holding molten metal is the largest single energy draw in a foundry, which is why feedstock choice and furnace efficiency dominate any credible emissions reduction plan. Injection, cooling and ejection are comparatively small. Finishing - anodising, plating, powder coating and their pre-treatment lines - is a separate footprint that belongs to the surface treatment supplier rather than to the caster, but it is part of the product's total burden and should be counted. Recycling is the biggest single lever The reason recycling matters so much is that virgin metal carries almost all of the embodied energy. Secondary aluminium requires roughly 5 percent of the energy of primary smelting, which is the same statement as saying recycled material saves up to 95 percent. Secondary zinc shows a similar relationship. That means the single most effective environmental decision on a die-cast part is usually made at the purchasing desk, before any design work begins. Two orders of magnitude of difference: which feedstock you specify outweighs almost everything downstream. Die casting is unusually well suited to taking recycled metal, because the alloys tolerate high recycled content without losing properties, and because the process generates a steady internal scrap stream. Runners, gates, overflows and rejected castings are typically more than 95 percent of the process metal and go directly back into the melt, which is why material utilisation for a well-run cell is high even before external recycling is counted. Aluminium and zinc can both be recycled repeatedly without losing their mechanical properties, so a die-cast part is a stock of future metal rather than a disposal problem. Melting energy and the choice of feedstock Melting point is the reason zinc and aluminium have different footprints at the same output. Zinc alloys melt at roughly 380 to 390 C against about 660 C for aluminium, and a hot-chamber machine holds its metal molten continuously rather than re-melting a charge each cycle, so the energy per kilogram is substantially lower. That is the environmental version of the same advantage that gives zinc its 5 to 20 second cycle times. On the equipment side, the practical measures are unglamorous and well established. Induction and regenerative or recuperative furnaces recover heat that a simple crucible throws away. Keeping furnace doors closed, insulating transfer ladles, preheating the charge with waste heat and holding the metal at the lowest workable temperature all reduce consumption directly. Scheduling melts so the furnace is not held hot through idle shifts usually saves more than any single hardware change. Emissions, lubricants and cover gases Air emissions from die casting fall into three groups, and only one of them is usually regulated tightly. Particulate and metal oxide fume. Zinc in particular produces oxide fume when the melt is exposed to air, and aluminium produces dross and oxide particles. Baghouse filtration, hooding at the furnace and good housekeeping at the die face are the standard controls. Volatile organic compounds from die lubricant. Release agents and lubricants are sprayed onto the die every cycle, and solvent-based products volatilise as VOC. Water-based lubricants cut the load substantially, and fume extraction at the machine handles what remains. VOC matters because it reacts with nitrogen oxides in sunlight to form ground-level ozone. Magnesium cover gases. Magnesium melts oxidise and can ignite, so they are protected with a cover gas. Sulphur hexafluoride is the traditional choice and also the worst possible one on a carbon basis, with a global warming potential of roughly 23,500 times that of carbon dioxide. Alternatives such as sulphur dioxide, HFC-134a at about 1,430 times, or sealed dry-air systems reduce the impact, and semi-solid routes such as thixomolding avoid much of it by operating at lower temperature. Waste streams beyond scrap Four of the six levers are purchasing or design decisions rather than plant equipment. Metal scrap is the waste stream everybody tracks and the one that is easiest to solve. The awkward streams are the others. Spent die steel is heavy but genuinely recyclable as scrap. Dross and salt cake from aluminium melting contain recoverable metal and need proper processing rather than landfill. Hydraulic oils, EDM sludge, machining coolant and used refractory all require licensed disposal. Cooling water should be a closed loop with chillers rather than a once-through flow, both for consumption and for the thermal load returned to the environment. StreamWhere it comes fromBetter practice Runner and overflow metalEvery shotSeparate by alloy and remelt in house Dross and salt cakeAluminium meltingSend to a metal recovery processor Die lubricantDie face every cycleWater-based product plus extraction Magnesium cover gasMelt protectionReplace SF6 with SO2 or HFC-134a Spent die steelEnd of die lifeSell as certified scrap, not landfill Cooling waterDie and machine coolingClosed loop with chillers, no once-through Anodising and plating wasteSurface finishingRegulated effluent treatment and recovery What regulation asks of a die cast part For a component entering Europe, three regimes usually apply and they are about substance content rather than process emissions. The RoHS directive restricts lead, cadmium, mercury, hexavalent chromium and certain flame retardants in electrical and electronic equipment, which is directly relevant because zinc alloys cap lead and cadmium at impurity levels anyway. REACH requires declaration of substances of very high concern anywhere in the article. End-of-life vehicle rules push automotive parts towards recyclability and away from material combinations that cannot be separated. On top of those, customers in regulated sectors increasingly require a material declaration and, where they operate an environmental management system, evidence that their suppliers do too. None of this is exotic for die casting, because the alloys are already clean and single-material. The parts that create trouble are the ones with mixed materials, bonded inserts or coatings that cannot be separated at end of life. Making the trade-off visible in a quotation The honest summary is that die casting's environmental case rests on three things: near-net shape, internal scrap recovery and a genuinely recyclable end product. Those are real, and they are the reason a die-cast part usually has a lower lifetime footprint than the fabricated assembly it replaces. The remaining load is concentrated in primary metal and melting energy, so the questions worth asking a supplier are narrow and answerable: what recycled content can you run, what is your furnace and holding practice, how do you handle dross and spent die steel, and what cover gas do you use on magnesium. We are happy to answer those for your specific part and to advise where a different process carries a lower burden - for example where a lightweighting gain in service outweighs the casting footprint, or where a different material removes a finishing step entirely. See aluminium die casting, surface finishing and plastic injection moulding for the comparable process options. Ask about recycled content and process data for your part Scope and sources. Recycling rates, energy comparisons, emission sources and control measures were compiled in 2026 from a die casting carbon and material efficiency review, a review of die casting environmental impacts covering energy, emissions and waste streams, a die casting machine guide summarising emissions controls and recycling rates and an energy and waste comparison between casting routes. Carbon intensities are indicative global cradle-to-gate averages and vary substantially with regional grid mix, primary versus secondary share, transport distance and alloy. They are planning figures for comparison, not a life-cycle assessment for a specific part, and any regulatory statement should be verified against the current RoHS, REACH and end-of-life vehicle requirements for the destination market.

