Ano ang Cast Aluminum? Mga Katangian, Mga Proseso & Mga Aplikasyon

Talahanayan Ng Nilalaman Ipakita ang

1. Panimula

Cast aluminum is a versatile material created by pouring molten aluminum alloy into a mold and allowing it to solidify.

Widely used across industries, it offers a blend of lightweight properties, magandang lakas, at paglaban sa kaagnasan.

From automotive engines to aerospace components, cast aluminum plays a crucial role in modern manufacturing.

2. Ano ang Cast Aluminum?

Cast aluminum refers to parts produced by pouring molten aluminum into a mold cavity, allowing the metal to solidify and then extracting a near‑net‑shape component.

Hindi tulad ng ginawa aluminyo, which forms through rolling, paglabas ng mga, o pagkukubli, casting unlocks complex geometries, integrated ribs, and internal cavities in a single pour.

Core Terminology

Termino	Kahulugan
Pattern	A positive replica of the part—made from wood, plastik na plastik, or metal—used to form the mold cavity.
Amag	The negative cavity (buhangin, metal, or ceramic) that shapes the casting.
Gating System	Network of sprue, Mga Runner, and gates that transports molten aluminum from the pouring basin to the mold.
Riser (Tagapagpakain)	Reservoir of liquid metal connected to the cavity; it supplies molten metal during solidification shrinkage.
Allowance sa Pag-urong	Extra material (usually 1–2 %) added to the pattern dimensions to compensate for metal contraction.
Core	A sand or ceramic insert placed inside the mold to create internal cavities or undercuts in the casting.

3. Key Aluminum Casting Processes

Aluminum’s versatility shines through the variety of casting methods available. Each process suits different part geometries, production volumes, and property requirements.

Sand Casting Aluminum

Buhangin paghahagis is one of the most versatile casting processes.

Ipasadya ang Paghahagis ng Buhangin ng Malaking Mga Bahagi ng Engineering Aluminum

It is well-suited for producing large or complex shapes, such as engine blocks for heavy machinery or custom architectural components.

The process is relatively inexpensive for low to medium production runs since the sand molds can be easily created and modified.

Gayunpaman, it typically results in a rougher surface finish and less precise dimensions compared to other methods.

Die Casting Aluminum

Die casting is the go-to process for high-volume production of parts with tight tolerances. It involves injecting molten aluminum under high pressure into a metal die.

This allows for rapid production cycles, often as short as a few seconds per part.

Die-cast parts have excellent surface finishes and can achieve very precise dimensions, making them ideal for automotive components like transmission cases, Mga Mount ng Makina, and decorative trim.

Investment Casting Aluminum

Pamumuhunan sa paghahagis, also known as the lost-wax process, excels in creating parts with intricate details and high surface quality.

It is commonly used in the aerospace industry for manufacturing turbine blades, in the jewelry industry for detailed designs, and in medical device manufacturing for components with complex geometries.

The process enables the production of parts with extremely fine features and tight tolerances.

Customized Investment Casting Aluminum Cast Part

Permanent-Mold Casting Aluminum

Permanent-mold casting offers better control over the microstructure of the cast part.

Since the metal mold can be preheated and cooled precisely, it results in more consistent mechanical properties and reduced porosity.

This method is suitable for producing parts with relatively simple geometries in medium to high volumes, such as certain types of automotive pistons and pump housings.

Emerging and Hybrid Methods

Vacuum Casting: By performing the casting process in a vacuum environment, it reduces the presence of gases in the molten metal, minimizing porosity and improving the quality of the casting.
Pisil Casting: Applies external pressure during the solidification process, enhancing the density and strength of the casting.
This method is useful for producing parts that require high mechanical performance.
Semi-Solid Casting: Involves casting a partially solidified aluminum alloy, which offers unique advantages in terms of formability and the ability to produce parts with enhanced mechanical properties.

Proseso	Dami	Pagpaparaya	Mga kalakasan	Mga Limitasyon
buhangin paghahagis	Mababa - Katamtaman	± 0.5–1.5%	Large parts (up to 50 t), low tooling cost	Rough finish (Ra 6–12 μm), slower cycle
mamatay paghahagis	Mataas na	± 0.1–0.3%	Fast cycles, masikip na mga tolerance, makinis na tapusin (Ra 1–3 µm)	High die cost ($10 k–$100 k)
Pamumuhunan sa Paghahagis	Mababa - Katamtaman	± 0.1–0.3%	Complex geometry, fine detail (Ra ≤ 1 µm)	Expensive tooling, slower throughput
Permanent‑Mold Casting	Katamtaman	± 0.2–0.5%	Controlled microstructure, magandang lakas	Mold wear limits complexity
Semisolid/Squeeze/Vacuum	Umuusbong na	± 0.1–0.3%	Nabawasan ang porosity, high integrity	Specialized equipment

4. Alloy Selection of Cast Aluminum

Choosing the right aluminyo haluang metal for casting hinges on balancing mekanikal na lakas, paglaban sa kaagnasan, pagkatubig, at thermal properties.

