Die Casting

The short answer Zinc wins on strength per unit volume and on thin walls; aluminium wins on strength per kilogram. Zamak 3 reaches 215 to 283 MPa tensile with about 10 percent elongation, against about 320 MPa with 1.5 to 3.5 percent for A380. Zinc is 2.4 times denser, so aluminium wins any weight-driven programme. Strength: the same headline number, two different meanings Zinc and aluminium are quoted with tensile strengths in the same range, and that is where the confusion starts. The headline figure says nothing about how much of that strength is available per kilogram, and nothing about how the material behaves when it is overloaded. Both matter more than the tensile number itself, so the comparison has to be read column by column rather than row by row. The tensile row looks like a tie. The yield row, the elongation row and the density row do not. Property, as castA380 aluminiumZamak 3 zincZamak 5 zinc Tensile strengthAbout 320 to 325 MPa215 to 283 MPa270 to 331 MPa Yield strengthAbout 160 MPa140 to 221 MPaAbout 210 MPa Elongation at break1.5 to 3.5 percentAbout 10 percentAbout 7 percent Brinell hardness75 to 80 HB82 HB89 to 91 HB Density2.71 to 2.76 g/cm36.60 g/cm36.60 g/cm3 Melting point540 to 660 °C381 to 387 °C380 to 386 °C Minimum wall thickness2.3 to 2.5 mm0.5 to 1.0 mm0.5 to 1.0 mm Thermal conductivity96 W/m-K113 W/m-K109 W/m-K Die life, typical shots100,000 to 300,000500,000 to 1,000,000500,000 to 1,000,000 Raw material cost index1.00 baseline0.70 to 0.850.75 to 0.90 Casting processCold chamberHot chamberHot chamber Two readings matter. First, Zamak 3 has a lower tensile figure than A380 in most tables and a higher yield figure, which means it reaches its working stress with less permanent deformation. Second, the elongation column is the one that predicts failure in service: zinc stretches about three times as far before it cracks, so a zinc part absorbs impact and tolerates assembly bending that would break a comparable aluminium part. The density penalty is the real dividing line Density is the single most decisive figure in the comparison. Zinc is 6.60 g/cm3 against 2.71 to 2.76 g/cm3 for A380, so it is 2.4 times heavier for the same geometry. A zinc part weighing 100 grams weighs about 41 grams in aluminium. Normalising strength by density makes the trade explicit: A380 lands near 116 to 120 MPa per unit of specific gravity, while Zamak 3 lands near 43 and Zamak 5 near 50. Per kilogram, aluminium is about 2.4 to 2.8 times stronger. Per cubic centimetre, zinc is the more efficient material. That is why the two alloys end up in different product families rather than competing for the same one. Wherever weight drives a functional or economic outcome — vehicle fuel economy, shipping cost, a handheld product, a structural housing — aluminium wins and the density row settles the argument before any property table is consulted. Wherever the part is small and heavy use is not a concern, the density penalty is irrelevant and the zinc advantages become decisive. Elongation and impact: where zinc wins outright Zinc has roughly 10 percent elongation as cast and aluminium about 3.5 percent, and the gap is not a rounding difference. A material that stretches 10 percent before it breaks absorbs energy that a material stretching 3.5 percent does not, so zinc parts survive drop tests, crimping, staking, press fits and assembly torques that crack the same geometry in aluminium. Zinc also delivers higher hardness, 82 to 91 HB against 75 to 80 HB, which translates into better wear behaviour in mechanisms that rub. Published elongation for the same alloy varies with section thickness and casting quality, so read the chart as a ranking rather than a specification. The exception is temperature. Zinc creeps under sustained load above about 100 °C, and intergranular corrosion is a real risk if the alloy is made from contaminated scrap rather than from specified high-grade ingot. Where a part runs hot or has to be welded, aluminium takes over regardless of the elongation advantage. Cost: what actually drives the per-part figure The zinc alloy itself is cheaper per kilogram than A380 — the material index sits at roughly 0.70 to 0.85 against an aluminium baseline of 1.00 — but the density penalty reverses that on a per-part basis for anything large, because 2.4 times the density means about 2.4 times the metal in the same geometry. Per-part cost therefore comes down to four things that have nothing to do with the price of the ingot. Cost driverZinc (hot chamber)Aluminium (cold chamber)Effect on unit cost Die life500,000 to 1,000,000 shots100,000 to 300,000 shotsTooling amortised over 3 to 5 times as many parts Cycle time300 to 500 shots per hour on small parts5 to 15 seconds longer per shotLower machine cost per part for zinc Melting temperature381 to 387 °C540 to 660 °CLess energy per kilogram melted Material mass per part2.4 times the aluminium massBaselineReverses the price advantage on large parts Tooling investmentSimple dies from about USD 15,000Large structural dies above USD 300,000Lower entry cost and lower change cost for zinc Put together, zinc is usually the cheaper route for small, intricate parts, where thin walls, long die life and a fast hot-chamber cycle outweigh the metal mass. Aluminium is usually the cheaper route for large parts, where its lower density means less metal, less weight and a smaller machine. The crossover is not a single quantity: it depends on part size, wall thickness, cavity count, annual volume and how much secondary machining the casting needs. Choosing between them Choose zinc when the part is small, weight is not critical, walls thinner than 1 to 1.5 mm are needed, the as-cast tolerance has to hold within about plus or minus 0.05 to 0.1 mm, the surface has to plate directly, or ductility is needed for staking, crimping or assembly. Choose aluminium when weight drives the design, the part is large, service temperature exceeds about 100 to 120 °C, the part has to be anodised, or the programme needs pressure tightness and the option of impregnation. Choose zinc for the tool, aluminium for the part, when volumes are high. A zinc hot-chamber die lasts three to five times as long, so a programme that can use zinc tooling and aluminium parts is unusual but not impossible, and the two materials are not interchangeable within one die. Check the finishing route before the alloy is fixed. Zinc plates directly and takes a mirror polish; aluminium needs pretreatment before plating but can be anodised in colour. The finish often decides the alloy rather than the other way round. Limits and open questions Published property tables disagree. Tensile strength for Zamak 3 is quoted from 215 to 283 MPa and elongation for the same alloy from 7 to 13 percent depending on source, section thickness and casting quality. Treat any single number as an indicative value and test a coupon in the real section thickness. Die life depends on the die, not only the alloy. The 500,000 to 1,000,000 shot figure for zinc assumes good thermal management and correct maintenance; some foundries publish a more conservative 200,000 to 500,000, especially on dies with long cores and slides. Zinc creeps when it is hot. Sustained loads above roughly 100 °C cause dimensional change, so zinc is the wrong choice for engine-adjacent, lighting or heat-soak components. Corrosion protection is not optional outdoors. Zinc develops a stable oxide layer in clean air, but outdoor and marine service still needs plating, powder coating or a conversion coating, and plated parts need the plating specified rather than assumed. Aluminium is not pressure tight without help. A380 can be impregnated to seal porosity, which is an extra operation; casting quality and process control decide whether it holds. No certification is implied here. Which quality system applies to a given programme is confirmed per programme and per factory in writing before production. What to send for a material recommendation Send the 3D model, the toleranced 2D drawing, the annual volume, the load path, the service temperature and the finish required. Those six items settle the alloy before price is quoted: a weight-critical or hot-running part points to aluminium, a small thin-wall or impact-loaded part points to zinc, and a part that needs a mirror-plated surface points to zinc for reasons that have nothing to do with strength. See aluminium die casting for large structural and thermal parts, surface finishing for the plating and coating routes, and send a drawing for a free design review that compares both alloys on your part. Send a drawing and get a zinc or aluminium recommendation Scope and sources. Property ranges and cost drivers were compiled in 2026 from an aluminium and zinc die casting comparison (A380 at 325 MPa and 160 MPa yield, Zamak 3 at 215 to 250 MPa, Zamak 5 at 270 to 310 MPa, density 2.71 against 6.60 g/cm3, melting 540 to 660 °C against 381 to 387 °C, Brinell 80 against 82 and 91 HB, minimum wall 2.3 to 2.5 mm against 0.8 to 1.0 mm, die life 100,000 to 300,000 shots against 500,000 to 1,000,000, raw material index 0.70 to 0.90) and from a zinc die casting alloy reference (Zamak 3 at 283 MPa and 10 percent elongation, Zamak 5 at 328 MPa, A380 at 317 MPa, density 6.60 against 2.74 g/cm3, calculated specific strength of 43 against 116 MPa per unit density, and the intergranular corrosion risk from contaminated scrap). Alloy and application data were checked against a die casting materials guide and a zinc alloy property table. Cycle rate, machine economics and tooling price bands come from a die casting process and lead-time review (small zinc parts at 300 to 500 shots per hour in a hot chamber, cold chamber adding 5 to 15 seconds per shot, a simple zinc die from about USD 15,000, a large structural aluminium die above USD 300,000). These are typical published as-cast values; section thickness, casting parameters, alloy lot and finishing route all move them, and none of the figures is a specification for a particular part. Nothing on this page states or implies a certification held by any supplier.