The short answer Seven grades cover nearly all zinc die casting. Zamak 3 is the workhorse at 283 MPa, Zamak 5 adds copper for 331 MPa, Zamak 2 is the strongest Zamak at 359 MPa and Zamak 7 is the most ductile at 13 percent elongation. ZA-8, ZA-12 and ZA-27 raise aluminium content to 8, 12 and 27 percent for 372, 404 and 426 MPa. The seven grades at a glance Zinc die casting looks like a smaller field than aluminium because it is, and that is an advantage: the grades are well characterised and the differences between them are predictable. Two families matter. The Zamak family is based on about 4 percent aluminium and runs in hot-chamber machines. The ZA family raises aluminium to 8, 12 or 27 percent, which raises strength and hardness and, at the top end, forces a change of process. Composition is the whole story: aluminium and copper move strength and ductility in opposite directions. GradeISO / EN nameStrength MPaElongationTypical use Zamak 3ZnAl4about 28310 percentGeneral hardware, electrical housings, fittings Zamak 5ZnAl4Cu1about 3317 percentGears, levers, load-bearing small components Zamak 2ZnAl4Cu3about 3597 percentBearings, bushing-free pivots, wear parts Zamak 7ZnAl4Niabout 28313 percentThin walls, intricate detail, plating-grade finish ZA-8ZnAl8Cu1about 37210 percentBushings, bearings, small machine elements ZA-12ZnAl12Cu1about 4045 percentStructural brackets and heavy-duty hardware ZA-27ZnAl27Cu2about 4263 percentHighest-strength parts, cast by gravity rather than die casting The Zamak family: 3, 5, 2 and 7 All four contain roughly 3.9 to 4.3 percent aluminium, which is the near-eutectic composition where the alloy is most castable. What separates them is copper and, for Zamak 7, nickel. Zamak 3 is the default and the most widely used zinc die casting alloy in the world. It has the best combination of castability, dimensional stability and cost, machines and plates well, and holds about 10 percent elongation, which is enough ductility for most hardware. If a drawing does not name a grade, the quote is probably Zamak 3. Zamak 5 adds roughly 0.7 to 1.1 percent copper, which lifts tensile strength from about 283 to 331 MPa and improves hardness, creep resistance and wear behaviour. The price is a little of the ductility and a slightly narrower process window, which is why it is specified for gears, levers and parts that carry load rather than for general housings. Zamak 2 raises copper to roughly 2.7 to 3.3 percent and is the strongest and hardest of the Zamak family at about 359 MPa. Its dimensional stability is slightly lower than Zamak 3, so it is reserved for bearings, wear surfaces and small high-load parts where strength matters more than long-term stability. Zamak 7 is the ductility grade. It keeps copper at the impurity level but adds a small nickel content and tightens the magnesium range, which produces about 13 percent elongation, the best in the family. That combination makes it the choice for thin, intricate, impact-resistant parts and for components that must take a high-quality plated finish. The ZA family: 8, 12 and 27 The ZA alloys trade castability for strength by raising aluminium. ZA-8 at about 8 percent is the most useful of the three in die casting: it runs hot chamber like the Zamak grades, reaches roughly 372 MPa and offers excellent bearing characteristics, so it is often used for bushings and small machine elements that would otherwise need a pressed insert. ZA-12 at about 12 percent aluminium reaches roughly 404 MPa and is used for structural and heavy-duty parts, though it needs cold-chamber processing. ZA-27, at roughly 27 percent aluminium, is the strongest zinc casting alloy at about 426 MPa with the lowest density of the family, but its aluminium content makes it unsuitable for pressure die casting in practice and it is normally gravity or sand cast. Strength doubles across the range, and ductility falls by a factor of four at the same time. Purity limits matter more than the headline numbers The composition table hides the specification that actually governs whether zinc parts survive. Every die casting grade requires high-purity zinc and caps three elements tightly: lead at 0.005 percent maximum, tin at 0.003 and cadmium at 0.004. Those limits exist for a specific failure mode. Above them, the alloy becomes susceptible to intergranular corrosion, and a part that passes inspection today can swell, crack or lose strength months into service, particularly in warm humid conditions. The practical consequence is that grade substitution between suppliers is not as safe as it looks. A Zamak 3 ingot made from high-purity zinc to the published limits is not interchangeable with a generic zinc alloy of similar appearance. Ask for the ingot specification and the certificate with each heat, especially where parts are safety-related, exposed to moisture or expected to last decades. How to pick a grade in four questions Load first, finish last: ductility and strength trade off, so decide which one the part actually needs. What is the load? Static loads and general service point to Zamak 3. Wear, pivoting or gear contact points to Zamak 5 or Zamak 2. Impact or flexing points to Zamak 7, because elongation is what absorbs energy. How thin is the wall? Below about 0.8 mm the answer is almost always Zamak 7 for ductility or Zamak 3 for general work; the higher-aluminium ZA grades do not fill as easily. Which chamber is available? Zamak grades and ZA-8 run hot chamber with 5 to 20 second cycles. ZA-12 and ZA-27 need cold chamber, which is slower and costs more per part. What finish is required? Bright chrome and nickel plating favour Zamak 3 or Zamak 7. ZA-27 will plate but its high aluminium content makes bright finishing harder, and it is rarely chosen for decorative work. Where a grade change is not free Strength and ductility trade against each other. Moving up the table from Zamak 3 to ZA-27 roughly doubles tensile strength but cuts elongation from 10 percent to about 3. A part redesigned for the stronger grade without checking impact loading can fail in a different way. Hot-chamber capability is lost above ZA-8. ZA-12 and ZA-27 need cold-chamber machines, which removes the cycle-time and energy advantage that justified zinc in the first place. Dimensional stability varies. Zamak 3 is the most dimensionally stable; Zamak 2 and the ZA grades grow slightly as the alloy ages, which matters on long close-tolerance assemblies. Service temperature is capped near 100 C for the whole family, so a high-strength grade does not make zinc suitable for hot applications. Grade does not change that physics. Purity is not negotiable. A cheaper ingot outside the lead, tin and cadmium limits will eventually show up as corrosion failures rather than as a casting defect. Getting the grade right in the quotation Tell us what the part does rather than only what alloy you have in mind. The load path, the operating temperature and environment, the wall thickness, whether the part is plated and the annual volume are enough to select between Zamak 3, 5, 2 and 7 and the ZA grades, and where two grades both work we will quote both so the strength you gain and the ductility you give up are visible on the page. Related processes are aluminium die casting, surface finishing for plating and coating, and laser cutting or metal stamping where a formed sheet part is the better answer. Send a drawing for zinc alloy selection Scope and sources. Composition ranges and mechanical properties were compiled in 2026 from an ASTM B240 based alloy and property table for Zamak and ZA grades, a die casting zinc alloy composition and property reference and a zinc alloy selection guide with typical applications. Values are as-cast typical figures: tensile strength, hardness and elongation move with section thickness, gate design, porosity and cooling rate, so treat them as planning bands and confirm against a first-article inspection. Purity limits and designations should be confirmed against the current ASTM B240 or EN 1774 edition for the grade in question.

