Die Casting Services: Aluminium, Zinc & Magnesium Components Built to Production Tolerances
Choosing a Casting Partner Means Choosing a Process Portfolio
Most component enquiries arrive already committed to a process. The drawing says "Die Cast", the alloy is named, and the buyer wants a price.
But the same functional requirement frequently has a better route. A small intricate connector quoted as conventional Aluminium Die Casting may cost far less in zinc on a multi-slide machine. A structural bracket demanding T6 properties cannot be produced by conventional high-pressure casting at all — the physics prevent it. A thick-walled housing at 800 units per year will never amortise a hardened production die.
A supplier running only one process will fit your part to that process. Our Die Casting Services span cold chamber, hot chamber and multi-slide technologies across aluminium, zinc and magnesium, with in-house tooling, machining and finishing — so the recommendation follows the part rather than the equipment we happen to own.
Capabilities Summary
| Capability | Specification |
|---|---|
| Clamp force | 160 – 3,500 tons |
| Technologies | Cold chamber · Hot chamber · Multi-slide |
| Alloys | Aluminium · Zinc · Magnesium |
| Part weight | 10 g – 40 kg |
| Tolerance, as-cast | ±0.10 mm per 25 mm (NADCA) |
| Tolerance, machined | ±0.02 mm |
| Minimum wall — aluminium | 1.2 mm |
| Minimum wall — zinc | 0.4 mm |
| Minimum wall — magnesium | 1.2 mm |
| Surface roughness, as-cast | Ra 1.6 – 3.2 µm |
| Die life — aluminium | 200,000 – 350,000 shots |
| Die life — zinc | 500,000 – 1,000,000 shots |
| Tooling lead time | 5 – 8 weeks (bridge tooling 3 – 5 weeks) |
| MOQ | 500 – 1,000 pcs once tooling exists |
| Certification | ISO 9001:2015 · IATF 16949 |
The 3,500-ton upper range matters for a specific reason: clamp force is dictated by projected area, not part weight. Aluminium requires roughly 2–4 tons per square inch of projected area including the runner system. A large structural housing with 600 in² projected area needs 1,200–2,400 tons regardless of how light it is.
Three Casting Technologies
Cold Chamber — Aluminium and Magnesium
The shot sleeve sits outside the melt. An automatic ladler transfers a metered charge each cycle, then a hydraulic plunger injects at 700–1,200 bar, filling the cavity in milliseconds.
The separation is not optional. Molten aluminium at 660°C chemically attacks submerged ferrous components, dissolving them within hours and driving iron content above the 0.9% limit most structural specifications allow. Any supplier claiming hot chamber aluminium production has misunderstood the process.
Suits: housings, gearbox covers, structural brackets, Heat Sinks, enclosures from 100 g upward.
Hot Chamber — Zinc
The gooseneck injection system sits submerged directly in the zinc pot. Zinc's 385–400°C working temperature is gentle enough that submerged hardware survives, and eliminating the ladling step removes several seconds per cycle.
Suits: locks, hinges, connectors, decorative hardware, precision mechanisms.
Multi-Slide — Small Complex Zinc Parts
Instead of two die halves opening along one axis, four or more slides close inward from independent directions. Features that would demand side actions in a conventional die form naturally, cycle times drop below two seconds, and tooling wear is spread across more surfaces.
Suits: small intricate zinc components under roughly 100 g, particularly those with features on multiple faces. Where a conventional die would need three side actions, multi-slide often eliminates all of them.
Alloy Selection
Aluminium
| Alloy | Characteristics | Typical Use |
|---|---|---|
| A380 / ADC10 | Best all-round castability, strength and machinability | Housings, gearboxes, enclosures |
| A383 / ADC12 | Higher fluidity than A380 for intricate geometry | Complex thin-wall parts |
| A360 | Superior corrosion resistance, higher ductility | Marine and outdoor equipment |
| A413 | Highest fluidity, excellent pressure tightness | Manifolds, hydraulic bodies |
| B390 | Hypereutectic, high hardness and wear resistance | Cylinder liners, pump components |
| EN AC-46000 / AlSi9Cu3 | European standard equivalent to A380 family | EU automotive supply |
Zinc and Magnesium
- ZAMAK 3 / 5 — walls to 0.4 mm, plating-ready as-cast surface, exceptional tool life.
- AZ91D / AM60B — lowest density at 1.8 g/cm³, natural EMI shielding, used for handheld device housings.
Two Points We Raise Before Tooling
A380 does not anodise bright. Its 3–4% copper content produces a mottled dark grey film rather than clean silver. Where bright anodised appearance is required, we specify A360 or A413 at design stage, because changing alloy after tooling is cut may force gate and thermal re-engineering.
Wrought alloys cannot be cast. 6061 and 6063 carry only 0.4–0.8% silicon, giving poor fluidity and a wide freezing range that hot-tears in a steel die. A drawing specifying 6061-T6 needs CNC machining from billet or aluminum fabrication from extruded profile. We flag this at quotation rather than substituting A356 silently — they behave differently.