The short answer Zinc die casting suits small to medium parts that need thin walls, fine detail, tight as-cast tolerance and a platable finish: locks and door hardware, plumbing fittings, electrical connectors, power-tool and appliance parts, and decorative components. It is the wrong choice for large, weight-critical or high-temperature parts. Six product families, and why zinc fits each Zinc is not selected because it is the strongest die casting alloy; it is selected because it fills a thin, detailed cavity and comes out of the die close to finished size with a surface that plates directly. That combination of properties defines a much narrower product family than the phrase metal parts suggests, and it is worth knowing which families actually use it. Detail, thin walls and plating quality decide these families, not tensile strength. Product familyTypical partsWhy zinc fitsUsual alloy Locks and securityLock bodies, cylinders, key blanks, padlock shells, handle basesFine detail and keyways cast in, durable under platingZamak 3, Zamak 5 for load-bearing parts Door and furniture hardwareHandles, hinges, cabinet pulls, door stops, window hardwareThin decorative sections with a platable surfaceZamak 3 Plumbing and bathroomFaucet handles, shower brackets, angle valve housings, fixture basesSmooth cast surfaces and good plating adhesionZamak 3 or 5 Electrical and electronicConnector housings, relay and contactor housings, switchgear partsThin walls, tight tolerances and screening better than plasticZamak 3 or 5 Automotive interior and small mechanismsDoor lock parts, seat latches, sensor housings, trim hardwareAccuracy and ductility in small loaded partsZamak 5, ZA-8 Tools, appliances and consumer goodsSwitch housings, speed-control knobs, trigger parts, luggage locks, zipper pullsLow unit cost at volume with a good finishZamak 3 or 5 Decorative and fashion hardwareBuckles, medallions, badges, eyeglass hinges, stationery fittingsReproduces fine texture and takes a mirror plateZamak 3 The families share a common shape profile: small, often intricate, frequently visible to a user, and produced in thousands rather than millions. If the part is large, hidden inside a machine and judged only on function, another material is almost always cheaper. The criteria a part has to pass Four requirements do most of the sorting, and they can be checked against a drawing in a few minutes. The first is size and weight: zinc parts are economical from a few grams up to about 1.5 kg, and the process can technically reach higher, but the density penalty makes large zinc parts expensive and heavy. The second is wall thickness, which is where zinc has a genuine advantage over aluminium and where most thin-wall hardware designs are won or lost. Walls below about 1 mm are routine in zinc and require a different process and alloy choice in aluminium. The third criterion is as-cast accuracy. Zinc hot-chamber casting holds roughly plus or minus 0.05 to 0.1 mm as cast, against about plus or minus 0.1 to 0.2 mm for aluminium, so a zinc part often needs no machining at all on its functional features — a direct saving on any part with several toleranced features. The fourth is volume and finish: zinc tooling lasts 500,000 to 1,000,000 shots on a good die, which is what makes it economical on high-volume parts where the per-part tooling amortisation is worth more than the metal price. A part qualifies when the first three answers are yes and the fourth is a preference rather than a constraint. Where zinc is the wrong choice Weight-critical parts. Zinc is 6.60 g/cm3 against 2.71 to 2.76 g/cm3 for aluminium. Any handheld, vehicle or portable product where every gram is budgeted should start with aluminium or magnesium. Large structural parts. Housings, frames, battery enclosures and motor covers are aluminium territory. Zinc gives no structural advantage that compensates for 2.4 times the mass. Parts that run hot. Zinc creeps under sustained load above about 100 °C, so engine-adjacent, lighting and heat-soak components are excluded regardless of geometry. Parts that have to be anodised. Zinc cannot be anodised. It plates and coats well, but the hard coloured oxide finish that aluminium takes in a single operation is not available on zinc. Parts needing welded assemblies. Zinc is not a welding-friendly die casting alloy, so a fabrication that has to be joined by welding belongs to steel, aluminium or a different process. Pressure-tight parts without a sealing plan. Castings can be porous. Where fluid has to be contained, the design needs a sealing or impregnation step, and that has to be planned before the die is cut rather than discovered at leak test. Finish is usually the reason the part is zinc at all Many zinc parts are visible parts, and the reason they are zinc is that the hot-chamber surface replicates a polished die closely enough to plate directly. A standard bright chromium sequence runs an alkaline clean, a 3 to 8 micrometre copper strike that seals micropores, a 15 to 30 micrometre bright acid copper layer that levels the surface, then 8 to 15 micrometres of nickel before the decorative chrome. That stack is what produces the mirror finish on door hardware and bathroom fittings, and it is far harder to achieve on an aluminium casting because aluminium needs pretreatment and still plates less uniformly. Where plating is not wanted, zinc also takes powder coating, liquid paint and chemical conversion coatings, and a well-run casting often meets a cosmetic requirement without any finishing at all. Both routes raise a caution worth writing into the specification: coated and plated zinc parts intended for outdoor or wet service need the coating thickness and adhesion test specified, because zinc corrosion protection depends on the coating being intact rather than on the base metal. What to send for a quoted part Send the 3D model, the toleranced drawing, the annual volume, the surface finish or plating required and the environment the part will see. Those five items decide whether the geometry and the volume suit zinc before price is discussed: a small, detailed, plated part with walls under 1 mm points to zinc in a hot chamber machine, and the same shape above about 1.5 kg or running hot points to aluminium instead. See surface finishing for the plating and coating routes that finish most zinc parts, aluminium die casting for the weight-critical alternative, and send a drawing for a free design review. Send a part drawing and get a zinc die casting review Scope and sources. Application families and part lists were compiled in 2026 from a zinc die casting capability summary (part weight range 0.001 to 10 kg, minimum wall down to 0.5 mm, dimensional accuracy to IT5 to IT7, tool life 200,000 to 500,000 shots, application lists covering automotive, electrical, locks and hardware, plumbing, telecom, medical, consumer goods and power tools) and from a Zamak die casting application guide (Zamak 3 for general hardware and housings, Zamak 5 for load-bearing hardware and locks, Zamak 7 for thin-wall detail, ZA-8 for wear resistance; automotive door hardware, electrical connectors, consumer electronics casings, lock mechanisms and furniture hardware). Wall thickness, tolerance and material cost context come from an aluminium and zinc die casting comparison (zinc minimum wall 0.5 to 1.0 mm, aluminium 2.3 to 2.5 mm, as-cast tolerance plus or minus 0.05 to 0.1 mm against 0.1 to 0.2 mm, die life 500,000 to 1,000,000 shots) and from a zinc die casting service overview (cycle times 10 to 20 seconds, shrinkage 0.5 to 1 percent, as-cast finish Ra 1.6 to 3.2 micrometres, thin walls to 0.5 mm). The plating sequence and its layer thicknesses come from a zinc die casting alloy reference (3 to 8 micrometre copper strike, 15 to 30 micrometre acid copper, 8 to 15 micrometre nickel). These are typical published figures for general-purpose hot-chamber machines and ordinary part designs; geometry, alloy, cavity count and finishing route all move them. Nothing on this page states or implies a certification held by any supplier.

