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High Pressure Die Casting-1

Aluminium Casting · Creative Alucast

High Pressure Die Casting

Thinnest Walls, Finest Finish, Highest Volumes

Tolerance: DCTG 6–9

Surface: Ra 0.8–3.2 µm

ISO 9001:2015

Process at a Glance Table - Centered
Process at a Glance
Tolerance grade DCTG 6-9
Surface finish Ra 0.8-3.2 μm
Min wall thickness 1.0-2.0mm – thinnest of all casting processes
Draft (external) 0.5° min – finest draft of all processes
MA per face 0.5-1.0mm per face
Tolerance standard ISO 8062-3:2007

High Pressure Die Casting

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Aluminium Casting · Creative Alucast

High Pressure Die Casting

Thinnest Walls, Finest Finish, Highest Volumes

  • Tolerance: DCTG 6–9
  • Surface: Ra 0.8–3.2 µm
  • ISO 9001:2015
Process at a Glance Table - Centered
Process at a Glance
Tolerance grade DCTG 6-9
Surface finish Ra 0.8-3.2 μm
Min wall thickness 1.0-2.0mm – thinnest of all casting processes
Draft (external) 0.5° min – finest draft of all processes
MA per face 0.5-1.0mm per face
Tolerance standard ISO 8062-3:2007

HPDC Reference Image

High-quality image of HPDC equipment or HPDC aluminium castings — thin-wall automotive
housing, electronic enclosure, or complex HPDC component showing the fine as-cast surface finish and
dimensional precision achievable with high-pressure die casting.

Overview

Thinnest Walls, Finest Finish, Highest Volumes

High Pressure Die Casting (HPDC) is the fastest aluminium casting process, injecting molten metal into a hardened steel die at pressures of 700–1,200 bar in milliseconds. The result is the thinnest achievable walls (1.0–2.0mm), the finest as-cast surface finish (Ra 0.8–3.2 µm), and the tightest dimensional tolerances (DCTG 6–9) of any casting process — making HPDC the dominant process for high-volume automotive, electronics, and consumer product applications.

The trade-off for these advantages is inherent gas porosity from the high-velocity turbulent fill — entrapped air cannot escape in the millisecond fill time, leaving micro-porosity throughout the casting. This means HPDC castings are generally not heat-treatable to T6 (gas expansion during solution treatment causes surface blistering), and alloy choice is restricted to LM2, LM20, and LM24 — alloys formulated specifically for HPDC with higher iron content to prevent die soldering.

Creative Alucast & High Pressure Die Casting

High Pressure Die Casting requires cold-chamber machines for aluminium. For HPDC enquiries and requirements, contact our engineering team — we are well-versed in HPDC design rules, alloy selection, and process parameters, and can provide technical guidance on HPDC feasibility, tooling design, and alloy specification. Our GDC and LPDC processes are often strong alternatives to HPDC for lower volumes or when T6 heat treatment is required.

Process Comparison

Where High Pressure Die Casting sits relative to the other aluminium casting processes:

Sand Casting

DCTG 11–14
Ra 6.3–25 µm
Min wall 3–5mm
Tooling: Lowest

Tilt GDC

DCTG 8–12
Ra 3.2–12.5 µm
Min wall 3–4mm
Tooling: Medium

LPDC

DCTG 7–11
Ra 1.6–6.3 µm
Min wall 3–4mm
Tooling: Med–High

HPDC

DCTG 6–9
Ra 0.8–3.2 µm
Min wall 1–2mm
Tooling: Highest

HPDC Process Reference

Reference image of HPDC production environment — row of HPDC machines, automated ladling system, or finished HPDC parts in production context. Note if this is a reference/industry image rather than Creative Alucast facility.

Process

How High Pressure Die Casting Works —
Step by Step

1

Cold Chamber Charging

Molten aluminium is ladled into the cold chamber shot sleeve from a holding furnace. The cold chamber is a separate cylinder — aluminium's high melting point (650°C+) makes hot chamber impossible.

2

High-Speed Injection

A hydraulic plunger drives the molten metal from the shot sleeve into the hardened steel die at 700–1,200 bar pressure. The die fills in milliseconds — too fast for air to escape, creating inherent gas porosity.

3

Intensification

After die fill, intensification pressure (up to 1,200+ bar) is applied to compact the solidifying metal, reducing shrinkage porosity while the part solidifies under extreme pressure.

4

Solidification

Metal solidifies in typically 5–30 seconds depending on section thickness. The hardened H13 die (held at 150–250°C) extracts heat rapidly, producing a fine-grained as-cast structure.

5

Ejection

Die opens and ejector pins push the casting out. Gate, flash, and biscuit are trimmed. Cycle time: 30–120 seconds total. Typical output: 200–500 shots per 8-hour shift.

6

Post-processing

Gate vestige removal, deburring, inspection, stress relief (TS, 200–250°C only — no T6), machining, and surface treatment. Impregnation for pressure-tight applications.