Cast Aluminum Blocks for Automotive Engines

Silicon‑Rich Alloys (3xx.x Series)

These alloys offer excellent fluidity, mababang pag-urong, and good corrosion resistance—ideal for die and sand casting.

haluang metal	Pangunahing Komposisyon	Lakas ng Paghatak	Typical Uses
A380	8–12% Si, 3–4% Cu	180–240 MPa	Die‑cast housings, small intricate parts
A383	9–12% Si, 1–2% Cu	190–240 MPa	Die‑cast valve bodies, Mga pabahay ng pump
A413	10–13% Si, 0.8–1.5% Cu	210–260 MPa	High‑pressure die‑cast gearbox cases
A360	7–11% Si, <1% Mg	150–220 MPa	Thin‑wall die‑cast components

Copper‑Bearing Alloys (4xx.x Series)

Copper strengthens the alloy and improves machinability, at some cost to corrosion resistance.

haluang metal	Pangunahing Komposisyon	Lakas ng Paghatak	Typical Uses
A319	3–5% Cu, 5–7% Si	240–280 MPa	Engine cylinder heads, mga kaso ng transmisyon
A356-T6	7% Si Si, 0.3% Mg	260–320 MPa	Mga gulong ng sasakyan, Mga pabahay ng pump
A357-T6	7% Si Si, 0.5% Mg	280–330 MPa	High‑stress automotive parts
A354	3–5% Cu, 8–12% Si	220–270 MPa	General die‑castings requiring strength

Magnesium‑Alloyed Casts (5xx.x Series)

Magnesium provides solid‑solution strengthening and excellent corrosion resistance in marine environments.

haluang metal	Pangunahing Komposisyon	Lakas ng Paghatak	Typical Uses
A535	5–6% Mg, 0.3% Mn	290–340 MPa	Hardware ng dagat, presyon vessels
A356.2‑T6	7% Si Si, 0.3% Mg	260–320 MPa	Aerospace castings, structural brackets

Specialty and High‑Performance Alloys

These alloys push the envelope for strength, thermal katatagan, or precision.

haluang metal	Pangunahing Komposisyon	Lakas ng Paghatak	Typical Uses
A206‑T7	6% Cu, 4% Ni, 0.5% V	300–350 MPa	Aerospace forging replacements
A390	17–21% Si, 3–4% Cu	260–300 MPa	Mga bahagi ng preno, wear‑resistant castings
ADC12 (Hapon)	10–13% Si, 2–4% Cu	200–260 MPa	Japanese die‑cast electronics enclosures

5. Physical and Mechanical Properties of Cast Aluminum

Cast aluminum offers a compelling blend of lightweight structure, good thermal characteristics,

and moderate-to-high mechanical strength, making it ideal for a wide array of industrial, automotive, at mga bahagi ng aerospace.

Gayunpaman, its properties vary significantly depending on alloy composition, casting method, and post-casting treatment.

Cast Aluminum Led Heat Sink — Cast Aluminum LED Heat Sink

Physical Properties of Cast Aluminum

Pag-aari	Tipikal na Halaga (Saklaw)	Mga Tala
Densidad ng katawan	2.63–2.80 g/cm³	~1/3 the density of steel
Punto ng Pagtunaw	565–770 °C	Varies by alloying elements (Si Si, Cu, Mg)
Thermal kondaktibiti	80–170 W/m·K	High in pure aluminum, lower with added alloying elements
Koepisyent ng Thermal Expansion	21–25 × 10⁻⁶ /K	Important in joint design (expansion mismatch)
Electrical kondaktibiti	20–45% IACS	Much lower than pure aluminum due to alloying

Mechanical Properties of Cast Aluminum

Mechanical performance varies with alloy, casting method, at paggamot sa init. The table below outlines the typical tensile, ani, and fatigue properties of selected alloys.

haluang metal	Proseso	Lakas ng Paghatak (MPa)	Yield Lakas (MPa)	Pagpapahaba (%)	Limitasyon ng Pagkapagod (MPa)
A356 (bilang cast)	Buhangin paghahagis	180–220	120–160	3–5	~ 50
A356-T6	Buhangin paghahagis + Init na ginagamot	250–310	170–230	5–10	90–110
A319	Die casting	210–260	140–180	2–4	~60
A380	Die casting	180–240	120–170	1–3	~ 50
A206-T7	Permanent mold	320–370	250–300	3–5	100+

Katigasan at Paglaban sa Pagsusuot

Hardness is typically measured using the Brinell Hardness Number (BHN).

haluang metal	Ang katigasan ng ulo (BHN)	Magsuot ng Paglaban
A356 (bilang cast)	65–75	Katamtaman
A356-T6	80–90	Mabuti na lang
A390	100–120	Napakahusay (high Si content)
A206-T7	100–110	Mabuti na lang

6. Advantages and Limitations of Cast Aluminum

Cast aluminum has become a cornerstone material in modern manufacturing due to its unique combination of lightweight characteristics, pagiging formable, at lakas.

