Custom Die Casting Services: Aluminium, Zinc & Magnesium Parts from Tooling to Delivery
Everything After the Casting Machine Is Where Programmes Succeed or Fail
Injecting molten metal into a steel die is the easy part. Any competent foundry can do it.
What separates a supplier who delivers on schedule from one who consumes your engineering time is everything wrapped around that operation — whether the DFM review happens before tooling or after a failed trial, whether shot parameters are recorded per cycle or trusted to the operator, whether machining and finishing run in-house or get subcontracted across three towns.
Our die casting services cover the complete chain: free DFM analysis with every quotation, mould flow simulation before steel is cut, in-house tooling, cold and hot chamber production, CNC machining, Surface Finishing, inspection and assembly. One contract, one engineer, one organisation accountable.
Capabilities at a Glance
| Capability | Specification |
| Clamp force range | 250 – 1,600 tons |
| Processes | Cold chamber · Hot chamber · Semi-solid |
| Alloys | Aluminium · Zinc · Magnesium |
| Part weight | 20 g – 25 kg |
| Tolerance, as-cast | ±0.10 mm per 25 mm |
| Tolerance, machined | ±0.02 mm |
| Minimum wall — aluminium | 1.2 mm (2.0–3.0 mm recommended) |
| Minimum wall — zinc | 0.4 mm |
| Wall thickness ratio | Keep within 1:3 across the part |
| Draft angle | 1° external · 1.5–2° internal |
| Cast hole diameter | ⌀3 mm minimum; smaller holes drilled |
| Die life — aluminium | 200,000 – 350,000 shots |
| Die life — zinc | 500,000 – 1,000,000 shots |
| MOQ | 500 – 1,000 pcs once tooling exists |
| Tooling lead time | 5–8 weeks (bridge tooling 3–5 weeks) |
| Certification | ISO 9001:2015 · IATF 16949 · ISO 13485 |
A note on the tolerance figure. Claims of ±0.01 mm on Die Castings are misleading — that precision belongs to secondary machining, not to the casting operation. As-cast aluminium holds ±0.10 mm per 25 mm per NADCA Product Standards, widening across the parting line. We quote both figures separately so you know which features need machining and which do not.
Three Die Casting Processes and When Each Applies
Cold Chamber — Aluminium and Magnesium
The shot sleeve sits outside the melt. A dosing ladle transfers a metered charge each cycle, then a hydraulic plunger injects it at 700–1,200 bar.
This separation is not a design preference — it is mandatory for aluminium. At 660°C, molten aluminium chemically attacks and dissolves submerged ferrous components within hours. A hot chamber system running aluminium would destroy its own injection hardware and contaminate the alloy with iron above the 0.9% limit that most structural specifications allow.
Applications: engine and motor housings, gearbox covers, structural brackets, electronics enclosures, Heat Sinks.
Hot Chamber — Zinc
The gooseneck injection system sits submerged in the molten zinc pot, feeding metal directly into the die. Eliminating the ladling step cuts several seconds per cycle, and zinc's 385–400°C working temperature is gentle enough that submerged hardware survives.
Applications: locks and hardware, connectors, decorative trim, small precision mechanisms.
Semi-Solid — Low Porosity Requirements
Metal is brought to a thixotropic slurry state — partly solid, partly liquid — and injected with laminar rather than turbulent flow. Less turbulence means far less entrained gas, so semi-solid parts reach lower porosity and can accept heat treatment that conventional high-pressure castings cannot.
Applications: pressure-tight housings, structural components requiring T6 properties, safety-critical parts.
Alloys We Run
Aluminium
| Alloy | Si % | Cu % | Characteristics | Typical Use |
| A380 / ADC10 | 7.5–9.5 | 3.0–4.0 | Best all-round castability and machinability | Housings, gearboxes, enclosures |
| A360 | 9.0–10.0 | ≤0.6 | Superior corrosion resistance | Marine, outdoor equipment |
| A413 / ADC12 | 11.0–13.0 | ≤1.0 | Highest fluidity, pressure-tight | Manifolds, hydraulic bodies |
| A356 (T6 capable) | 6.5–7.5 | ≤0.25 | Heat treatable to 200+ MPa yield | Structural components |
Zinc and Magnesium
ZAMAK 3 / 5 / ZA-8 — 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 Alloy Facts We Raise at Quotation
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. If your drawing specifies 6061-T6, that part needs CNC machining from billet or aluminum fabrication from extruded profile. We flag this rather than substituting A356 silently — they are different materials with different properties.
A380 does not anodise bright. Its copper content produces a mottled dark grey film. Where bright anodised appearance matters, we specify A360 or A413 during design, because changing alloy after tooling is cut may require gate and thermal re-engineering.
Design for Manufacturability — Included, Not Extra
Alt text: Die casting design rules infographic showing uniform wall thickness, draft angle, fillet radius versus sharp corner, cored boss with connecting ribs and rib width proportion
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 — not because it is a marketing gesture, but because a supplier who quotes a drawing without comment has priced in the problems they can see and stayed silent about them.
What we check on every drawing:
Wall thickness — target 2.0–3.0 mm nominal for aluminium, with variation across the part kept within a 1:3 ratio. Solidification time scales with the square of section thickness, so reducing a 4 mm wall to 2.8 mm cuts cooling time to roughly half and removes about 25% of material mass.
Wall transitions — tapered over at least three times the thickness difference. Abrupt steps create isolated thermal mass that gates cannot feed once they freeze, which is the direct mechanism of shrinkage porosity.
Draft angle — 1° external minimum, 1.5–2° internal. Internal surfaces need more because the casting shrinks onto cores as it cools, increasing extraction friction.