Materials

Aluminium Alloys Suitable for High Pressure Die Casting

Suitability ratings from BS 1490:1988 Table 8. Scale: 4 = Excellent, 3 = Good, 2 = Fair, n = Not normally recommended.
ALLOY NOMINAL COMPOSITION SUITABILITY NOTES
LM2 Al-Si10Cu2
4 - Excellent
Excellent — most widely used HPDC alloy globally. Best castability for HPDC.
LM20 Al-Si12
4 - Excellent
Excellent — eutectic alloy, best corrosion resistance of HPDC alloys.
LM24 Al-Si8Cu3.5
4 - Excellent
Excellent — highest tensile and best machinability of standard HPDC alloys.
LM6 Al-Si12
3 - Good
Good — LM20 preferred for HPDC, but LM6 castable.
LM25 Al-Si7Mg0.5
3n - Not normally recommended
Not normally recommended — T6 not applicable to HPDC. Use GDC/LPDC for LM25.
LM9 Al-Si12Mg0.5
n - Not recommended
Not recommended for HPDC per BS 1490 Table 8.
LM5 Al-Mg5Mn0.5
2 - Fair
Fair — oxide inclusions make LM5 difficult in HPDC.
LM30 Al-Si17Cu4.5
3 - Good
Good — only Group C alloy with positive HPDC rating. Hypereutectic piston alloy.

Heat Treatment on High Pressure Die Casting Castings

Standard HPDC castings cannot be T6 heat-treated — gas porosity causes blistering during solution treatment. Only stress relief (TS, 200–250°C) is applicable to conventional HPDC. Vacuum HPDC is an exception.

Tolerances

High Pressure Die Casting Dimensional Tolerances — ISO 8062-3:2007

Dimensional Casting Tolerance Grade per ISO 8062-3:2007. High Pressure Die Casting achieves DCTG 6–9. Tolerances are symmetrically disposed (±half the total band) unless individually specified.

NOMINAL DIMENSION TOLERANCE RANGE BEST (DCTG 6) WORST (9)
up to 10mm ±0.13-0.52mm ±0.13 ±0.52
10-25mm ±0.15-0.58mm ±0.15 ±0.58
25-100mm ±0.22-0.78mm ±0.22 ±0.78
100-250mm ±0.31-1.0mm ±0.31 ±1.0
250-400mm ±0.39-1.1mm ±0.39 ±1.1
Parting line Add 0.1-0.25mm — —
Wall thickness One DCTG grade coarser per ISO 8062-3 — —

Wall Thickness — One Grade Coarser per ISO 8062-3

Per ISO 8062-3:2007 Clause 7: wall thickness tolerances are one DCTG grade coarser than the general stated DCTG. Account for this when specifying wall thickness tolerances on engineering drawings.

Surface Finish

Per ISO 8062-3:2007 Clause 7: wall thickness tolerances are one DCTG grade coarser than the general stated DCTG. Account for this when specifying wall thickness tolerances on engineering drawings.

Machining Allowances (RMA) — ISO 8062-3 Annex B

SURFACE TYPE REQUIRED MACHINING ALLOWANCE
Small surfaces (≤100mm) 0.5-1.0mm per face (RMAG A-B)
Medium surfaces (100 0.75-1.5mm per face (RMAG B-C)
Large surfaces (>300mm) 1.0-2.0mm per face (RMAG C)
Bores and holes 0.5-1.5mm on radius

Design Guide

High Pressure Die Casting Design Rules — Wall Thickness, Draft & Tooling

Minimum Wall Thickness

Section / Condition Minimum Thickness
Minimum wall thickness(≤100mm) 1.0–2.0mm — thinnest of all casting processes(≤100mm)
Recommended production wall 2.0–4.0mm for consistent fill and mechanical properties (≤100mm)
Maximum practical wall (>300mm) 12–15mm — porosity increases significantly with section thickness (>300mm)
Rib thickness 0.5–0.8× adjoining wall thickness(>300mm)
Boss wall thickness ≤2× boss diameter; boss wall = 0.6× boss diameter(>300mm)

Draft AngleS

Draft is applied to all surfaces parallel to the die opening direction. Measured from the direction of draw.
Surface Feature Required Draft
External surfaces (short draw ≤25mm)(≤100mm) 0.5° min — finest draft of all processes(≤100mm)
External surfaces (medium draw 25–100mm) 0.5°–1° (≤100mm)
External surfaces (long draw >100mm)(>300mm) 1°(>300mm)
Internal surfaces (metal cores/slides) 1°–2°(>300mm)
Textured surfaces Add 1°–3° to base draft(>300mm)

Draft Calculation

At 1° draft over 100mm depth, the face offset is 100 × tan(1°) = 1.75mm. Calculate the resulting dimensional variation for all draft surfaces before finalising the design, especially on functional dimensions.

