Aluminium Casting · Creative Alucast
Low Pressure
Die Casting
The die fills from below — metal rises through a riser tube under controlled gas pressure, calmly and turbulence-free. The result is a dense, low-porosity casting with mechanical properties that gravity alone cannot match.
CT5–CT7 Tolerance
Ra 1.6–3.2 µm
0.5–30 kg
0.02–0.1 MPa Fill Pressure
T5/T6 Heat Treatable
CT5-7
Dimensional tolerance
Ra 1.6
Surface finish (µm)
30 kg
Max casting weight
0.1 bar
Max fill pressure (MPa)
LM25
Primary alloy grade
The LPDC Principle
Metal Rises.
Pressure Feeds.
Gravity Doesn't.
Process Overview
Fill from Below.
Feed from Below.
Fewer Defects.
In conventional gravity casting — sand or die — metal falls into the cavity from above. What it carries with it is the problem: turbulence, oxide skins, entrained gas, and a solidification sequence that begins at the top, where the metal first cools, rather than from the bottom up where pressure-feeding can compensate for shrinkage.
Low pressure die casting inverts this. The die sits above a sealed furnace. Controlled gas pressure — 0.02 to 0.1 MPa — pushes molten metal up through a ceramic riser tube into the die from below. Metal enters calmly. It fills from the bottom. Solidification progresses upward toward the gate, which remains liquid under sustained pressure — feeding shrinkage continuously as the casting solidifies.
The result is a casting with significantly lower porosity, better mechanical properties, and superior dimensional repeatability than any gravity-poured equivalent — consistently, across every shot.
Gravity Die / Sand
Metal falls in from the top — turbulence, shrinkage porosity, limited
feeding capacity
LPDC
Metal rises from below under controlled pressure — laminar fill, continuous feeding, dense solidification
How It Works
Six Steps to a Pressure-Dense Casting
The LPDC process sequence — from furnace preparation through pressurised fill, directional solidification, pressure release, and part extraction.
Step 01
Die Preparation & Pre-Heat
The permanent die is cleaned, coated with release agent, and pre-heated to 200–300°C. The holding furnace is charged with verified alloy and brought to casting temperature (700–740°C for LM25).
Step 02
Core Setting & Die Close
Where internal passages are required, cores are set in position. The die halves close and clamp. The die sits directly above the sealed holding furnace with the riser tube connecting both.
Step 03
Controlled Pressure Fill
Gas pressure (0.02–0.1 MPa) is applied to the furnace. Metal rises smoothly up the riser tube and into the die cavity from below. Fill rate is precisely controlled by ramp profile slow, laminar, turbulence-free.
Step 04
Pressure-Fed Solidification
Once the die is full, pressure is held at a higher level. The casting solidifies from the top downward toward the still liquid riser. Shrinkage is continuously compensated by fresh metal fed up from the furnace under pressure eliminating shrinkage porosity.
Step 05
Pressure Release
Once solidification is complete, furnace pressure is released. Any remaining liquid metal in the riser tube falls back into the furnace — leaving a clean gate. The riser tube is not waste metal.
Step 06
Extraction & Fettling
The die opens, the casting is extracted by ejector pins, and any gates, runners, and overflows are removed. Cores are cleaned out. The casting is shot-blasted and passes to inspection or heat treatment.
Process Specifications
LPDC
Capability Data
| Weight Range | 0.5 kg – 30 kg |
| Dimensional Tolerance | CT5–CT7 (ISO 8062) |
| As-Cast Surface Finish | Ra 1.6–3.2 µm |
| Die Material | H13 / H11 tool steel |
| Fill Pressure | 0.02–0.1 MPa (0.2–1 bar) |
| Pouring Temperature | 700–740 °C (LM25) |
| Die Pre-Heat Temperature | 200–300 °C |
| Core Options | Sand core · Dissolving-core |
| Heat Treatment | T4, T5, T6, T7 (alloy dependent) |
| Production Volume | Medium (500–50,000 ppa) |
Surface Finish Options
Complete
Part Supply
Heat Treatment (T5 / T6)
Full T6 cycle for LM25 — solution treatment, quench, and artificial ageing to achieve 260–300 MPa UTS.
CNC Machining
Turning, milling, boring, drilling, and tapping — complete machined and dimensioned component supply.
Pressure Testing
Hydraulic and pneumatic pressure test for pump bodies, manifolds, and pressure-rated housings.
Surface Coating
Hard anodise, powder coating, Alodine, or MoS₂ — applied after machining to drawing specification.
CMM & Spectrometric Inspection
Dimensional CMM report, alloy heat verification, and mechanical property certification supplied with batch.