The short answer Plan on 8 to 12 weeks for new aluminium die casting tooling: about 2 to 3 weeks of die design, 4 to 6 weeks of steel machining and 1 to 2 weeks each of benching and tryout. First production then runs 3 to 4 weeks, and repeat orders 2 to 3 weeks. The project in four milestones, not one number A single lead-time figure is the least useful number a buyer can be given, because the clock starts and stops in different places for different suppliers. One quotation may promise T1 samples at week ten and another may promise parts ready to ship at week ten, and both can be described as a ten-week lead time. The only reliable answer is a milestone plan, and it has four gates. Ask which gate each quoted date refers to. A date without a gate is a guess. The clock should not start while essential information is missing. A usable request for quotation includes a 3D model, a toleranced 2D drawing, the alloy, the order quantity and annual forecast, the finish required and the inspection requirements. Quotation and design-for-manufacture feedback normally come back in 1 to 2 working days once that package is complete, and the tooling window opens only when the drawing revision is frozen. That single discipline is the biggest available saving on any die casting schedule, because a drawing change during steel cutting adds one to four weeks. Inside the tooling window, phase by phase Most of the tooling window is consumed by one phase, and it is not the phase buyers expect. Design is comparatively quick; cutting the cavity, cores and slides out of H13 hot-work tool steel is not, and it is where complexity shows up as weeks. Machining is roughly half the tooling window. Adding slides, lifters or unscrewing cores adds 30 to 50 percent on top. Tooling phaseTypical durationWhat has to be finished to move onWhat commonly extends it Design and engineering2 to 3 weeksDie layout, cooling, gating and ejection approvedUndercuts found late; drawing revisions Steel machining4 to 6 weeksCavity, cores and slides cut in H13 steelExtra slides, side cores, specialty steel lead time Benching and polishing1 to 2 weeksMoving parts assembled, surfaces finishedDeep texture or mirror finish on large areas Tryout and qualification1 to 2 weeksSamples measured, first article signed offFailed trial, dimensional correction, resampling Two details are worth planning for. First, it is rare for a new die to produce conforming parts on the first day of trials; most programmes budget two to four rounds of trials over two to six weeks to tune injection speed, fill pressure, die temperature and cooling time. Second, where a programme needs documented part approval, the documentation phase adds a further two to four weeks after the parts pass dimensional inspection, and that work runs on the critical path rather than in parallel with it. Total lead time by project type Adding the phases together produces four recognisable project bands. They are planning ranges rather than promises, and the difference between the first and the last is almost entirely complexity — side actions, vacuum systems, large dies and documentation. Prototype tooling is a different process, not a faster version of production tooling: lower volume, lower accuracy. Project typeTooling order to first approved shipmentWhat drives the figure Prototype, soft tooling (aluminium or kirksite)2 to 4 weeksLimited volume, lower accuracy, no production die Simple part, no side actions, non-automotive8 to 14 weeksSingle cavity, moderate geometry, standard inspection Medium-complexity automotive part14 to 22 weeksSlides, tighter tolerances, trial rounds, approval paperwork Large structural part with vacuum die casting20 to 30 weeksLarge multi-core die, process capability studies, full documentation The prototype row deserves a caution of its own. Soft tooling delivers samples in weeks rather than months, and it is the right route for design validation, but it is not a production die: cavity life is short, dimensional consistency is looser and the process window is narrower. Parts approved on soft tooling still have to be re-qualified on the production die. What shortens the schedule, and what extends it A frozen drawing is the largest single saving. Releasing a numbered, fully detailed revision before steel is cut removes the one to four weeks that drawing changes otherwise add. A completed inlet package starts the clock earlier. Model, toleranced drawing, alloy, volume, annual forecast, finish and inspection requirements, all in the first message, are worth days at the front of the project. Simpler geometry is faster geometry. A two-plate die without slides is the fastest route; dies with slides, lifters, unscrewing mechanisms or vacuum systems take 30 to 50 percent longer to build. Standard steel is quicker than special steel. H13 is normally in stock; a specialty grade has to be sourced, and that sourcing time sits directly on the critical path. Define what T1 approval means before the trial. Vague acceptance criteria produce repeated discussion after sampling, which is the most common cause of a project that runs long without any technical problem. Rush tooling is possible and is priced accordingly. Compressing tooling to four to six weeks is achievable with dedicated machining capacity, and it usually carries a premium of roughly 25 to 40 percent, with a higher trial count as the trade. Production lead time after the die is approved Once the die is qualified, the schedule changes character: it is now driven by material, machine capacity and secondary operations rather than by tool building. A first production run is typically quoted at 3 to 4 weeks and a repeat order at 2 to 3 weeks on an existing, maintained die. That window covers material procurement for standard alloys, die setup and preheating, the casting run itself, dimensional and visual inspection, any secondary machining, finishing or leak testing, and packing. Casting time is rarely the constraint. On a one-minute cycle, a 10,000-part run occupies roughly one to two weeks of machine time, so above about 50,000 pieces the run becomes the dominant part of the schedule and cavity count is the lever that shortens it. Secondary operations are the other variable: a part that needs machining on a fixture, a coating that requires approval, a leak test or a full dimensional report each creates its own path, and the schedule has to follow the finished part rather than the casting. Limits: what a quoted lead time does and does not include Ask what starts the clock. Some suppliers start at purchase order, others at design approval. The difference is two to three weeks on the same project. Ask whether sampling is inside the tooling figure. Trial shots, correction and resampling often sit outside a quoted tooling time, and they are the phases most likely to overrun. Transport is usually excluded. Air freight runs about 3 to 7 days and sea freight 25 to 40 days, and only one of those is compatible with a tight launch date. A dormant die is not a ready die. A repeat order on a die that has been idle may need inspection, maintenance or repair before it can run, which can add days that a repeat-order quotation does not mention. Rush schedules trade risk for time. Compressed tooling raises the number of trial rounds and leaves less room for correction, so a fast die is not automatically a low-risk die. No certification is implied here. Which quality system applies to a given programme, and which documents are supplied with the parts, is confirmed per programme and per factory in writing before production. What to send for a firm schedule Send the 3D model, the toleranced 2D drawing with callouts referenced to datums, the alloy if it is fixed, the order quantity and annual forecast, the finish and inspection requirements, and the date the parts have to be in hand. Those seven items turn a vague lead-time estimate into a milestone plan with named gates. See aluminium die casting for the process and alloy routes, CNC machining for the secondary operations that often sit on the critical path, and send a drawing for a project-specific schedule. Send a drawing and get a milestone-based lead time Scope and sources. Phase durations and total lead-time bands were compiled in 2026 from a die casting lead-time guide (quotation and DFM feedback in 1 to 2 working days, mould manufacturing about 25 to 35 days for standard projects, T1 sampling and correction as a separate gate) and from a die casting process review (a medium-complexity single-cavity aluminium tool 6 to 10 weeks and 10 to 16 weeks with multiple side actions, 2 to 4 trial rounds over 2 to 6 weeks, documentation adding 2 to 4 weeks, total 8 to 14 weeks for a simple non-automotive part, 14 to 22 weeks for a medium-complexity automotive part, 20 to 30 weeks for a large structural part with a full approval package, and 2 to 4 weeks for prototype soft tooling). Production-run and repeat-order windows, the 8 to 12 week tooling band, the 4 to 6 week rush band and the documentation allowance come from a die casting supplier selection guide and a custom aluminium die casting lead-time summary (production 2 to 4 weeks for modest orders, 6 to 8 weeks for heavily machined or large orders, design freeze to production authorisation 14 to 20 weeks). Tooling cost context and the observation that 4 to 6 week quotations from some regions exclude design review come from the same process review. These are planning ranges, not commitments: part size, cavity count, side actions, tool steel availability, drawing maturity, inspection scope and shipping method all move them, and every figure is confirmed against a specific drawing before it is quoted. Nothing on this page states or implies a certification held by any supplier.

