Cast Aluminum vs Cast Iron: Which Material Is Suitable?
Cast Aluminum vs Cast Iron
Cast aluminum and cast iron are widely used metals, but in distinct applications. The cast aluminum vs cast iron comparison is crucial because the two present different properties, such as corrosion resistance, weight, thermal conductivity, and strength.
Cast aluminum contains mostly aluminum, with small proportions of magnesium, manganese, copper, iron, and other elements. Cast aluminum is light, corrosion-resistant, and strong (when alloyed with other elements).
Cast iron is made by melting and molding iron, resulting in a material with a variety of properties based on specific composition and further treatment. Notable variants of cast iron are gray cast iron, white cast iron, malleable cast iron, and ductile cast iron.
This article focuses on the differences between cast iron and cast aluminum.
What Is Cast Aluminum?
Cast aluminum is an aluminum part made by pouring molten aluminum into a mold with the desired shape. First, the aluminum alloy is heated to its melting point to make it ready for pouring into the mold.
Aluminum casting process
Not every aluminum alloy can be cast. A material qualifies for casting if it has low shrinkage, high fluidity, good machinability, and hot cracking resistance. Popular aluminum grades for casting are
There are three types of aluminum casting: Sand casting, die casting, and permanent mold casting.
Sand Casting
Sand casting entails the use of a sand mixture mold with the requisite cores inside to make parts of varying complexity. Molten aluminum is poured through runners and left to cool and solidify. The sand mold is then demolished, and the complete part is retrieved.
Die Casting
While gravity is solely at play in sand casting, die casting introduces pressure to push molten aluminum into the mold cavity. The manufacturer may use die casting instead of sand casting to achieve higher dimensional accuracy, a smoother surface finish, or increase the manufacturing effectiveness.
A die-cast aluminum part
Permanent Mold Casting
Permanent mold casting uses reusable or permanent molds made of a material with a higher melting point to create cast aluminum parts. The molten aluminum is poured into the mold as usual, left to cool and solidify, and then removed. The mold is opened, and the part is taken for further processing if necessary.
What Is Cast Iron?
Cast iron is a product made by heating iron ore in a furnace, pouring the molten metal to form an ingot. The final shape is produced by remelting the ingot.
Cast iron ingots
Most people mistakenly think that cast iron contains 100% iron, while in fact, the primary iron alloy should have at least 2% carbon.
There are also other small proportions of silicon, manganese, and other alloys, which are added to enhance the cast iron properties. The main types of cast iron are gray cast iron, malleable cast iron, malleable iron, and white cast iron.
What Are The Benefits Of Cast Aluminum?
Cast aluminum presents unique benefits in projects, including the following;
- It is corrosion-resistant
- Low-weight material
- Has high thermal conductivity
- It is non-toxic
- It is a recyclable material
- It is non-magnetic
What Are The Limitations/Disadvantages Of Cast Aluminum?
The material also has some limitations, which are important to note for project success.
- It has relatively low tensile strength
- The cast material can be very porous
- Highly prone to physical damage
- Can be expensive
What Are The Advantages Of Cast Iron?
The same case applies to cast iron; the material has some advantages that appeal to manufacturers in construction, transportation, and other related applications.
- Outstanding compressive strength
- Durable
- Superior acoustic insulation
- Easy to machine
- Low-cost material
What Are The Limitations Of Cast Iron?
The shortcomings of cast iron are;
- Brittleness
- Prone to rusting
- Relatively heavier compared to cast aluminum
Which Is Better, Cast Aluminum Or Cast Iron?
When considering the better option between cast aluminum vs cast iron, focus should be on project requirements, with considerations such as corrosion resistance, weight, strength, and conductivity at the forefront. Other factors are heat retention and the cost of material and process.
For CNC machining projects, you cannot afford to overlook the machinability of the cast metal.
Weight/Density
A cast iron product is normally heavier than a similar cast aluminum one. This is because iron is heavier than iron, and since these metals are the main components in the respective cast versions, the status remains.
Durability
Cast iron has remarkable durability, backed by superior wear resistance and heat resistance. It particularly outperforms cast aluminum in high-temperature applications, where the low melting point of aluminum is a letdown.
Strength
A rigid cast-iron caster wheel
Cast iron has a higher compressive strength, making it suitable for bridges and other heavy-duty applications. When it comes to tensile strength, cast aluminum performs better. Therefore, consider cast aluminum for applications that require high flexibility.
Corrosion Resistance
Cast aluminum, with its naturally occurring oxide layer, is more corrosion-resistant than cast iron. Cast iron often performs badly on this front, especially in moist conditions.
Rusty cast-iron frying pan
Cost
The initial cost of cast aluminum is relatively high, mostly due to the more demanding extraction process of this material. However, the material becomes progressively cost-friendly because it is recyclable, lightweight, and corrosion-resistant.
While cast iron is more affordable initially, the weight and proneness to rust can compound costs over time.
Conclusion
With notable differences in thermal conductivity, weight, durability, cost, and other areas, cast aluminum and cast iron are built for different applications. The secret is to tap into the good qualities of each.
Are you still pondering over cast aluminum vs cast iron for your next project? You may require professional support to choose the best metal type. ProleanTech is the best partner for CNC machining and related services.
FAQ`s: Is cast aluminum cookware good?
Yes, cast aluminum cookware is good, with properties like high thermal conductivity, low weight, high durability, and cost-effectiveness.
Does cast aluminum crack easily?
No, the material does not crack easily under standard working conditions. However, it becomes more prone to cracking if exposed to stress or mishandled.
Why is cast aluminum so expensive?
Cast aluminum is comparatively expensive due to its processing requirements, which are energy-intensive. Higher precision is also required to attain a quality cast aluminum item.
How long does cast aluminum last?
Cast aluminum can last for several decades, thanks to its natural corrosion resistance and if well-maintained.
Will cast aluminium rust?
No, cast aluminum will not rust because it creates a protective layer of aluminum oxide to resist corrosion.