Alloy Suitability
Best Alloys for LPDC
LM25 dominates LPDC production for structural applications. Its combination of fluidity, low shrinkage, and response to T6 heat treatment makes it the first choice for pressure-critical and safety-rated castings.
LM25
Al-Si7Mg · EN AC-42100
The benchmark LPDC structural alloy. T6 heat treatment achieves 260–300 MPa UTS. Excellent pressure tightness, low shrinkage, outstanding fatigue resistance.
- Primary
LM6
Al-Si12 · EN AC-44100
Eutectic alloy — excellent fluidity for thin-section and complex geometry LPDC. Outstanding corrosion resistance. Not heat treatable but reliable in marine and chemical environments.
LM16
Al-Si5Cu1Mg · EN AC-43200
Higher elongation and impact resistance than LM25. T5 heat treatable. Specified where ductility and toughness are as important as ultimate strength.
LM9
Al-Si12Mg · EN AC-44200
Combines LM6 fluidity with heat treatability. Marine environments requiring corrosion resistance alongside improved strength beyond the standard eutectic grade.
LM4
Al-Si5Cu3 · EN AC-45000
General-purpose moderate-strength alloy. Good machinability, reasonable pressure tightness. Suitable for LPDC production of medium-duty components.
Alloy Selection
Tell Us Your Application
Service environment, required strength, corrosion requirements — we’ll confirm the right alloy and heat treatment route.
Process Advantages
Why Specify LPDC
Six reasons LPDC delivers better aluminium castings than gravity die or sand casting — particularly for pressure-critical, structural, and high-integrity applications.
Pressure-Fed Solidification
Sustained pressure during solidification feeds shrinkage continuously from below — eliminating the shrinkage porosity that gravity casting cannot prevent. Denser, stronger castings as a direct result.
Tighter Tolerances
Controlled fill and consistent process parameters deliver CT5–CT7 dimensional accuracy — tighter than tilt GDC and significantly better than sand casting — reducing machining allowances needed.
Turbulence-Free Fill
Metal rises from below under controlled pressure — no splashing, no oxide entrapment, no gas porosity from turbulent fill. The cleanest possible melt delivery into the die cavity.
High Pressure Tightness
The combination of turbulence-free fill and pressure-fed solidification produces castings inherently resistant to through-porosity — suitable for hydraulic, pneumatic, and pressure-rated applications.
Excellent Metal Yield
Unfilled riser metal drains back to the furnace at pressure release — not scrapped. Metal yield is significantly higher than sand casting where risers and runners are scrapped with each casting.
Superior Surface Finish
Permanent die cavity and controlled low-turbulence fill produce Ra 1.6–3.2 µm as-cast — among the best achievable in aluminium gravity casting — minimising post-cast machining on non-functional faces.
Applications
Where LPDC Is Specified
LPDC is the process of choice when pressure tightness, structural integrity, and tight dimensional tolerance must be guaranteed consistently — typically for components that carry load, contain pressure, or must not leak.
Automotive
Wheel Hubs & Brake Calipers
Safety-critical structural castings where porosity is not permissible — wheel hubs, steering knuckles, and brake calipers are primary LPDC applications in automotive.
Pump & Valves
Pump Casings & Manifolds
Pressure-tight pump bodies, impeller housings, and valve manifolds requiring hydraulic integrity — LPDC’s low-porosity structure eliminates through-porosity leakage paths.
Power & Energy
Generator Frames & Motor Housings
Structural castings for generator end-shields, motor frames, and power distribution housings — where T6-treated LM25 meets the strength and dimensional requirements.
Fire Equipment
Pressure-Rated Valve Bodies
Fire suppression valve bodies and pressure system components requiring certification under hydraulic test — LPDC porosity levels are suited to these applications.
Electrical
Switchgear & Enclosure Structures
Electrical enclosure frames, junction box bodies, and busbar housings where dimensional accuracy, anodisability, and structural integrity are specified together.
Medical
Precision Device Housings
Medical equipment structural housings and bracket castings where tight tolerances, anodisable surface, and clean metallurgy are required for regulatory compliance.
Process Comparison
LPDC vs Other
Casting Routes
How LPDC compares to sand casting, tilt GDC, and HPDC across the properties that matter most to engineers specifying a casting process.
| Process | Tolerance | Surface Finish | Porosity | Pressure Tight | Weight Range | Heat Treatable |
|---|---|---|---|---|---|---|
| Sand Casting | CT8–CT10 | Ra 6.3–25 µm | Moderate | Conditional | 0.1–500 kg | Yes |
| Tilt GDC | CT6–CT8 | Ra 3.2–6.3 µm | Low | Good | 0.05–50 kg | Yes |
| LPDC ◆ | CT5–CT7 | Ra 1.6–3.2 µm | Very Low | Excellent | 0.5–30 kg | Yes |
| HPDC | CT4–CT6 | Ra 0.8–1.6 µm | Low (gas) | Good (thin wall) | 0.01–25 kg | Limited |
Advanced LPDC Capability
LPDC + Dissolving-Core:
The Most Demanding
Geometries. Solved.