The short answer Aluminium die casting suits vehicles and aircraft because one process delivers thin-wall complexity, low mass and a heat path at automotive volume. Density is 2.7 against 7.8 g/cm3 for steel, walls go to 1.5 mm, thermal conductivity is 90 to 120 W per metre-kelvin, and a shot takes 30 to 90 seconds. What a vehicle asks for, and which property answers it A car and an aircraft are not asking for a material. They are asking for a set of outcomes, and high-pressure die casting answers five of them in a single operation. Read the chart below as a requirements list rather than as a sales sheet: each row pairs an outcome the programme is measured on with the material or process property that delivers it. Five requirements, one process. Where a row has no counterpart in your part, a different casting route is probably the right one. Vehicle requirementProperty that answers itTypical figure MassDensity about one third of steel2.7 against 7.8 g/cm3 Thin-wall complexity1.5 mm walls, cast-in bosses and ribsOver thirty welded parts become one Heat pathThermal conductivity, five times steel90 to 120 W per metre-kelvin Rate and repeatabilityA single master cavity producing identical shots30 to 90 seconds per shot Service lifeA self-healing oxide layer and a metal creditAround 95 percent recyclable Two of those rows are economic and three are engineering. The engineering rows are what make die casting difficult to replace in a modern vehicle; the economic row is why it displaces sand casting once the annual volume is there. Mass: the requirement that starts most programmes Aluminium die casting alloy has a density near 2.7 grams per cubic centimetre, against about 7.8 for steel and roughly 7.2 for cast iron. That single line drives everything downstream of it. Published comparisons put the mass saving from substituting die-cast aluminium for cast iron at 40 to 50 percent on a powertrain part: a cast-iron engine block at 120 to 150 pounds against 70 to 90 pounds for the aluminium equivalent, a transmission housing at 20 to 25 kilograms against 40 kilograms and up in steel, a control arm at 2 to 3 kilograms against 4 to 5, and a brake caliper at 1.5 to 2 kilograms against 3 to 4 in cast iron. A normalised comparison, not a strength chart. Every row is the same measurement, so the bars are directly comparable. Those savings are not cosmetic. Published rule-of-thumb figures attribute a 6 to 8 percent fuel-economy gain to every 10 percent of vehicle mass removed, and in a battery-electric vehicle the same mass appears directly as range, with one estimate putting 10 to 15 percent more range on every 100 kilograms taken out. Aluminium already accounts for more than 80 percent of the non-ferrous metal content of a modern car, and automotive recycling rates above 75 percent are why the material retains its value at end of life rather than becoming a disposal cost. Thin walls, cast-in bosses and one part replacing thirty High-pressure die casting fills a hardened steel cavity at gate velocities of 30 to 100 metres per second under 10 to 175 megapascals of pressure. That is what allows a local wall of 1.2 to 1.5 millimetres where a boss or a rib carries the load, and a general wall of 1.5 to 3.5 millimetres elsewhere. Thin walls are not a cosmetic achievement: they are what lets a designer place ribs, bosses and mounting features in the same shot instead of welding or bolting them on afterwards. A published example is a die-cast subframe that replaces more than thirty welded steel parts, removing 15 to 20 kilograms of mass and most of the assembly steps with it. Consolidation is where the second-order savings sit. Every joint that disappears is a fixture, a weld, an inspection and a leak path that no longer exists, and a casting that arrives as one body is dimensionally consistent from the first shot to the hundred-thousandth, because the die is the master negative. That repeatability is what makes die castings attractive to a line that is assembling thousands of vehicles a year. As-cast tolerance is the honest boundary of the claim. High-pressure die casting is normally quoted at ISO 8062 grade CT4 to CT6, which lands near plus or minus 0.1 to 0.25 millimetres on a linear feature with roughly 0.3 millimetres of flatness per 100 millimetres. Machining is what buys better: leave 1.0 to 1.5 millimetres of stock on the faces that carry a dimension and expect those faces to hold plus or minus 0.05 millimetres after a light pass. The window is narrow. Under the lower band the cavity will not fill; over the upper band the last metal to freeze pulls a void. Heat, corrosion and the end of life The third engineering reason is thermal. Aluminium die casting alloys conduct heat at roughly 90 to 120 watts per metre-kelvin, several times the rate of steel, which is why the same process produces engine and transmission housings, power-electronics enclosures, heat sinks and battery trays where the part is also the heat sink. In an electric vehicle the battery tray is a structural member, a shield and a cooling surface at the same time, and a casting that performs all three replaces three parts and two assembly steps. Corrosion resistance comes from the oxide layer that re-forms on aluminium within minutes of a fresh cut, which is why many under-hood castings need no coating at all. Where appearance or chemical exposure demands more, the same castings take anodising, chromate conversion, powder coating or paint, and the surface treatments are chosen per programme rather than built into the alloy. At end of life the material is a credit: published figures put aluminium die castings at around 95 percent recyclable, and remelting aluminium needs roughly 750 degrees Celsius against 1500 degrees for steel, which is the basis of the large energy saving usually quoted for recycled aluminium. Where aluminium die casting meets its limits The alloy is not heat treatable. A380 and ADC12, the two workhorses, are not suitable for T6 solution treatment. A part that needs T6 strength and ductility belongs in gravity or low-pressure casting with A356, not in a die. Porosity is real and measurable. A gate velocity near 42 metres per second inevitably traps air, and published measurements put gas porosity in conventional high-pressure die casting at 1.2 to 2.5 percent by volume. Pressure-tight or fatigue-critical parts need vacuum assist, squeeze casting or a different process. Aerospace is a qualified niche, not a default. Aircraft structures are dominated by wrought and gravity-cast material. Die casting appears in housings, brackets and instrument enclosures, and each part is qualified against the programme's own specification rather than a general one. Size has a ceiling. Most aluminium die casting machines work within roughly 600 millimetres and about 20 kilograms, which rules out large structural sections regardless of volume. Every engineering change is a die revision. A geometry that is still moving is expensive to iterate here, because the correction is cut into hardened steel. Quality paperwork is a programme requirement. Where a programme needs a specific file, certificate or traceability record, it is confirmed per project and per factory in writing before production starts, not assumed from the process name. What to send for an automotive or aerospace quote Send the 3D file as a STEP model, a toleranced drawing, the annual volume and the projected lifetime, the two or three features that actually matter, and the environment the part will see. Those five items decide the process before price is discussed: a thin-wall enclosure with cast-in bosses and a 50,000-a-year forecast points at die casting, the same geometry at 800 pieces a year points at CNC machining, a pressure-tight body points at vacuum-assisted casting, and a part that needs T6 points at gravity casting. See aluminium die casting for the process itself, CNC machining for the faces that carry a dimension, and surface finishing for what happens after the shot. Send a drawing and get a process recommendation Scope and sources. Process mechanics, machine envelope, gate velocity, pressure range and the T6 limitation come from a 2026 high-pressure die casting process specification (400 to 4,000 tonnes clamping force, 10 to 175 MPa injection, melt at 650 to 710 degrees Celsius, gate velocity 30 to 100 metres per second, cycle 15 to 90 seconds, minimum wall 1.5 mm, Ra 1.6 to 3.2 micrometres, ISO 8062 CT4 to CT6, A380 and ADC12 not heat treatable to T6, tooling USD 15,000 to 80,000, economic above 5,000 pieces a year) and from an OEM process comparison (local wall 1.2 mm, structural average 2.0 mm, tolerance near plus or minus 0.08 mm per 100 mm, as-cast skin 3.2 to 6.3 micrometres Ra, 42 metres per second gate velocity giving 1.2 to 2.5 percent gas porosity, 1.0 to 1.5 mm machining stock, 0.5 to 1.0 mm dense skin depth). Mass, thermal and recycling figures come from a fuel-efficiency analysis of high-pressure die casting (thin walls 1.2 to 3.5 mm, 10 percent of mass removed worth 6 to 8 percent fuel economy, a subframe replacing over thirty welded parts and removing 15 to 20 kg, around 95 percent recyclable, remelt at 750 degrees Celsius against 1500 for steel) and from a guide to aluminium die casting applications (engine block 120 to 150 pounds against 70 to 90, transmission housing 20 to 25 kg against 40 kg and up, control arm 2 to 3 kg against 4 to 5, battery housing 100 to 150 kg, 100 kg of mass worth 10 to 15 percent of range, as-cast tensile strength 250 to 400 MPa). Alloy-level properties, the A356 caveat and tolerance figures come from a die casting design and cost guideline and from an automotive die casting design guide (A380 tensile 310 to 345 MPa, ADC12 300 to 330 MPa, A356 in gravity and low-pressure casting only, linear tolerance near plus or minus 0.25 mm, wall thickness plus or minus 0.10 mm, cycle 30 to 120 seconds). Density and recycling context also draw on a non-ferrous automotive materials review (aluminium above 80 percent of non-ferrous content, automotive recycling above 75 percent). Figures are published planning ranges for 2026, not quotations for a specific part, and the correct process for any given component is confirmed against its own drawing.