The short answer Zinc alloys run in hot-chamber machines at 380 to 390 C, so they cycle in 5 to 20 seconds, fill walls down to 0.4 mm and hold tolerances around plus or minus 0.05 mm. Dies last 500,000 to a million shots. The trade is weight at 6.6 g/cm3 and a service ceiling near 100 C. Seven advantages, ranked by what they save Zinc is often overlooked because aluminium is the default choice, but zinc's advantages are not marginal - they are structural consequences of running 280 degrees cooler. Tool life several times longer than aluminium. The lower melt temperature means far less thermal shock and heat checking in the die. A zinc die commonly delivers 500,000 to more than a million shots against roughly 200,000 to 350,000 for aluminium, which is the largest single tooling saving available in a precision casting program. Thin walls down to about 0.4 mm. Exceptional fluidity lets zinc fill fine detail that aluminium cannot reach, so a smaller, lighter part can carry the same function without the weight penalty of a solid design. Tight, repeatable tolerances. Zinc holds around plus or minus 0.05 mm on many cast features and behaves more like a machined part, so secondary machining is often eliminated entirely. Fast hot-chamber cycles. 5 to 20 seconds per shot against 20 to 90 seconds for aluminium, with the metal held molten and injected by plunger rather than ladled shot by shot. Strength and hardness that beat the aluminium grades. Zamak 3 at about 283 MPa is comparable; Zamak 5 reaches roughly 331 MPa and the ZA alloys go higher still, while zinc's bearing and wear behaviour lets small bushes be cast in place instead of pressed in. A smoother skin for plating. Zinc is less prone to the surface pits that come from higher casting temperatures, so the chrome or nickel finish that amplifies every defect on an aluminium part is easier and cheaper to achieve. Lower melting energy and full recycling. Melting zinc takes far less energy per kilogram than melting aluminium, and all process scrap returns to the melt. The energy advantage widens further when recycled feedstock is specified. Thin walls and tight tolerances The minimum wall you can cast is a fluidity question, and fluidity tracks the melting point. Zinc fills from about 0.4 mm where the flow path is short and the geometry is well gated, comfortably reaching 1 mm in production parts. Aluminium in practice reaches about 1.0 to 1.5 mm only over a limited flow length, and thicker walls are the safe design. Wall capability is set by fluidity, and fluidity by how hot the melt has to be. Tolerance follows the same root cause. Because the melt starts cooler and the die distorts less between shots, zinc holds about plus or minus 0.05 mm on many as-cast features and around plus or minus 0.13 mm on the more demanding ones. Careful designers use that to design out machining: this is sometimes called zero-machining manufacturing, and it is one of the clearest cost advantages zinc has over either aluminium or plastics. Die life is the largest single saving A die is capital, and its life is amortised into every part. Thermal shock is what kills a die through heat checking, and thermal shock is a function of how far the die surface must heat and cool each cycle. Reducing the melt temperature from 660 C to 385 C removes most of that load, which is why zinc dies commonly run two to five times longer than the aluminium equivalent and never need to be replaced inside a typical program. Same capital figure, several times the number of parts: the tooling charge per part falls directly. Zinc against aluminium, metric by metric The comparison is easiest on the numbers, because most of the disagreement between buyers and designers is really about which row matters most. Zinc wins four rows, aluminium wins two, and the two it wins are weight and heat. DecisionChoose zinc whenChoose aluminium when Part size and weightThe part is small and precision matters more than massThe part is large or weight is on the specification Wall thicknessWalls below about 1 mm are neededWalls are 1.5 mm or thicker Service temperatureOperating temperature stays below about 100 CThe part sees engine or exhaust heat Coating and finishBright chrome, nickel or decorative plating is requiredAnodising or a structural powder coat is enough VolumeVery high volume, where die life dominates the business caseMedium volume, where weight and service heat dominate Bearing and wear featuresBushes and wear surfaces can be cast in placeSeparate inserts are acceptable Finish and plating quality Zinc alloys are the decorative casting material, and the reason is metallurgical rather than cosmetic. A cooler melt produces a smoother, less porous skin, and a smoother skin is what takes a bright finish without the buffing that aluminium usually needs first. Zinc parts polish, plate, powder coat and paint readily, which is why lock hardware, sanitary fittings, camera bodies, zipper pulls and automotive trim are usually Zamak rather than aluminium. The same properties make zinc a natural choice for shielding and grounding components, with thermal conductivity around 105 to 126 W/m.K and electrical conductivity of roughly 25 to 30 percent IACS. The limits: heat, weight and ductility Service temperature is the hard ceiling. Zinc alloys lose strength and creep above roughly 95 to 100 C, so anything in an engine bay, near a heat source or under sustained load at temperature should not be zinc. Weight is the standing penalty. At about 6.6 g/cm3 zinc is roughly two and a half times as dense as aluminium, so it makes sense for small dense parts and rarely for large ones. Ductility is lower than aluminium. Elongation of roughly 7 to 13 percent for the Zamak grades sounds adequate until an application needs significant deformation or high-impact resistance, where aluminium or a ductile casting alloy is safer. Purity is not optional. Zinc alloys specify lead at 0.005 percent maximum, tin at 0.003 and cadmium at 0.004. Contamination above those limits causes intergranular corrosion and dimensional change that appears months after the parts are in service. Porosity