Advantages of Cast Aluminum

Complex Geometries with Minimal Machining

Casting allows for the creation of intricate shapes—including internal cavities, fins, and ribs—that would be costly or impossible to produce using subtractive methods.

This significantly reduces machining time and material waste.

Lightweight and High Strength-to-Weight Ratio

With a density of ~2.7 g/cm³, cast aluminum components can reduce structural weight by up to 60% compared to cast iron,

while maintaining respectable strength (hal., A356-T6: 260–310 MPa tensile strength).

Cost Efficiency at Medium-to-High Volumes

Processes like high-pressure die casting (HPDC) and permanent mold casting offer low per-part costs when scaled. Die life in HPDC can exceed 100,000 cycles with proper maintenance.

Excellent Thermal and Electrical Conductivity

Ideal for components like heat sinks, mga pabahay, and electric motor parts—thermal conductivity ranges from 90–170 W/m·K depending on alloy.

Paglaban sa kaagnasan

Aluminum naturally forms a protective oxide layer. Alloys with silicon and magnesium (hal., A356) show good corrosion resistance even in marine environments.

Compatibility with Post-Processing

Cast aluminum accepts a wide range of surface treatments and coatings (pag anod ng, patong ng pulbos) and can be heat treated (T5, T6) upang madagdagan ang lakas at katigasan.

Limitations of Cast Aluminum

Porosity and Shrinkage Defects

Gas entrapment, hydrogen solubility, and solidification shrinkage often cause microporosity—reducing mechanical strength and sealing capability.

Even with degassing and mold design optimizations, some porosity is inherent to casting.

Lower Ductility Compared to Wrought Alloys

Cast structures exhibit coarse dendritic grains and limited elongation (Karaniwan <10%). Halimbawa na lang, A356-T6 has elongation of ~5–9%, while wrought 6061-T6 reaches ~12–17%.

Dimensional Tolerance Challenges

Compared to machined or forged parts, cast aluminum components may have wider dimensional tolerances due to mold wear, pagpapalawak ng thermal, and mold fill variations—especially in sand casting.

Wall Thickness and Flow Limitations

Die-cast aluminum typically requires a minimum wall thickness of 1.5–2.5 mm to ensure full mold fill and structural integrity.

Thin walls in complex parts may cause incomplete filling or cold shuts.

Limited Fatigue and Impact Resistance

Surface defects, pores, and coarse grain structures reduce fatigue life. Cast aluminum fatigue strength is generally 25–40% lower than forged or wrought equivalents.

Alloy Restrictions by Process

Not all aluminum alloys are suitable for every casting method.

Halimbawa na lang, 7075 at 2024 high-strength wrought alloys cannot be die cast due to their poor fluidity and hot-cracking tendency.

7. Surface Finishes and Post‑Casting Treatments

Mga Paggamot sa Init

T5 Aging: Involves artificial aging after air cooling from the casting temperature.
This process improves the strength and hardness of the casting by promoting the precipitation of alloying elements.
T6 Aging: Consists of solution heat treatment (heating the casting to a specific temperature and holding it for a period), followed by quenching (mabilis na paglamig) and artificial aging.
T6 aging results in even higher strength and hardness compared to T5 aging.

Paglilinis ng Ibabaw

Pagsabog ng Shot: Uses small pellets (such as steel shot or glass beads) propelled at high speed to blast the surface of the casting.
This process removes scale, kalawang, at iba pang mga contaminants, and can also improve the surface roughness for better adhesion of coatings.
Chemical Etch: Involves immersing the casting in a chemical solution that etches away the surface layer, removing oxidation and other impurities.
De-oxidation: Specific treatments to remove the natural oxide layer on the aluminum surface, preparing it for further processing or coating.

Coatings and Machining

Pagpapahid ng langis: Creates a protective oxide layer on the surface of the aluminum, enhancing corrosion resistance and providing an aesthetic finish.
The thickness of the anodized layer can vary depending on the application.
Palabok na patong: Applies a dry powder coating to the surface, which is then cured under heat to form a durable, proteksyon, and decorative finish.
Pagpipinta: Can be used to provide both protection and a custom color or appearance.
Machining: Operations such as milling, pagliko, and drilling are performed to achieve tight tolerances and the desired surface finish,
especially for parts with critical dimensions or functional surfaces.

8. Mga Application ng Cast Aluminum

Cast aluminum plays a pivotal role across a wide range of industries, thanks to its lightweight, paglaban sa kaagnasan, good thermal properties, and ability to be formed into complex shapes.

Industriya ng Automotive

The automotive sector is the largest consumer of cast aluminum globally.

As manufacturers strive to reduce vehicle weight for better fuel efficiency and lower emissions, aluminum casting is the go-to material for numerous critical components.