The short answer At high volume die casting wins on unit price, but only above a crossover that lands somewhere between 500 and 3,500 pieces depending on the die cost. Below it CNC machining is cheaper because there is no tooling to repay. The honest answer is often hybrid: cast the body, machine only the features that carry a dimension. The decision is one division, so run it on your own numbers The whole comparison collapses into a single line: crossover quantity equals tooling cost divided by the difference between the machined and the cast unit price. Published comparisons put that crossover anywhere from about 500 pieces for a small aluminium housing to 3,571 pieces in a worked example with a USD 30,000 die, and to 1,176 pieces where a USD 50,000 die offsets a USD 45 machined part against a USD 2.50 casting. The spread is not sloppiness, it is the arithmetic: change the die price or the machining rate and the answer moves. Each marker is a single published example. Plot your own two unit prices and your own die quote on the same axis before committing. What is stable is the shape of the two cost curves rather than their crossing point. Machining spreads almost nothing up front and holds a roughly flat unit cost at any quantity. Casting spends a five-figure sum before the first part exists and then produces parts at a fraction of the machined price, so the per-part figure falls steeply as volume climbs. A published comparison puts a 100-piece order at about USD 220 per part once tooling is amortised, 10,000 pieces at about USD 4 per part against USD 15 machined, and a 100,000-piece programme at USD 1.28 million total against USD 2.17 million for the machining route. Seven lines where the two processes do not overlap Volume decides the price, but capability decides whether the part can be made that way at all. The seven rows below are the ones that most often override a favourable volume calculation, and they are worth checking before the tooling question is asked. As-cast tolerance is the widest gap on the list, and it is the one that most often forces a hybrid route. CriterionDie castingCNC machining As-cast toleranceplus or minus 0.1 to 0.3 mmplus or minus 0.005 to 0.05 mm Surface finish, Ra1.6 to 3.2 micrometres0.8 to 1.6 micrometres Minimum wall1.2 to 2.0 mm0.8 mm on a damped fixture Material strengthADC12, about 240 MPa tensile6061-T6, about 310 MPa tensile Material turned into chipsnear zero, cast to shape50 to 80 percent of the billet Lead time to first part6 to 10 weeks for a production die5 to 10 days Minimum economic run500 to 1,000 piecesone piece The first two rows are why so many "die casting" parts still visit a machining centre. A cast body can hold plus or minus 0.2 millimetres on a general feature, but a bearing bore, a sealing groove or a mating face at plus or minus 0.02 millimetres cannot be cast. The practical answer is a hybrid: a near-net casting plus a light machining pass on the ten or twenty percent of the part that has to be accurate. That route keeps most of the casting economy and buys the tolerance where it is needed. The casting quote is not the delivered cost This is the mistake that ruins the comparison. A die-cast quotation usually covers the shot, the runners and the flash trimmed off, and nothing else. Machining quotations usually bundle every feature into one number, which makes the casting look far cheaper than it is. Published secondary-operation ranges add USD 0.50 to 2 for trimming, USD 0.50 to 3 for deburring, USD 5 to 30 for machining the critical features and USD 2 to 10 for finishing, which is how an as-cast figure of USD 8 reaches USD 15 to 30 delivered. Ask for a fully-loaded delivered price from both routes. The cheaper quotation is the one that ships good parts, not the one that counts them. Three costs sit outside the unit price and often decide real programmes. Lead time is one: a production die takes six to ten weeks while a machined first article takes days, so a launch deadline can force machining even where the volume maths favours casting. Design maturity is another: a part whose geometry is still changing is cheap to iterate in aluminium and expensive to iterate in hardened steel. Cash flow is the third, because casting asks for a five-figure tooling payment before the first part, and a buyer without that budget may rationally choose machining even where the long-run cost favours the die. Quality cost belongs in the model too. Compare the cost per good part rather than the cost per produced part: a casting lot with porosity on a machined face carries scrap, rework and sorting costs that no unit price shows, and a machining programme with a bad fixture carries the same burden in reverse. Ask both suppliers for their scrap and rework history alongside the price. When to choose die casting, and when not to Choose die casting above roughly 5,000 pieces a year, or from about 1,000 to 2,000 where the tooling is cheap and the part is simple. Above 20,000 pieces the advantage is large and durable. Choose CNC machining below about 500 pieces a year, and for one-offs. The tooling cannot be recovered at that volume, and the unit price gap does not exist yet. Choose a hybrid when a cast body needs two accurate features. Cast to near net shape, then machine the bores, grooves and mating faces. This is the most common real answer above 5,000 units. Do not die cast a part with deep undercuts, fine threads or a tight flatness callout. Slides and lifters can be added to the die, but each one costs several thousand dollars and adds a failure mode. Do not die cast a geometry that is still moving, or a product with a short life. Bigger up-front money needs a longer, more stable run to repay it. Do not compare a casting quote against a machining quote without loading both. Match the scope of work first, then compare the numbers. What to send for a volume-based decision Send the STEP model, the toleranced drawing, the annual volume and the expected product life, the material callout and the two or three tightest features. Those five items are enough to run the crossover arithmetic and to say whether the part is a casting, a machining job or a hybrid. See aluminium die casting for the casting route, CNC machining for the subtractive route and the die casting capability overview for tooling scope. Send a drawing and get both routes priced Scope and sources. The crossover arithmetic, the cost curves and the secondary-operation ranges come from four 2026 purchasing guides: a die casting against CNC route comparison (crossover 500 to 1,000 units, 100 pieces at about USD 220 against USD 25 machined, 10,000 pieces at about USD 4 against USD 15, 100,000 pieces at USD 1.28 million against USD 2.17 million, a heavy automotive die set near USD 750,000 amortising below USD 0.40 per part), a housing-specific comparison (break-even near 500 pieces, tooling USD 15,000 to 50,000, per-piece at 1,000 units USD 4 to 12 against USD 40 to 80, as-cast tolerance plus or minus 0.1 to 0.3 mm against plus or minus 0.005 to 0.05 mm, Ra 1.6 to 3.2 against 0.8 to 1.6 micrometres, ADC12 at 240 MPa against 6061-T6 at 310 MPa, trimming USD 0.50 to 2, deburring USD 0.50 to 3, critical-feature machining USD 5 to 30, finishing USD 2 to 10, secondary work adding 20 to 50 percent), a tooling ROI analysis (worked break-even of 1,176 units on a USD 50,000 die against a USD 45 machined part at USD 2.50 cast, cycle 60 to 90 seconds, each slider adding USD 3,000 to 8,000, bridge tooling saving 20 to 35 percent) and a die casting design and cost model (tooling USD 8,000 to 80,000, die life 100,000 to 500,000 shots, worked break-even of about 3,571 units, die casting favoured above 5,000 pieces a year and strongly favoured above 20,000). Process capability figures also draw on an OEM process benchmark (break-even 3,000 plus units a year, 1.2 to 2.5 percent gas porosity, 1.0 to 1.5 mm machining stock). Published ranges are planning inputs for 2026 and not quotations; the crossover for a specific part is calculated from that part's own die price, machining rate and feature list.