and blistering need process control. Zinc is more prone than aluminium to surface blistering if the melt, the die temperature or the lubricant are wrong, so the process window is narrower than the low casting temperature suggests. The alloy range is smaller. There are seven realistic zinc die casting grades against a much wider aluminium menu, so there is less freedom to fine-tune properties. Deciding between zinc and aluminium The rule we use is short: if the part is small, needs thin walls, tight tolerances or a bright plated finish, and stays below about 100 C, zinc is usually cheaper in total despite the higher metal price, because the die lasts several times longer and secondary operations disappear. If it is large, weight-sensitive or runs hot, aluminium wins. Send the drawing with the service temperature, the annual volume and the cosmetic requirement, and we will quote both families where both are viable so the comparison is on paper rather than in principle. Related processes are aluminium die casting, surface finishing for plating and coating options, and metal stamping where a formed sheet part is the cheaper answer. Ask us to compare zinc and aluminium for your part Scope and sources. Property values, cycle times, wall limits and tool-life ranges were compiled in 2026 from a zinc die casting capability review covering fluidity, tool life and tolerance grades, a direct comparison of zinc and aluminium die casting, a summary of zinc alloy advantages over aluminium and a zinc die casting guide covering process limits and disadvantages. Tool life and tolerance depend heavily on part geometry, gating, thermal control and maintenance practice, so treat every range here as a planning band for budgeting rather than a guarantee. Confirm against a DFM review and first-article inspection before releasing a program.

The short answer Aluminum die casting wins on volume economics: 15 to 60 second cycles, H13 dies that last 100,000 to 500,000 shots, and near-net shapes that cut material waste by 60 to 80 percent against machining. Those three together make it the lowest total-cost route above about 5,000 parts a year, and the only one that also casts features instead of assembling them. Speed is the first benefit, and it is structural Every other casting route is slow, and the gap is not marginal. Sand casting a housing takes minutes per part and needs machining stock on every surface. Gravity and permanent mould casting sits in the middle. High-pressure die casting injects the melt in milliseconds and completes a shot in 15 to 60 seconds for most small and medium parts, which is why a single cell can produce 100 to 500 shots an hour and 50,000 to 500,000 parts a year per cavity once the die is qualified. Only high-pressure die casting fits a takt time measured in tens of seconds. That speed has a second effect that is easy to miss: because the die is steel and the cycle is short, the process supports statistical process control. Once a die is qualified the part-to-part variation stays small across millions of shots, which is what allows a casting to be treated as a controlled component in an automotive or medical supply chain rather than as a foundry lot to be inspected in. Cost per part falls with volume, and the shape of the curve matters Die casting is expensive to start and cheap to run. Tooling for aluminium runs from roughly USD 8,000 to USD 80,000 or more depending on size, cavity count and complexity, and lead time is typically 5 to 8 weeks, with bridge tooling cutting that to 3 to 5 weeks for a few hundred to a couple of thousand near-production parts. After that the unit cost is dominated by metal, cycle time and secondary operations, and it keeps falling as the tool amortises. The route should be chosen by volume, before alloy and before design detail. BenefitTypical valueWhat it replaces Cycle time15 - 60 seconds per shotMinutes per part in sand or gravity casting Throughput100 - 500 shots per hourBatch scheduling with work in progress Material waste60 - 80 percent less than machiningSwarf, billet stock and handling Total component cost20 - 40 percent below fabricated assembliesStampings plus welding plus fasteners As-cast toleranceplus or minus 0.1 to 0.25 mmMachining stock on non-critical faces Machined toleranceplus or minus 0.02 to 0.05 mmA separate machining supplier As-cast surfaceRa 0.8 - 1.6 umMilling and polishing passed on from a casting Die life in H13100,000 - 500,000 shotsTooling replaced within a single program Machining stock needed0.25 mm or less per surface0.75 mm on a sand casting Break-even against machiningabout 5,000 parts a yearMachining from billet at any volume Net shape removes whole assemblies, not just operations The most underused advantage is consolidation. Ribs, bosses, mounting pads, cored holes, threads and internal channels are formed in a single shot, so a transmission housing that might otherwise need a dozen stampings and forty welds becomes one part. That is not only a labour saving: joints are where stiffness, leak paths and warranty claims live, and removing them changes the reliability of the assembly as well as its cost. Consistency you can plan a production line around Repeatability is what makes die casting a manufacturing process rather than a craft. As-cast linear tolerance of roughly plus or minus 0.1 mm under 25 mm, widening to plus or minus 0.25 mm over 250 mm, lets most non-critical features stay as-cast, and only bearing bores, sealing faces and cosmetic surfaces need cutting. Surface quality follows the same logic: an as-cast Ra of 0.8 to 1.6 um is fine for anything hidden, and bead blasting or a conversion coating is enough for most visible aluminium parts. Die life is what funds all of this. H13 tooling typically delivers 100,000 to 500,000 shots before refurbishment, and each shot is one part or several, so the tooling charge per part becomes small in exactly the volume bands where the process competes. Where the cost is really committed Roughly 70 percent of a component's lifetime cost is decided during design, when only about 8 percent of the cost has been spent. That is why