ToolinG

Parameter Details
Die material H13 tool steel — hardened to 44–48 HRC, nitride coated for die soldering resistance
Machine type Cold chamber — aluminium requires cold chamber; hot chamber only for zinc/magnesium
Tooling lead time 8–16 weeks for complex tooling with slides and core pulls
Die life 100,000–500,000 shots depending on alloy temperature and die cooling design
Tooling cost Highest of all casting processes — typically 3–5× GDC tooling cost
Slides & cores Metal side-actions and core pulls allow undercuts — adds significant cost

Evaluation

Advantages & Limitations of High Pressure Die Casting

Advantages

  • Thinnest walls achievable: 1.0–2.0mm — impossible in sand or gravity die casting
  • Finest as-cast surface finish: Ra 0.8–3.2 µm — near machined quality
  • Fastest cycle time: 30–120 seconds — highest production rates
  • Lowest per-piece cost at high volumes (>10,000 pieces/year)
  • Minimal machining stock (0.5–1.5mm per face)
  • Consistent shot-to-shot quality in automated production
  • Complex external geometry achievable with slides and core pulls

Limitations

  • NOT normally heat-treatable to T6 — gas porosity causes blistering during solution treatment
  • Highest inherent porosity of all casting processes
  • Alloy choice restricted: primarily LM2, LM20, LM24
  • Highest tooling cost (3–5× GDC tooling)
  • Longest tooling lead time (8–16 weeks)
  • Ejector pin marks and gate vestige on all HPDC castings
  • Not suitable for structural safety-critical parts (unless Vacuum HPDC)
  • Economical only at high volumes (typically >10,000 pieces/year)
  • Maximum wall thickness ~15mm practical limit

Applications

Typical Applications — High Pressure Die Casting

HPDC Applications — Automotive & Electronics

Array of representative HPDC aluminium castings — thin-wall automotive housings, electronic enclosures, connector bodies. Shows the design freedom and surface quality achievable at high volumes.
Industry Typical Parts Why High Pressure Die Casting
Automotive Engine housings, transmission brackets, air intake manifolds, alternator housings, oil pump bodies Thin-wall, high-volume, dimensional precision at automotive scale
Electronics Laptop housings, 5G base station frames, heat spreaders, camera housings Thin wall 1–2mm, fine surface finish, EMI shielding
Consumer Products Door handles, window hardware, appliance components, power tool housings High-volume economy, good surface for painting/plating
Telecommunications Antenna housings, radio frames, connector bodies Complex geometry, thin wall, tight tolerances
Electrical Motor frames, connector housings, junction boxes, LED heat sinks Volume production, consistent dimensions, thermal conductivity
Industrial High-volume instrument housings, brackets, covers Lowest per-piece cost at production volumes

Frequently Asked Questions

Common Questions About High Pressure Die Casting

What is High Pressure Die Casting (HPDC)?
HPDC is a casting process where molten aluminium is injected into a hardened steel die at 700–1,200 bar pressure in milliseconds. It produces the thinnest walls (1–2mm), finest surface finish (Ra 0.8–3.2 µm), and tightest tolerances (DCTG 6–9) of any casting process. It is the dominant process for high-volume automotive and consumer product casting.
The high-velocity turbulent fill of HPDC traps air and gases as micro-porosity throughout the casting. During solution treatment at 515–525°C, these entrapped gases expand, causing the casting surface to blister. Standard HPDC castings can only be stress relieved (TS, 200–250°C). Vacuum HPDC removes most entrapped gas and allows T6 heat treatment.
The primary HPDC alloys are LM2 (Al-Si10Cu2, most widely used globally), LM24 (Al-Si8Cu3.5, best tensile and machinability), and LM20 (Al-Si12, best corrosion resistance). All are rated 4 (Excellent) for HPDC per BS 1490 Table 8. LM25 is not normally recommended for HPDC.
HPDC can achieve 1.0–2.0mm minimum wall thickness — the thinnest of any casting process. Recommended production wall thickness is 2.0–4.0mm for consistent fill and mechanical properties. Maximum practical wall thickness is 12–15mm, as porosity increases significantly with section thickness.
HPDC achieves DCTG 6–9 per ISO 8062-3:2007 — the tightest of all casting processes. Typical linear tolerances are ±0.22–0.78mm for 25–100mm dimensions, and ±0.39–1.1mm for 250–400mm dimensions. Across the parting line add 0.1–0.25mm.
MoS₂ (molybdenum disulfide) is a dry film lubricant coating per MIL-PRF-46010. Its lamellar crystal structure allows layers to shear at very low force, giving friction coefficients as low as 0.03–0.05 in dry/vacuum conditions. Specify it for sliding or rotating assemblies where liquid lubricants cannot be replenished, for anti-galling on precision threaded assemblies, and for components in vacuum, cryogenic, or food-contact environments. Performance degrades in wet conditions — avoid for wet sliding applications.
Specify HPDC when: (1) wall thickness below 3mm is required; (2) annual volume exceeds 10,000+ pieces; (3) surface finish Ra <3.2 µm as-cast is required; (4) T6 heat treatment is not required. Specify GDC or LPDC when T6 is needed, when volume is below 5,000 pieces/year, or when safety-critical structural integrity is required.
Ejector pins are required to push the casting out of the die — they leave circular marks on the casting surface. The gate (where metal enters the die) leaves a vestige after trimming. Both are inherent to HPDC and must be accounted for in the design — ejector pin locations and gate position should be agreed between customer and foundry before die design begins.

Casting Processes

SAND CASTING

SAND CASTING

TILT GDC

TILT GDC

LPDC

LPDC

HPDC

HPDC
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