The short answer Die casting forces metal into a reusable steel die at 10 to 175 megapascals, making a part every 30 to 120 seconds at ±0.1 to 0.25 mm. Sand casting pours into a disposable sand mould under gravity and holds only ±0.5 to 1.0 mm, so it wins below 5,000 pieces and for ferrous metals. Same idea, opposite economics Both processes pour liquid metal into a cavity, and almost everything else differs. Die casting uses a hardened steel die that is reused hundreds of thousands of times and pays for itself by producing parts in seconds. Sand casting uses a pattern to form a mould that is destroyed with every part, so the tooling is cheap and the cycle is slow. That single difference explains the tolerance, the surface finish, the wall thickness and the cost curve in every row below. Read the last row first. If the part is iron, steel or copper, the other six rows do not apply. DimensionDie castingSand casting MechanismMolten metal forced in at 10 to 175 MPaPoured under gravity into a sand mould Cycle time30 to 120 seconds per shot5 to 60 minutes per part As-cast toleranceplus or minus 0.1 to 0.25 mmplus or minus 0.5 to 1.0 mm As-cast surfaceRa 1.6 to 3.2 micrometresRa 12.5 to 25 micrometres Minimum wall1.2 to 1.5 mm in aluminium3 to 5 mm ToolingUSD 20,000 to 100,000 and upUSD 500 to 5,000 for a pattern MaterialsAluminium, zinc and magnesiumNearly all castable metals Two rows deserve a second look. Cycle time is the reason the unit costs diverge so sharply at volume, because a die casting machine can produce 100 to 300 parts an hour where a sand line produces 10 to 50 parts a day. Tooling cost is the reason the divergence does not help a small programme: nobody amortises a USD 50,000 die over 800 parts. Precision, and the machining that follows it As-cast precision is the most over-quoted difference between the two processes, because the useful number is not the tolerance itself but the machining it leaves behind. A die casting is usually close enough to use on a general feature without a cut. A sand casting is not: published figures put the as-cast surface at Ra 12.5 to 25 micrometres, and the usual practice is to leave a machining allowance on every face that has to be accurate, which adds a machining operation, a fixture and a setup to the price. Tolerance is a reverse indicator, so the axis starts at zero and the tighter band sits at the top of the chart. Where a part genuinely needs the tighter band without machining, the choice is made for you: a drawing that calls for plus or minus 0.2 millimetres and a surface under Ra 6 micrometres on an as-cast face cannot be satisfied by sand casting. Where machining is planned anyway, the tolerance argument weakens considerably, and the decision returns to volume and cost. The volume arithmetic is the whole decision Published break-even volumes for the two processes cluster between 1,000 and 5,000 units a year, and the position inside that band depends on part size and complexity. A worked comparison puts a small aluminium part at USD 1,500 of pattern cost and USD 32 per part by sand casting against USD 22,000 of die cost and USD 16.20 per part by die casting, which crosses at roughly 1,300 pieces; at 10,000 pieces the die casting route saves on the order of USD 140,000. A separate estimate puts the break-even for a 1 to 10 pound part at 2,000 to 5,000 units. Size moves the number in the other direction, and this is the part small buyers miss. Large castings are penalised by die cost far more than by cycle time, so for parts of 50 pounds and up, sand casting stays cheaper even at 10,000 pieces a year and above. The bigger the part, the higher the volume needed before a die makes sense. Where each process owns the answer Sand casting owns ferrous and copper alloys. High-pressure die casting is limited to aluminium, zinc and magnesium, so a ductile iron, steel or bronze part has one route regardless of volume. Sand casting owns very large parts. It handles castings from about half a kilogram to several tonnes and can exceed several metres, well past the roughly 600 millimetre ceiling of most die casting machines. Sand casting owns low and mid volume. It is the economic choice from one piece to about 5,000 a year, and for service and legacy parts whose volume has fallen away. Sand casting owns internal cavities and undercuts. Sand cores can form internal passages that a two-part steel die cannot, because the core is broken out after the pour. Die casting owns volume aluminium and zinc. Above roughly 5,000 to 10,000 pieces a year the tooling is repaid and the unit cost advantage is three to eight times in published comparisons. Die casting owns thin walls and smooth as-cast surfaces. Walls down to 1.2 millimetres and an as-cast finish near Ra 1.6 micrometres are outside what sand casting can deliver. One honest caveat runs through both columns: neither process is porosity-free. Die casting traps gas during the fast fill, which is why pressure-tight parts often need vacuum assistance; sand casting can suffer gas, shrinkage and inclusion defects that good feeding practice reduces but does not eliminate. Either way, the defect strategy is a conversation with the foundry, not a footnote on a process name. Four questions that settle it before volume Work down the flow below in order. The first two can decide the process on their own, and only when they come out in favour of die casting does the volume arithmetic become the deciding factor. Material and size are gates rather than preferences. If either points to sand casting, the volume discussion is academic. In practice the two processes cooperate more often than they compete. Sand casting is a natural route for the prototype or bridge batch while a die is being cut, and it remains the route for service quantities long after the production die has been retired. If your part sits in the middle of the volume band, send both routes a drawing and compare fully-loaded delivered prices rather than tooling figures. See aluminium die casting for the high-volume route, the die casting capability overview for tooling scope and surface finishing for what happens after the pour. Send a drawing and get both casting routes compared Scope and sources. Process parameters and cost bands come from four published comparisons: a casting buyer guide (die tooling USD 20,000 to 100,000 and up against USD 500 to 5,000 for a pattern, per-part cost USD 1 to 10 at volume against USD 20 to 100 and up, tolerance plus or minus 0.1 to 0.25 mm against plus or minus 0.5 to 1.0 mm, surface Ra 1.6 to 3.2 against Ra 12.5 to 25 micrometres, part size 0.01 to 20 kg against 0.5 to 10,000 kg and up, 100 to 300 parts an hour against 10 to 50 a day, die life 100,000 to 500,000 parts, pattern life 500 to 2,000 uses), a sand casting cost model (pattern USD 2,000 to 20,000 against a die at USD 100,000 to 500,000 and up, cycle 5 to 60 minutes against 30 to 120 seconds, yield 40 to 70 percent against 80 to 95 percent, tolerance plus or minus 0.015 to 0.030 inch per inch against plus or minus 0.005 to 0.010, as-cast surface 250 to 500 Ra micro-inches, break-even 1,000 to 5,000 units, large castings above 50 pounds favouring sand casting beyond 10,000 units), a seven-point process comparison (cycle 30 to 90 seconds, tolerance near plus or minus 0.1 mm, Ra 1 to 2.5 micrometres, a worked break-even of about 1,300 pieces on USD 1,500 of pattern against USD 22,000 of die, and roughly USD 140,000 saved at 10,000 pieces) and a foundry perspective on volume thresholds (tolerance plus or minus 0.005 inch against plus or minus 0.030 inch, die casting volume 20,000 to 1,000,000 units against 1 to 20,000 for sand, and sand cores for internal passages). Aluminium process parameters also draw on a high-pressure die casting specification (10 to 175 MPa injection, minimum wall 1.5 mm, ISO 8062 CT4 to CT6). Figures are published planning ranges for 2026 and not quotations; the correct route for a specific part is confirmed against its own drawing and volume.