The T6 Constraint Most Suppliers Do Not Mention
This single limitation reshapes more programmes than any other, and it appears on almost no capability page.
Conventional high-pressure die casting fills at 30–60 m/s. That velocity is inherently turbulent — the metal front fragments and entrains atmospheric air plus vaporised die lubricant, leaving dispersed high-pressure gas pores through the section.
At room temperature those pores are inert. But T6 requires a solution soak at 500–540°C. The trapped gas expands sharply while the surrounding aluminium softens toward its solidus, lifting the skin into dome-shaped surface blisters that cannot be repaired.
| Requirement | Viable Route |
|---|---|
| Thin wall, high volume, as-cast properties | Cold chamber HPDC, T5 ageing only |
| T6 properties, moderate volume | Gravity or low-pressure casting in A356 |
| T6 properties, thin wall | Vacuum-assisted HPDC with section limits |
| Maximum as-cast strength | HPDC — finest microstructure of any casting route |
The conversation worth having early: does the design genuinely need 200+ MPa yield, or was T6 inherited from a machined-part drawing? As-cast A380 delivers roughly 160 MPa and is frequently adequate — and dramatically cheaper.
Secondary Operations and Finishing
Precision machining — bores, threaded ports, sealing faces and datums to ±0.02 mm. Threads are always machined rather than cast, because cast threads rarely reach the surface finish required for reliable sealing.
| Process | Build | Primary Benefit |
|---|---|---|
| Shot / bead blasting | — | Uniform matte texture, deflashing |
| Chemical conversion (Cr³⁺) | 0.5–2 µm | Corrosion protection, electrically conductive |
| Anodising Type II | 5–25 µm | Corrosion and wear resistance, colour |
| Hard anodise Type III | 25–100 µm | Severe wear surfaces |
| Powder coating | 60–120 µm | Colour, UV and impact resistance |
| E-coat | 15–35 µm | Uniform coverage into recesses |
| Plating (Ni / Cr) | 5–25 µm | Bright decorative finish, best on zinc casting |
Two specification details that cause assembly failures:
Anodising insulates; chemical film conducts. If a die cast housing relies on a bolted joint for chassis ground or wall continuity for EMI shielding, a fully anodised part breaks that path. We mask grounding pads or treat them with chemical film only, recorded as a defined zone with a stated resistance limit.
Coating consumes clearance. Anodising grows roughly half into the substrate and half outward, so 25 µm hard anodise reduces a bore by around 25 µm. Powder coat at 60–120 µm is far more severe and builds unevenly on edges. State on the drawing whether dimensions apply before or after coating.
Assembly — threaded inserts, helicoils, press-fit bearings, seals, sub-assembly build and functional test.
Metal fabrication — laser cutting, CNC press brake forming, TIG and MIG welding. Many products are best built as hybrids: a cast body carrying the complex sealed geometry with custom metal fabrication brackets attached. This often removes two side actions from the die. Because both routes run in-house, tolerance stack-up between cast and fabricated components is engineered by one team rather than disputed between two suppliers. For low-volume structural fabrication — frames, chassis, panels — no tooling is required and parts ship in one to three weeks.
Engineering Support Before Tooling
Roughly 70% of a component's lifetime cost is committed during design while only about 8% has been spent. Every quotation therefore returns DFM feedback — a supplier who quotes without comment has priced in the problems they can see and stayed silent.
What we review on every drawing:
- Wall thickness: ●— 2.0–3.0 mm nominal for aluminium, variation kept within a 1:3 ratio. Solidification time scales with the square of section thickness, so reducing 4 mm to 2.8 mm cuts cooling time to roughly half.
- Wall transitions: ●— tapered over at least 3× the thickness difference. Abrupt steps create isolated thermal mass that gates cannot feed once frozen.
- Draft angle: ●— 1° external minimum, 1.5–2° internal. Internal surfaces need more because the casting shrinks onto cores during cooling.
- Fillet radius: ●— at least 1× the adjoining wall. Sharp internal corners concentrate stress in the part and initiate heat-checking cracks in the die steel.
- Boss design: ●— outer diameter within 2.5× the adjoining wall, or cored out. Oversized solid bosses shrink internally, producing porosity or a visible sink mark opposite.
- Side actions: ●— each undercut requiring a slide adds tooling cost, cycle time and a maintenance point. We identify every one and propose alternatives.
Mould flow simulation runs before steel is cut, predicting fill sequence, air entrapment zones and shrinkage-risk regions. Used this way it is a design tool. A supplier running simulation only after a failed T1 trial is using it as a diagnostic — and charging you for the difference.
Quality Assurance
Certification: ISO 9001:2015 · IATF 16949. PPAP Level 3 submissions including FMEA, control plan, MSA and capability study.