Fillet radius — at least 1× the adjoining wall thickness. Sharp internal corners concentrate stress in the part, concentrate heat during solidification, and initiate heat-checking cracks in the die steel.
Boss design — outer diameter no more than 2.5× the adjoining wall, or cored out. Solid oversized bosses shrink internally, producing either sub-surface porosity or a visible sink mark on the opposite face.
Side actions — every undercut requiring a slide adds tooling cost, cycle time and a maintenance point. We identify each one and propose alternatives: re-orienting the feature, moving it to the parting line, or machining it post-cast.
Surface Finishing
| Process | Build | Primary Benefit |
| As-cast | — | Functional surfaces, non-cosmetic applications |
| Shot / sand blasting | — | Uniform matte texture, coating adhesion |
| 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 points that cause assembly failures:
Anodising insulates; chemical film conducts. If a die cast housing relies on a bolted joint for chassis ground or on wall continuity for EMI shielding, a fully anodised part breaks that path. We mask grounding pads or treat them with chemical film only, recorded on the drawing 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, concentrating on edges. State on the drawing whether dimensions apply before or after coating; we mask precision bores and ream them last.
Quality Assurance
Certification: ISO 9001:2015 · IATF 16949 (automotive) · ISO 13485 (medical). PPAP Level 3 submissions including FMEA, control plan, MSA and capability study.
Inspection at Five 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, not "OK" ticks.
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-to-function dimensions targeting Cpk ≥ 1.33.
4 · Final — CMM verification against GD&T, X-ray to ASTM E505 with drawing zone map, dye penetrant, 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.
We treat the document package as a delivery condition rather than a courtesy, because once parts ship it is the only enforceable record either party holds.
Porosity Control
Two distinct defects require two distinct remedies, and suppliers who conflate them solve neither:
Gas porosity — rounded, dispersed pores from air and lubricant vapour entrained during the 30–60 m/s fill. Controlled by vacuum assist, evacuating the cavity below 50 mbar before injection, cutting gas porosity 60–80%.
Shrinkage porosity — irregular voids in heavy sections where gates freeze before the thick mass solidifies. Controlled by local squeeze pins driven into the semi-solid section, or by gate and geometry redesign.
For pressure-tight parts, both are prerequisites, not upgrades.
Industries Served
Automotive and EV — motor housings, gearbox covers, oil pans, structural brackets, battery enclosure components. PPAP, SPC and 100% leak testing as standard.
Consumer electronics — enclosures, internal frames, connectors, heat sinks. EMI shielding depends on wall continuity and conductive grounding paths.
Lighting — LED street light and high-bay housings, heat sinks. Thermal performance depends on fin geometry and coating choice; thick powder coat insulates, thin black anodise raises emissivity.
Medical devices — instrument housings and enclosures under ISO 13485, with clean surface finish and full traceability.
Industrial machinery and robotics — pump bodies, valve housings, gear cases, actuator bodies, precision brackets.
Fluid handling — manifolds, elbows and flange adapters. For pipe fittings manufacturer requirements, threads are machined post-cast because cast threads rarely achieve reliable sealing finish.
Beyond Casting
CNC machining — bores, threaded ports, sealing faces and datums to ±0.02 mm. Heat treatment — T5 ageing for die castings; full T6 on gravity-cast A356 and semi-solid parts. 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.
That last capability changes what is possible at design stage. Many products are best built as hybrids — a cast body carrying the complex sealed geometry with custom metal fabrication brackets attached for mounting. Splitting the work this way 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 needed and parts ship in one to three weeks.
Frequently Asked Questions
Q1: What tolerances can die casting actually achieve?
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. Be cautious of suppliers quoting ±0.01 mm as a casting tolerance — that figure belongs to secondary machining. We quote both separately so you know which features require 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.
Q2: What is the minimum order quantity and how long does tooling take?
Once tooling exists, batches from 500–1,000 pieces are practical, though custom die casting typically becomes cost-competitive above 5,000 pieces per year because the binding constraint is tooling amortisation. 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.
Q3: How do you minimise porosity in die cast parts?
By treating the two mechanisms separately. Gas porosity — rounded pores from air and lubricant vapour entrained during high-velocity fill — is controlled with vacuum assist, evacuating the cavity below 50 mbar before injection and reducing gas porosity by 60–80%. Shrinkage porosity — irregular voids in heavy sections isolated when gates freeze — is controlled with local squeeze pins driven into the semi-solid section, or eliminated at DFM by coring out the thermal mass. Pressure-tight parts use both, plus 100% leak testing.
Q4: Should I choose aluminium, zinc or magnesium?
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 requiring 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 the lightest option with natural EMI shielding, used for handheld devices, but costs more per kilogram and needs coating for corrosion resistance.
Q5: Can die castings be heat treated to T6?
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. Where genuine T6 properties are required, we route the part to semi-solid casting, gravity permanent mould in A356, or vacuum-assisted HPDC with section thickness limits.
Q6: What should I consider when designing for die casting?
Six points. Keep nominal wall at 2.0–3.0 mm with variation within a 1:3 ratio and transitions tapered over at least three times the thickness difference. Apply 1° draft externally and 1.5–2° internally. Use internal fillets of at least 1× wall thickness — never zero-radius corners. Keep boss diameter within 2.5× the adjoining wall or core it out. Discuss gate and parting line placement before tooling, since relocating them afterwards means welding and re-cutting the cavity. Justify or eliminate every side action.
Q7: Do you handle machining and finishing in-house?
Yes. CNC machining, heat treatment, 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.