The short answer Aluminium alloy die casting injects molten aluminium into a hardened steel die under high pressure and holds it while it freezes, so one reusable die produces a near-net-shape part in seconds. Melt sits at 650 to 710 degrees, the cavity fills in 20 to 50 milliseconds, and as-cast tolerance lands near plus or minus 0.25 mm. What the process actually is Aluminium alloy die casting is a permanent-mould casting process in which molten aluminium is forced into a precision-machined steel die rather than poured into a mould that is used once. The die has two halves, a fixed cover die and a moving ejector die, clamped together by the machine at 400 to 4,000 tonnes of locking force. Molten metal is injected into the cavity under 10 to 175 megapascals, fills it in milliseconds, and is held under intensification pressure while it solidifies. The whole cycle is seconds long, which is the reason the process is economic at volume and uneconomic at one-off volumes. Three properties of the process follow from that description. The die is a master negative, so every part is geometrically identical to the first one. The fill is fast, so walls can be thin and detail fine. And because the metal freezes under pressure inside a cooled steel block, the part comes out close to final shape, which is what near-net means in practice. The four stages, and the parameters that matter Die preparation. The two H13 tool-steel halves are preheated and coated with a release agent, then clamped at 400 to 4,000 tonnes. Die surface temperature is held between 180 and 250 degrees Celsius by cooling channels in the steel; too cold and the cavity will not fill, too hot and the die wears faster. Injection. Molten alloy at 650 to 710 degrees Celsius is driven into the cavity at a gate velocity of 30 to 100 metres per second, filling it in 20 to 50 milliseconds. The shot profile is split into a slow stage that pushes metal past the gate without splashing and a fast stage that fills the part. Solidification. Intensification pressure is held for 2 to 8 seconds to squeeze out shrinkage, and the casting cools in the water-cooled die for roughly 15 to 60 seconds depending on wall thickness. This is also where most porosity is decided, because air trapped by a turbulent fill has nowhere to go. Ejection and trimming. The die opens, ejector pins push the casting out, and the shot, runners, overflows and flash are trimmed. Parts then go to deburring, machining and surface treatment as required. A 40-degree melt window either side of these bands is the difference between a full cavity and a cold shut. Typical cycle time for a complete shot is 30 to 120 seconds for automotive work, shorter for small parts and longer for thick sections. A pump or valve housing with a 3 millimetre wall commonly runs in the 25 to 38 second range. Which alloy, and why it is nearly always A380 or ADC12 Die casting alloys are not chosen for maximum strength. They are chosen for fluidity, because the metal has to fill a thin cavity before it freezes. That is why the two workhorses, A380 in North America and ADC12 in Japan, both carry 8 to 12 percent silicon: silicon raises fluidity, reduces hot tearing and lowers the melting range. The two are close relatives with different national designations and slightly different balances of copper and silicon. The differences are real but small. Pick on wall thickness, section and finish requirement rather than on the strength column. PropertyA380 (AA)ADC12 (JIS) StandardNorth America, AA designationJapan, JIS H 5302 Density2.71 g/cm32.72 g/cm3 Tensile strength310 to 345 MPa300 to 330 MPa Yield strength160 to 180 MPa150 to 170 MPa Elongation2 to 4 percent1 to 3 percent Thermal conductivity96 to 105 W per m-K90 to 100 W per m-K Heat treatable to T6NoNo Typical useAutomotive housings, coversThin-wall parts, electronics enclosures A third alloy, A356, is often mentioned alongside these two and belongs in a different conversation. It carries less silicon, holds higher strength and elongation after a T6 treatment, and is cast by gravity or low pressure rather than by high-pressure injection, because its lower fluidity does not suit a thin-wall fast fill. Where a programme needs T6 properties, the part leaves the die casting family rather than the alloy list. What a die casting can and cannot hold Wall thickness: 1.2 millimetres is achievable in a local thin section; 1.5 millimetres is the usual structural minimum; a general wall of 1.5 to 3.5 millimetres is comfortable. Below about 1 millimetre the wall becomes a process variable rather than a design input. As-cast tolerance: ISO 8062 CT4 to CT6, roughly plus or minus 0.25 millimetres on a linear dimension, with wall thickness nearer plus or minus 0.10 millimetres. Machined tolerance: plus or minus 0.05 millimetres is routine on a fixtured secondary operation, which is why accurate features are cast oversize and cut afterwards. Surface finish: Ra 1.6 to 3.2 micrometres as cast from a good die, with a denser skin layer of roughly 0.5 to 1.0 millimetres that should not be machined through. Not heat treatable: A380 and ADC12 are not suitable for T6 solution treatment, so a part that needs it must be made by gravity or low-pressure casting instead. Porosity: conventional high-pressure die casting carries 1.2 to 2.5 percent gas porosity by volume. Pressure-tight or fatigue-critical parts need vacuum assistance or squeeze casting, and that decision is made before the die is cut. Volume: tooling runs from USD 15,000 to 80,000 with a lead time of six to ten weeks, so the process is economic above roughly 3,000 to 5,000 pieces a year and uncomfortable below it. Size: most machines work within about 600 millimetres and 20 kilograms, which puts large structural castings out of scope. How to start an aluminium die casting project Send a STEP model, a toleranced drawing, the annual volume, the alloy or the property that matters most, and the surfaces that have to be accurate. Those five items let an engineer confirm the wall sections, place the parting line and tell you which features must be machined rather than cast. See aluminium die casting for the service scope, surface finishing for the options after the shot and CNC machining for the secondary operations that hold the tight dimensions. Send a model for a die casting review Scope and sources. Process stages, machine envelope, pressure, gate velocity, cycle time, wall thickness and the T6 limitation come from a 2026 high-pressure die casting specification (400 to 4,000 tonnes clamping, injection 10 to 175 MPa, melt 650 to 710 degrees Celsius, gate velocity 30 to 100 metres per second, cycle 15 to 90 seconds, minimum wall 1.5 mm, Ra 1.6 to 3.2 micrometres, ISO 8062 CT4 to CT6, A380 and ADC12 not heat treatable, tooling USD 15,000 to 80,000, economic above 5,000 pieces a year) and from a step-by-step OEM process guide (melt 660 to 700 degrees Celsius, injection 80 to 120 MPa, fill time 20 to 50 ms, holding pressure 10 to 30 ms, die temperature 180 to 220 degrees, cycle 30 to 60 seconds, as-cast tolerance plus or minus 0.05 to 0.2 mm after fixturing). Alloy properties come from an automotive alloy comparison (A380 against ADC12 on density 2.71 and 2.72 g/cm3, tensile 310 to 345 and 300 to 330 MPa, yield 160 to 180 and 150 to 170 MPa, elongation 2 to 4 and 1 to 3 percent, thermal conductivity 96 to 105 and 90 to 100 W per metre-kelvin, melting range 555 to 595 degrees, linear tolerance near plus or minus 0.25 mm, flatness 0.30 mm per 100 mm, wall thickness plus or minus 0.10 mm, injection 40 to 120 MPa with intensification 60 to 150 MPa, cycle 30 to 120 seconds). The A356 caveat and the tooling and die-life figures come from a die casting design and cost guideline (A356 at 310 MPa tensile and 5 to 10 percent elongation after T6, used in gravity and low-pressure casting rather than high-pressure injection, tooling USD 8,000 to 80,000, die life 100,000 to 500,000 shots). Porosity, machining stock and skin depth come from an OEM process benchmark (gate velocity near 42 metres per second giving 1.2 to 2.5 percent gas porosity, 1.0 to 1.5 mm machining stock, dense skin 0.5 to 1.0 mm). Figures are published planning ranges for 2026, not quotations, and the alloy and process for a specific part are confirmed against its own drawing.