the four decisions below matter more than any supplier negotiation. Wall, draft, gate and machining allowance decide the price before the die is cut. Wall thickness. Target 2 to 3 mm nominal for aluminium and keep variation across the part inside a 1:3 ratio. Solidification time scales with the square of section thickness, so reducing a 4 mm wall to 2.8 mm roughly halves cooling time and removes around 25 percent of the mass. Draft and parting line. About 1 to 2 degrees external and 2 to 3 degrees internal, because the casting shrinks onto the core as it cools. Placing the parting line where flash cannot land on a cosmetic face costs nothing at design stage and is expensive later. Gates and porosity control. Metal enters at 30 to 50 m/s, so air is entrained unless the gates and vents are designed for it. Vacuum assistance reduces internal porosity below about 0.1 percent where pressure tightness or a machined sealing face demands it. Machining allowance. Every face you plan to cut is another chance to expose porosity that would otherwise have stayed harmlessly under the skin. Cut what the function needs and leave the rest as-cast. When aluminium die casting is the wrong answer Low volume cannot carry the tooling. Below roughly 3,000 to 5,000 parts a year, machining from billet, sand casting or a bridge tool is usually cheaper overall. The break-even is a calculation, not a rule of thumb, and it moves with part size. Standard castings cannot be solution heat treated. Entrained gas blisters the surface above 500 C. Use T5, or pay for vacuum-assisted high-integrity casting if the load case really needs more. Thick sections are the hardest thing to cast. Above about 8 mm the interior is likely to shrink into porosity. Where mass is genuinely needed, core the section out and add ribs instead. Wrought alloys are not an option. A drawing that specifies 6061-T6 is a machining specification. Die casting needs a casting alloy such as A380 or ADC12. Very thin walls with long flow paths favour zinc. Aluminium reaches about 1.0 to 1.5 mm only over a limited flow length. If the part is small and needs 0.5 mm walls, the material is probably wrong. Tight bores and seal faces still need machining. The as-cast tolerance will not hold a bearing fit, so plan the secondary operation into both the design and the price. Getting a real number for your volume A useful quotation shows the break-even rather than asserting one. Send the drawing or STEP file with the annual volume and expected program life, the load case and environment, any pressure-tightness requirement and the surfaces that must remain as-cast, and we will return DFM feedback on walls, draft, parting line and porosity risk alongside the price at two volumes. We cast aluminium and zinc and machine critical features in house, and the adjacent processes are aluminium die casting, surface finishing and plastic injection moulding where a polymer can do the job. Send a part for a volume and break-even quotation Scope and sources. Cycle times, throughput, tooling ranges, tolerance bands and break-even points were compiled in 2026 from an overview of aluminium die casting benefits and process economics, a summary of aluminium die casting advantages with cycle and tool-life figures, a high-volume manufacturing review comparing die casting with sand, gravity and plastic routes and a die casting design-rule set covering wall, draft, fillet and boss limits. Values vary with part geometry, alloy, cavity count, machine tonnage and program length, so the figures here are planning bands for budgeting rather than quotations. Confirm them against a DFM review and first-article inspection before committing to a program.

The short answer Aluminum die casting is dominated by four or five Al-Si alloys. A380 and its equivalents ADC12 and ADC10 cover general housings and brackets, A383 fills large thin walls, A360 handles corrosion and pressure tightness, A413 suits leak-critical manifolds and B390 is reserved for wear surfaces. Silicon controls fluidity; copper controls strength and corrosion. Die casting alloys are a separate family from wrought aluminium The aluminium in a die casting is not the aluminium in an extrusion or a machined block, and the difference is deliberate. Wrought alloys such as 6061 and 6063 contain only about 0.4 to 0.8 percent silicon and have a wide freezing range. Poured into a steel die at high velocity they hot-tear and stick, which is why a drawing that specifies 6061-T6 belongs in machining or fabrication rather than in a casting quotation. Casting alloys raise silicon to 7 to 13 percent, sometimes 17, which lowers the melting range, sharpens the freezing interval and makes the melt flow far enough to fill thin ribs before it sets. The second structural point is that aluminium must run in a cold-chamber machine. At around 690 C the melt dissolves iron out of a submerged gooseneck, so hot-chamber injection belongs to zinc and magnesium only. Everything below therefore assumes a cold chamber, a die in H13 tool steel and a wall in the 1 to 4 mm range. The grades you will actually be quoted Composition is the fastest way to tell the grades apart, because every element is there for a reason. Silicon buys fluidity and wear resistance. Copper buys strength and hardness and costs corrosion resistance and bright anodising. Iron, held around 0.6 to 1.0 percent, stops the casting soldering itself to the die. Magnesium refines the structure and, at higher levels, makes the alloy heat-treatable. Five grades cover the great majority of aluminium die casting work. GradeRoughly equivalent toBest forWatch out for A380EN AC-46000, LM24Brackets, gearbox covers, general housingsHigh copper means anodising goes mottled grey ADC12JIS H 5302, close to A383Thin-wall, intricate castingsSilicon range is wide, so verify each heat A383EN AC-46500Large thin covers needing good fillSlightly softer and less strong than A380 A360EN AC-43400Marine, outdoor and pressure-tight partsFills harder, cycles slower, costs more A413EN AC-44300, LM6Hydraulic bodies and leak-critical manifoldsPoorest machinability of the group A356EN