LPDC already produces the lowest-porosity, highest-integrity gravity casting available. But there is a class of geometry it cannot address with conventional cores: blind undercuts, crossing internal channels, and fully enclosed hollow structures where no sand or metal core can be extracted after solidification.
Dissolving-core casting is fully compatible with the LPDC process. The expendable core is placed in the die before the pressure fill cycle. Metal rises around it under controlled pressure — producing a dense, low-porosity casting with the internal geometry locked inside. The core is then removed cleanly by water dissolution. Zero residue. Zero mechanical stress.
The combination of LPDC’s density and feeding efficiency with dissolving-core geometry freedom produces castings that were simply not achievable by any conventional route.
- Blind undercuts and enclosed hollows — cast in a single LPDC shot
- LPDC pressure feeding maintained throughout — no compromise to density
- Core dissolves completely in water after casting — zero residue
- One-piece castings replacing multi-part welded or bolted assemblies
- Compatible with LM25 T6 — full structural properties maintained
Pump & Hydraulic
Multi-Directional Internal Passages — One Casting
Pump bodies and hydraulic manifolds with crossing or blind internal bores — where no slider or sand core can be reliably extracted — produced as one complete LPDC casting with full pressure integrity.
Automotive & EV
Structural Hollow Components with Integrated Cooling
Hollow one-piece LM25 LPDC castings with internal cooling channels or oil passages — combining the density and strength of LPDC with internal geometry that sliders cannot reach.
Assembly Consolidation
Multiple Parts Consolidated into One LPDC Casting
Assemblies currently bolted, welded, or sealed from multiple pieces to create an internal cavity — redesigned as a single LPDC dissolving-core casting. No joints. No sealing risk. Lower total cost.
The Question Worth Asking
Can Your Assembly Become a Single LPDC Casting?
If your component has internal geometry that cannot be extracted by conventional means — bring it to us. We’ll tell you whether dissolving-core LPDC can solve it.
FAQ
LPDC Question
Common engineering questions about the LPDC process, its advantages over other casting routes, alloy suitability, and geometry capability.
What is low pressure die casting?
Low pressure die casting fills the die from below by applying controlled gas pressure (0.02–0.1 MPa) to molten metal in a sealed furnace below the die. Metal rises through a ceramic riser tube, filling the die calmly from the bottom. No turbulence. Sustained pressure during solidification feeds shrinkage, producing dense, low-porosity castings with superior mechanical properties.
How does LPDC compare to gravity die casting?
In gravity die casting, metal falls into the die under gravity — creating turbulence and potential for oxide and gas entrapment. In LPDC, metal rises from below under controlled pressure — no turbulence, better shrinkage feeding, higher density, and improved mechanical properties. LPDC achieves CT5–CT7 tolerance vs CT6–CT8 for tilt GDC, and Ra 1.6–3.2 µm vs Ra 3.2–6.3 µm in the as-cast condition.
Can LPDC produce complex internal geometries?
Conventional LPDC can incorporate sand cores for internal passages. For more complex geometries — blind undercuts, crossing internal channels, or hollow structures that no conventional core can produce and extract — Creative Alucast’s dissolving-core casting is compatible with the LPDC process, enabling one-piece hollow castings previously impossible by conventional means, while maintaining LPDC’s density and pressure integrity.
What alloys are recommended for LPDC?
LM25 (Al-Si7Mg) is the preferred LPDC alloy — T6 heat treatment achieves 260–300 MPa UTS. LM6 is used for marine and corrosion-resistant parts. LM16 is specified where better elongation and impact resistance are needed. All are routinely cast by LPDC at Creative Alucast.
Is LPDC suitable for pressure-tight components?
Yes — LPDC is specifically suited to pressure-tight applications. The combination of turbulence-free fill and sustained pressure feeding during solidification eliminates the shrinkage porosity and oxide inclusions that cause leakage in gravity-cast components. LPDC castings are routinely pressure-tested for pump bodies, valve housings, and hydraulic components at Creative Alucast.
Start Your
LPDC Project
Send us your drawing — we’ll review alloy selection, tool design, and process suitability, and provide a complete casting-to-finish quotation. Complex internal geometry? Ask about dissolving-core LPDC.