Five inspection gates:
- 1
Incoming material: — optical emission spectrometry verifies alloy chemistry per heat before charging, cross-checked against the mill certificate.
- 2
First article: — full-dimension FAI with actual measured values and the instrument identified per feature.
- 3
In-process: — shot velocity, intensification pressure and fill time captured every cycle against the qualified window, with automatic quarantine of out-of-window parts. SPC on critical dimensions targeting Cpk ≥ 1.33.
- 4
Final: — CMM verification against GD&T, X-ray to ASTM E505 with drawing zone map, and leak testing at rated pressure where specified.
- 5
Outgoing: — document package assembled: material certificate per heat, dimensional report with actual values, treatment records, NDT results, and packing list with lot traceability to heat number and production date.
Porosity control. Two distinct defects need two distinct remedies. Gas porosity — rounded dispersed pores from entrained air and lubricant vapour — is controlled by vacuum assist, evacuating the cavity below 50 mbar before injection and cutting gas porosity 60–80%. Shrinkage porosity — irregular voids where gates freeze before heavy sections solidify — is controlled by local squeeze pins driven into the semi-solid section, or eliminated at DFM by coring out the thermal mass. Pressure-tight parts require both.
Industries Served
- Automotive and EV — motor housings, gearbox covers, oil pans, structural brackets, battery enclosure components. PPAP, SPC and 100% leak testing as standard.
- Enterprise technology and data centre — server chassis components, thermal management housings, heat sinks where fin geometry and coating choice determine performance.
- Consumer electronics — enclosures, internal frames, connectors. EMI shielding depends on wall continuity and conductive grounding paths.
- Medical devices — instrument housings and enclosures with clean surface finish and full material traceability.
- Industrial machinery — pump bodies, valve housings, gear cases, actuator bodies, precision brackets.
- Hardware and fluid handling — locks, hinges, fittings and manifolds. For pipe fittings manufacturer requirements, threads are machined post-cast and radiographic acceptance is specified per ASTM E505 with a zone map.
Frequently Asked Questions
As-cast aluminium holds approximately ±0.10 mm per 25 mm within one die half, widening to ±0.25 mm across the parting line, per NADCA Product Standards. Post-cast CNC machining reaches ±0.02 mm. Treat claims of ±0.01 mm as casting tolerance with caution — that figure belongs to secondary machining. Apply tight tolerances only to critical-to-function features; a drawing with ±0.05 mm everywhere forces machining of every surface and can double piece price.
Alloy decides first. Aluminium and magnesium require cold chamber because molten aluminium at 660°C dissolves submerged ferrous injection hardware. Zinc runs hot chamber, which is faster because it eliminates the ladling step. For small intricate zinc parts under roughly 100 g with features on multiple faces, multi-slide closes four or more slides from independent directions, forming undercuts that would need side actions in a conventional die while cycling under two seconds.
Conventional high-pressure die castings generally cannot. The 30–60 m/s fill entrains gas as dispersed high-pressure pores; a T6 solution soak at 500–540°C expands that gas while the aluminium softens, lifting the surface into unrepairable blisters. HPDC parts are supplied as-cast or T5 aged. For genuine T6 properties, we route the part to gravity or low-pressure casting in A356, or vacuum-assisted HPDC with section thickness limits.
Aluminium at 2.7 g/cm³ suits structural parts, thermal management and service above 100°C — the default for housings and enclosures. Zinc casting suits small detailed parts under roughly 500 g needing walls below 1 mm or decorative plating, with 500,000–1,000,000 shot tool life against aluminium's 200,000–350,000. Magnesium at 1.8 g/cm³ is lightest with natural EMI shielding, used for handheld devices, but costs more per kilogram and requires coating for corrosion resistance.
Batches from 500–1,000 pieces are practical once tooling exists, though custom die casting typically becomes cost-competitive above 5,000 pieces per year because the binding constraint is tooling amortisation rather than batch size. A single-cavity aluminium tool takes 5–8 weeks from approved drawing to T1 samples. For validation or lower volumes, bridge tooling in P20 steel gives 5,000–20,000 shots in 3–5 weeks at substantially lower upfront cost.
By addressing two mechanisms separately. Gas porosity is controlled with vacuum assist, evacuating the cavity below 50 mbar before injection to remove air and lubricant vapour, reducing gas porosity 60–80%. Shrinkage porosity is controlled with local squeeze pins driven into heavy sections while the metal is semi-solid, or eliminated at DFM by coring out isolated thermal mass. Pressure-tight parts use both, plus A413 alloy for its natural pressure tightness and 100% leak testing at rated pressure.
Yes. CNC machining, all major surface finishing processes, insert installation, leak testing and assembly run under the same quality system as casting. We also provide metal fabrication — laser cutting, press brake forming and welding — enabling hybrid assemblies. Keeping both routes in-house removes the situation where a foundry and a machine shop each blame the other for a fit problem at final assembly.