AC-42100, LM25Structural parts that must be heat treatedNot a high-pressure die casting grade in practice B390SAE B390Bearing surfaces, pump and engine partsVery abrasive to the die, so tool life drops Silicon, copper and iron: what each element buys Reading a certificate of analysis is the skill that separates buyers who get what they asked for from buyers who get what was in the furnace. Silicon is the fluidity budget, and increasing it from 8 to 12 percent is what allows a 1.2 mm wall to fill over a long flow path. The cost is machinability and die wear, which is why a 17 percent silicon alloy such as B390 machines like a different material altogether and shortens die life. Copper is the strength budget: A380 carries roughly 3 percent and A360 less than 0.6 percent, and that single difference is what makes A360 the choice for anything that lives outdoors. Silicon is the fluidity budget, and it is spent on machinability and die life. Two trace elements quietly decide whether a run goes well. Iron is a nuisance in most metallurgy, but in die casting it reduces die soldering and raises hot strength, which is why specifications permit it up to roughly 1.0 to 1.3 percent. Zinc is the opposite: it improves castability but above about 1.5 percent it promotes hot shortness, so A380 caps zinc at about 3 percent and a contaminated melt becomes brittle. Both are worth checking heat by heat rather than relying on a generic data sheet. How to pick a grade in four steps The order matters, because each step eliminates options that the next step cannot rescue. Process first, finish last: reversing the order is how alloy changes get forced after the die is cut. Apply the process limits. High-pressure die casting only, which means the alloy must come from the casting family. Confirm the wall is between about 1.0 and 4 mm and that the part fits the machine. Check the filling requirement. Long, thin flow paths need 10 to 12 percent silicon. Compact thick parts do not, and paying for fluidity that is not needed costs machining time and die life. Check the service conditions. Salt spray or outdoor exposure pushes you to the low-copper grades. Wear surfaces push you towards high silicon. Anything that must hold pressure pushes you towards a more eutectic alloy. Decide the finish last. If the part must be bright anodised, copper is the enemy and A360 or A413 is the answer. If it will be powder coated, plated or left as-cast, copper is free to do its job. Where the grades are not interchangeable 6061 and 6063 cannot be die cast. Their low silicon content and wide freezing range produce hot tears in a steel die. If the drawing says 6061-T6, the part needs machining or fabrication, not a casting quotation. A380 will not anodise bright. Its roughly 3 percent copper produces a mottled dark grey film. Buyers expecting the appearance of anodised 6061 are reliably disappointed. Specify A360 or A413 at design stage, because changing alloy after tooling is cut can require re-engineering the gates. A356 belongs to permanent mould, not pressure die casting. It is the grade for heat-treatable structural castings, poured at lower velocity so that it can take a T6 treatment without blistering. Standard die castings cannot be solution treated. Gas entrained at 30 to 50 m/s gate velocity expands above 500 C and blisters the surface. Use T5, or specify vacuum-assisted casting where the load case genuinely needs more strength. Secondary operations still apply. As-cast linear tolerance is around plus or minus 0.13 mm on good features; bores, sealing faces and bearing fits are machined afterwards to plus or minus 0.02 to 0.05 mm. Designations, equivalents and certificates The same alloy arrives under at least four naming systems, and it is worth recognising them before comparing quotations. The American system uses AA numbers such as A380 and A383. The Japanese JIS system uses ADC10 and ADC12. Europe uses EN AC numbers such as EN AC-46000 and EN AC-43400. Older British and Commonwealth drawings use LM designations, where LM24 is close to A380 and LM6 is close to A413. Chinese supply usually quotes GB YL113. None of these is a lesser grade, but the permitted ranges differ slightly between them, so a quotation that says only ADC12 is not the same as one that names the standard. Ask for a spectrographic certificate per heat rather than a generic data sheet. The elements that change how the melt behaves are exactly the ones that drift: silicon shifts fluidity, copper shifts strength, and iron and zinc shift both soldering behaviour and machinability. A generic sheet tells you what the alloy should be, not what was poured. How we choose the alloy for a part We cast aluminium and zinc and machine the critical features in house, so the recommendation follows the part rather than the ingot we happen to have in stock. Send the STEP file or drawing with the load case, the environment, the annual volume and any cosmetic requirement, and we will come back with a grade, the wall and tolerance expectations, the draft and gate position, and DFM feedback on where porosity is likely. Where two grades are viable we will price both, because the cheaper alloy is not always the cheaper part once machining and finishing are counted. See aluminium die casting, surface finishing for the anodising and coating options and metal stamping for the sheet-metal alternative at lower volume. Send a drawing for alloy selection and DFM review Scope and sources. Composition ranges, mechanical values and selection logic were compiled in 2026 from an aluminium casting alloy guide covering A380, A383, A360, A413 and A356 together with finish and draft limits, a cast aluminium datasheet with element-by-element composition tables and a die casting review of the alloys a foundry actually runs. Equivalences between AA, JIS, EN and LM designations are approximate, because the permitted ranges are not identical between standards. Tensile values are as-cast typical figures that move with section thickness and porosity, so treat them as planning bands and confirm against a first-article inspection before releasing a program.