The short answer Zinc alloy die casting injects molten Zamak into a steel die on a hot-chamber machine, where the gooseneck sits in the melt. Zinc pours at 380 to 430 degrees Celsius, roughly 250 degrees cooler than aluminium, so dies last 500,000 to 1,000,000 shots, cycles run in seconds and walls go down to 0.5 mm. What the process is, and why it is a hot-chamber process Zinc alloy die casting is the permanent-mould casting of zinc-based alloys, almost always the Zamak family, by injecting molten metal into a hardened steel die at high pressure. Its defining feature is that it is run on a hot-chamber machine: the injection cylinder and gooseneck are immersed in the melt, so the metal is transferred from a bath a few centimetres away rather than ladled into a cold shot sleeve. That is only possible because zinc does not attack iron the way aluminium does, and it is the reason the process is so much faster and gentler than its aluminium cousin. The whole cycle is measured in seconds, and the melt bath is part of the machine rather than a separate furnace. The practical consequences stack up. Melt temperature is 380 to 430 degrees Celsius against 660 to 720 for aluminium, so the die sees far less thermal shock and far less heat checking. Injection pressure is a fraction of the aluminium figure, at roughly 15 to 40 megapascals, so gates and runners erode more slowly. And because cooling is quick, published cycle times for small zinc parts run at 2 to 6 seconds per shot against 4 to 12 seconds for cold-chamber aluminium. What the lower temperature buys: die life and tolerance Die life is where zinc separates itself most clearly from aluminium. A well-maintained zinc die commonly exceeds 1,000,000 shots before major refurbishment, against 150,000 to 300,000 for aluminium on the same geometry. Because the die holds its dimensions for far longer, tolerances stay tight for a greater share of the tool's life, and published figures put zinc die casting at plus or minus 0.03 to 0.05 millimetres on small parts without any secondary machining. A die polished to a fine cosmetic finish reproduces an as-cast surface near Ra 0.2 to 0.4 micrometres, which is why zinc hardware often goes straight from the die to the plating line. Every bar is the same measurement, so the comparison holds across the row. Tool life is the reason the zinc route sometimes undercuts aluminium on total programme cost despite a denser material. Wall thickness follows the same logic. Zinc is more fluid than aluminium and freezes over a narrower range, so the practical minimum falls to about 0.5 millimetres on small cosmetic parts, 1.0 millimetre as a general engineering floor, and 1.5 millimetres where the part carries load or holds a thread. Maximum uniform wall should stay under about 4 millimetres to avoid centre-line shrinkage, and draft angles can be small, around 0.5 to 1.0 degrees on outside faces and 1.0 to 1.5 degrees inside, because zinc shrinks only 0.6 to 0.8 percent. The Zamak family, and what the copper buys Zamak stands for zinc, aluminium, magnesium and copper, and the letter grade is essentially a statement about how much copper is in the mix. Zamak 3 is the baseline and accounts for the large majority of general zinc castings: 4 percent aluminium, no deliberate copper addition, 283 megapascals tensile and around 10 percent elongation, which makes it ductile enough for clinching, riveting and snap fits. Zamak 5 adds roughly 1 percent copper, which raises tensile strength to about 328 megapascals and hardness to around 91 Brinell at the cost of elongation, which falls to 5 to 7 percent; it is the grade chosen for latches, hinges and parts under repeated mechanical load. Zamak 2 pushes copper to 2.5 to 3 percent and reaches 360 to 400 megapascals with 3 to 5 percent elongation, for the highest-strength work a hot-chamber machine can handle. Read the elongation column alongside the strength column. The grade that is strongest is also the one least able to bend. A fourth family, the ZA grades, sits outside this table. ZA-8 contains more aluminium and can still run on hot-chamber equipment, while ZA-12 and ZA-27 pour hot enough that they destroy the gooseneck and are restricted to cold-chamber machines. They are specified for bearing and wear duty rather than for the general hardware that Zamak covers. Where zinc die casting is the wrong choice Weight matters and the part is large. Zinc has a density of 6.6 to 6.8 grams per cubic centimetre, more than twice aluminium's 2.7. Below a few hundred grams the penalty is irrelevant; above it, the same part in aluminium or magnesium is lighter and cheaper to move. The part runs hot or carries sustained load. Zinc creeps under load at elevated temperature, which is exactly why Zamak 5 exists alongside Zamak 3. Where a part sits in a hot or continuously loaded location, the service temperature is checked against the alloy datasheet before zinc is specified, and the grade is chosen for creep rather than for strength. The programme is small. Zinc dies are long-lived and correspondingly expensive to cut, so the route needs volume to repay the tooling just as aluminium does. The surface has to be bare metal for an anodised finish. Zinc does not anodise the way aluminium does; the usual route is electroplating, typically a copper-nickel-chrome stack around 25 micrometres thick that passes salt-spray testing for 96 hours. The casting has to be pressure tight or structural in a high-integrity sense. Zinc keeps good properties in thin sections, but where a specification calls for a qualified structural casting the material and process are confirmed per programme in writing rather than assumed. How to start a zinc die casting project Send a STEP model, a toleranced drawing, the annual volume, the finish you need and the environment the part will see. Those five items decide the grade, the wall sections and whether the part goes to the plating line or comes off the die as finished. Zinc is usually the right answer for small, detailed, moderately loaded hardware that has to look good and hold a thread; aluminium is usually the right answer once the part grows or has to be light. See aluminium die casting for the comparison, the die casting capability overview for tooling scope and surface finishing for plating and coating options. Send a model for a zinc die casting review Scope and sources. Process temperatures, cycle times, clamp force, die materials and wall-thickness gates come from a zinc die casting selection guide (Zamak 3 at about 420 degrees Celsius and 280 MPa, Zamak 5 at about 420 degrees and 330 MPa, Zamak 2 at about 420 degrees and 360 MPa, hot-chamber machines 20 to 160 tonnes, cycle 2 to 6 seconds against 4 to 12 for cold-chamber aluminium, die life 200,000 to 500,000 shots against 80,000 to 150,000 for aluminium, minimum tolerance 0.03 to 0.05 mm, wall minimum 0.8 mm cosmetic and 1.0 mm general with 1.5 mm under load, SPI A-1 and A-2 die finishes giving Ra 0.2 to 0.4 micrometres, ZA-12 and ZA-27 restricted to cold-chamber machines) and from a zinc die casting design reference (melt 380 to 430 degrees Celsius against 660 to 720 for aluminium, die life 1,000,000 to 3,000,000 shots against 100,000 to 500,000, thin wall 0.8 to 1.5 mm, standard wall 1.5 to 3 mm, rib thickness 50 to 70 percent of wall, draft 0.5 to 2 degrees). Alloy properties and process parameters for the Zamak grades come from a Zamak comparison (tensile 283, 328 and 400 MPa, elongation 10, 5 to 7 and 3 to 5 percent, hardness 82, 88 and 100 HB, density 6.6, 6.7 and 6.8 g/cm3, melting range 381 to 387, 380 to 389 and 379 to 393 degrees Celsius, die temperature 80 to 120 degrees, injection 15 to 35 MPa for Zamak 3, hot-chamber machinery, a copper-nickel-chrome plating stack at 25 micrometres passing 96 hours of salt spray, and zinc dies not needing nitriding so costing about 20 percent less to build). Die life, tolerance, hardness and creep context also draw on a zinc die casting automotive guide (Zamak 5 at 328 MPa tensile, 228 MPa yield, 91 Brinell, about 7 percent elongation, 96 GPa modulus, zinc dies above 1,000,000 shots against 100,000 to 300,000 for aluminium, tolerances near plus or minus 0.025 mm) and on a 2026 zinc alloy materials comparison (melt 380 to 390 degrees Celsius against 580 to 660 for aluminium, tolerance to plus or minus 0.05 mm without secondary machining, tool life 500,000 to 1,000,000 shots, wall down to 0.5 mm, cooling 15 to 25 percent faster, density 6.6 g/cm3 against 2.7 for aluminium, tensile 280 to 350 MPa against 200 to 320 MPa). Figures are published planning ranges for 2026 and not quotations; the alloy and process for a specific part are confirmed against its own drawing and service conditions.