The short answer Aluminium alloys account for over 70 percent of die-cast parts because they combine a strength-to-weight ratio of 200 to 330 MPa at 2.7 g/cm3 with fast 20 to 90 second cycles, thermal conductivity of 92 to 170 W/m.K, as-cast tolerances of plus or minus 0.1 to 0.25 mm and complete recyclability. No competing casting metal delivers all five at the same cost. Six reasons aluminium dominates Aluminium is popular because it is never the best at any single property but is competitive on all of them at once. That balance is what a production decision actually needs. Strength at a third of the weight of steel. Aluminium is about 2.7 grams per cubic centimetre against 7.8 for steel, so a die-cast aluminium bracket carries a comparable structural load at roughly a third of the mass. In vehicles and hand-held products that weight saving is the whole business case. Near-net shape with integrated features. Ribs, bosses, mounting pads, undercuts and internal channels are formed in a single shot that would otherwise need several pressings plus welding and assembly. Net-shape output typically removes 60 to 80 percent of the material waste of machining from billet and cuts total component cost by 20 to 40 percent against fabricated alternatives. Thermal conductivity that does structural work. At 92 to 170 W/m.K, an aluminium housing doubles as a heat sink, which is why motor housings, inverter cases, LED drivers and power modules are cast rather than fabricated. High production rates. Cycle times of 20 to 90 seconds per shot support outputs of tens of thousands to hundreds of thousands of parts per cavity per year once tooling exists. Repeatable as-cast tolerances. Standard as-cast linear tolerance is around plus or minus 0.1 mm for features under 25 mm, widening to plus or minus 0.25 mm over 250 mm, which removes most secondary machining on non-critical features. Recyclability and a mature supply base. Aluminium is recyclable without losing mechanical properties and runner and overflow metal goes straight back into the melt. Modern foundries run substantial recycled content, and alloy supply and machine capacity are available almost anywhere. The numbers behind the claim The following table is the version we use in a quotation review, because these are the figures a purchasing team can test against a competing process. MetricTypical valueWhy it matters commercially Density2.7 g/cm3Structural parts at a third of steel weight Tensile strength as cast200 - 330 MPaCovers brackets, housings and frames Thermal conductivity92 - 170 W/m.KRemoves a separate heat-sink component Injection pressure70 - 150 MPaFills 1 to 4 mm walls reliably Cycle time20 - 90 secondsHigh throughput per cavity As-cast toleranceplus or minus 0.1 to 0.25 mmLess secondary machining Machined toleranceplus or minus 0.02 to 0.05 mmBores and sealing faces still work Die life (H13 tooling)200,000 - 350,000 shotsTooling amortises over a long program Tooling lead time5 - 8 weeksBridge tooling can cut this to 3 - 5 weeks Break-even against machiningabout 3,000 - 5,000 partsWhere the tooling investment pays back Aluminium against zinc, magnesium and steel Comparing the same part across materials is the quickest way to see why aluminium is the default. Zinc wins on precision, die life and cycle time but loses on weight. Magnesium wins on weight but loses on cost and corrosion. Steel wins on strength but cannot be die cast at all, so it competes as a pressing or a weldment. Aluminium is rarely first on any single row; it is the only one that is competitive on all of them. Thermal conductivity is the quiet advantage Strength and weight get the attention, but conduction is the reason aluminium appears in so many electronics and motor applications. A die-cast aluminium housing can act as the heat path itself, so the design deletes a separate heat sink, its fixing hardware and the thermal interface between them. That is a component-count reduction, not just a material substitution, and it frequently decides a program before cost is discussed. At 92 to 170 W/m.K, the part does the thermal work the housing used to need a separate sink for. Inside aluminium: which alloy and when Aluminium is a family, and the grade changes the answer more than most buyers expect. A380 and ADC12 are the general-purpose castability and cost choice for housings, brackets and gearbox covers. A383 is preferred where fill quality on thin walls decides the result. A360 trades a little castability for corrosion resistance and pressure tightness, which matters on anything that must not leak, such as a hydraulic body. A356 T6 is more ductile and heat treatable and is specified for structural and safety-related parts where elongation matters as much as strength. B390 with its high silicon content delivers wear resistance for pump and engine surfaces, at the price of accelerated die wear. When aluminium is the wrong choice Aluminium loses strength above roughly 300 C. Sustained high-temperature service, such as a hot exhaust-side component, usually needs a different material or a different process. Very thin walls with short flow paths belong to zinc. Aluminium reaches about 1.2 mm only over a limited flow length. Claims of 0.8 mm on aluminium generally refer to a test coupon, not a production part. Thick sections are the hardest thing to cast, not the easiest. Above about 8 mm, solidification time rises steeply and the interior shrinks into porosity. Where mass is genuinely needed, core the section out and add ribs. Low volumes cannot carry the tooling. Under roughly 3,000 parts, machining from billet or sand casting is usually cheaper than amortising an aluminium die. Tight bores and sealing faces still need machining. The as-cast tolerance will not hold a bearing fit, so plan the secondary operation into the design and the price. Wrought alloys such as 6061 are not die-casting alloys. They hot-crack and stick, so the alloy must be chosen from the casting family. Cost, break-even and what we need to quote The economics are simple to describe and easy to get wrong. Tooling for aluminium runs from roughly USD 8,000 to USD 80,000 or more depending on size and cavity count, and a typical 0.8 kg casting lands between about USD 3 and USD 5 per part excluding tooling. The break-even against machining usually falls around 3,000 to 5,000 parts. Above that, per-part cost keeps falling as the tool amortises, which is why aluminium die casting is described as the lowest total cost of ownership among precision metal forming routes for annual volumes above roughly 10,000 units. Cycle time is short, so volume rather than speed is what unlocks the price. To quote properly we need the drawing or STEP file, the alloy if you have a preference, the annual volume and expected program life, the load case and the environment, and any surfaces that must remain as-cast. With those we will return DFM feedback on walls, draft and porosity risk alongside the price at two volumes, so the break-even is visible rather than asserted. We cast aluminium and zinc and machine the critical features in house, and the related processes are listed under aluminium die casting, surface finishing and metal stamping for the sheet-metal alternative. Send a part for an aluminium die casting quotation Scope and sources. Property values, cycle times, tooling ranges and break-even points were compiled in 2026 from an overview of aluminium die casting benefits and cost drivers, a design guideline and cost model with NADCA tolerance grades, a die casting process guide covering tooling cost and cycle time and a comparison of aluminium, zinc and magnesium die-cast alloys. Tooling, unit price and die life depend heavily on part geometry, cavity count, alloy and program length, so the figures here are planning bands for budgeting rather than quotations. Confirm them against a DFM review and first-article inspection before committing to a program.

The short answer Four alloy families cover almost all die casting: aluminium, typically ADC12 or A380 and over 70 percent of all die-cast parts; zinc, usually Zamak 3 or Zamak 5 for thin-wall precision parts; magnesium, mainly AZ91D where weight matters; and copper alloys such as C36000 where conduction and wear resistance matter. Selection balances density, strength, casting temperature and cost. The four families at a glance Die casting only works with non-ferrous alloys that melt low enough to spare the hardened steel die. That single constraint excludes steel and cast iron and leaves the four families below, each with a distinct reason to exist. The table is the fastest way to place a part in the right family before arguing about grade. Aluminium is the default, but only for the reasons in the last column. Aluminium alloys: the workhorse family Aluminium is chosen when you need a combination rather than a single property: reasonable strength at low weight, good thermal conductivity, acceptable as-cast tolerance and a mature supply chain. Within the family, the choice is narrower than it first appears. ADC12 and A380. The global workhorse, containing roughly 8 to 9.5 percent silicon and 3 to 4 percent copper. ADC12 is the Japanese and Asian designation for essentially the same alloy family. Tensile strength as-cast is around 250 to 320 MPa with 1 to 3 percent elongation, and fluidity is excellent, which is why it fills thin ribs and complex bosses reliably. A383. A close variant with slightly better fluidity and surface finish, used for thin-walled or decorative parts where fill quality matters more than peak strength. A360. Higher corrosion resistance and better pressure tightness than A380, so it suits parts that must not leak, including hydraulic and fluid-handling bodies. A356 (Al-Si-Mg). More ductile and heat treatable. In the T6 condition it reaches roughly 330 MPa with dramatically better elongation, which is why structural and safety-related parts use it rather than A380. B390. Around 17 percent silicon for wear resistance, used for bearing surfaces, compressor housings and pump bodies. It is abrasive to the die, so die life falls and cost rises. AlloyStrength (MPa)ElongationWhy you would specify it ADC12 / A380200 - 3201 - 3 percentBest balance of castability, cost and strength A383about 2752 - 4 percentThin walls and surface finish A360about 3303 - 5 percentLeak-tight housings and corrosion resistance A356 T6about 330up to 20 percentStructural and safety-critical parts B390about 400under 1 percentWear resistance in pump and engine parts Zinc alloys and thin-wall precision Zinc is the low-temperature family, and that has practical consequences. Zamak 3 melts around 380 to 390 C, so it runs in a hot-chamber machine with cycle times measured in seconds and much lower thermal load on the die. The result is a die life that commonly runs from 500,000 to a million shots against roughly 200,000 to 350,000 for aluminium, and a wall capability down to about 0.4 mm, against roughly 1.2 mm for aluminium over a limited flow length. Zamak 3 is the general-purpose grade with the best combination of castability and cost. Zamak 5 adds roughly 20 percent to tensile strength and is used where the part carries a load. Both cast and machine beautifully, take plating well, and are used for lock hardware, electronic enclosures, camera frames and small precision components. The trade-off is weight: at 6.6 grams per cubic centimetre, zinc is more than twice as dense as aluminium, so it is rarely the right answer for anything large. Low melt temperature is why zinc dies last several times longer than aluminium dies. Magnesium, when weight is the driver Magnesium is the lightest structural die-casting metal at about 1.8 grams per cubic centimetre, roughly a third lighter than aluminium for the same volume, with tensile strength of 225 to 320 MPa and excellent electromagnetic shielding. That combination is why AZ91D and AM60B appear in laptop and camera bodies, drone frames, instrument panels and lightweight vehicle structures. AM60B is the more ductile of the two and is used where impact resistance matters. The costs are real. Magnesium is more expensive than aluminium, it needs a protective atmosphere during melting because the melt oxidises and can ignite, and it has the worst natural corrosion resistance of the three main families, with a salt-spray endurance measured in tens of hours rather than hundreds. Magnesium parts essentially always receive a coating, typically micro-arc oxidation or an electrophoretic finish, and that coating should be costed into the business case rather than treated as optional. Weight is the one property that no amount of alloy development can change much. Copper and brass, for conduction and wear Copper alloys are the small, specialist end of die casting. C36000 free-cutting brass and C83600 and C95400 bronzes offer thermal and electrical conductivity two to three times that of aluminium, plus high hardness and good wear resistance, which makes them the standard choice for electrical connectors, heat-sink inserts, valve bodies and tapware components. The problem is temperature: with melting points from roughly 880 to 1,100 C they are far harder on the die than aluminium, tool life is short and tooling cost is high. Copper die casting is specified for performance, almost never to save money. Alloy limits and what rules a material out Knowing the limits saves more money than knowing the advantages. These are the constraints that most often force a change of family after a part has already been designed. Ferrous metals cannot be die cast. Steel and cast iron melt far above the temperature the die can survive, and the same applies to titanium. Those parts belong in investment or sand casting, or in machining. Wrought alloys such as 6061 are unsuitable. The alloying is optimised for extrusion and machining, not for high-velocity fill, and it tends to hot-crack and stick to the die. Wall thickness has a window, not just a minimum. Aluminium works best between about 1.5 and 4 mm and becomes difficult above roughly 8 mm, because solidification time scales with the square of section thickness and thick sections shrink into internal porosity. Porosity is inherent to high-pressure fill. Trapped gas and shrinkage voids limit weldability and rule out conventional heat treatment of standard castings. Vacuum-assisted machines reduce it but add cost. Bearing bores and sealing faces should be machined. As-cast tolerance is around plus or minus 0.1 to 0.25 mm; secondary machining takes critical features to plus or minus 0.02 to 0.05 mm. Volume has to justify tooling. Below roughly 3,000 to 5,000 parts, the tooling amortisation usually makes machining or sand casting cheaper overall. Material selection at SOMI We cast aluminium and zinc alloys and machine the critical features afterwards, so the recommendation we give is based on the part rather than on what a single machine happens to run. Send the drawing or the STEP file with the load case, the environment and the annual volume, and we will come back with the alloy, the wall and tolerance expectations, the tooling position and the price at two volumes so the break-even is visible. See aluminium die casting, surface finishing for the coating options and plastic injection moulding if the part does not need metal. Send a part for alloy selection and DFM review Scope and sources. Alloy properties, densities and temperature ranges were compiled in 2026 from a comparison table of aluminium A380, ADC12, magnesium AZ91D, Zamak 3 and Zamak 5, a die casting material overview covering aluminium, zinc, magnesium and copper alloys and an aluminium die casting alloy guide. Die life, minimum wall and tolerance figures follow published shop capability limits and NADCA product standards rather than a single test report. Commercial values vary with alloy lot, part geometry, machine tonnage and tool maintenance, so treat every range here as a planning band and confirm against a quotation and first-article inspection.