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Picking the right method to process aluminum is very important to get the material properties and project results you want. If you work in aerospace, cars, or precision engineering, knowing the differences between machined and cast aluminum can give you an edge. It can help you cut costs and make better products. Today we will see what these machined and cast aluminum are, their alloys and the main differences between these two aluminums.
What is Machined Aluminum?
Machined aluminum parts are made by using subtractive manufacturing processes. These procedures involve removing substance from a solid aluminum block using computer controlled machines and precision equipment. They result in custom-shaped and highly accurate parts that have extraordinary surface finish and dimensional stability.
Common Aluminum Alloys
When it comes to aluminum alloys for machining, there are many available options. Every alloy has particular properties suited for different uses:
Aluminum 6061
6061 aluminum gives better weldability and corrosion resistance. It’s a go-to choice in marine, aerospace and car industries for key parts like boat hulls and plane bodies.
Aluminum 7075
7075 sets itself apart due to its extraordinary fatigue resistance and strength-to-weight ratio. Aerospace engineers prioritize it for aircraft structures. It’s also popular for high stake sports machinery production such as climbing gear and bicycle frames.
Aluminum 2024
It provides better machinability and high strength. 2024 aluminum is mostly used in fuselage parts, aircraft structures and automotive components where resisting wear and tear is critical.
Processes Involved
Machined aluminum undergoes different subtractive production methods to get accurate structures and shapes. Main processes involved are:
- Milling: Rotating multi point cutters to remove substance.
- Turning: Shapes cylindrical parts by rotating workpiece against a cutting tool.
- Drilling: This creates holes using rotating drill bits.
- Boring: Enlarges existing holes with single point cutters.
- Reaming: Promotes hole finish and fine tuning.
- Tapping: Cuts internal threads in the holes.
What is Cast Aluminum?
Cast aluminum is manufactured by pouring molten aluminum into molds. It is then cooled until hardened. This process yields complicated parts with outstanding corrosion resistance, thermal conductivity and strength to weight ratios. Industries such as automotive, consumer electronics and aerospace mostly use cast aluminum alloys like A356 and A380. These alloys give a balance of cost-effectiveness and performance in these fields.
Common Alloys
Now we will look at some common alloys of cast iron.
A380
A380 gives better pressure tightness and fluidity. Automotive manufacturers mostly select this alloy for making cylinder heads, engine blocks and transmission cases. Its tensile strength can reach up to 330 MPa.
A383
Aluminum A383 alloy shines in intricate structures and thin walled castings. Small engine parts, electronic housings and lighting fixtures mostly use this alloy. A383 has a 96.2 W/m·K thermal conductivity which is appropriate for heat sensitive operations.
A360
A360 get used in architectural elements, marine hardware and food machinery because of its good machinability and resistance to corrosion. This alloy mainly has 170 MPa yield strength.
Casting Methods
Aluminum casting uses different methods, each fit for particular uses. The primary processes are sand casting, die casting and permanent mold casting.
Die casting assures fast creation and high accuracy and sand casting offers versatility for complicated shapes. Permanent mold casting keeps a balance between quality and affordability for medium-sized production runs.
Main Differences between Machined and Cast Aluminum
Cast and machined aluminum differ a lot in many aspects which make them suitable for different applications. Let’s look at the main differences between these two.
1. Durability and Strength
Machined aluminum generally outshines cast aluminum in durability and strength. For example, 7075-T6 machined aluminum reaches a tensile strength of 572 MPa and A380 cast aluminum has 330 MPa tensile strength. This difference is very important in aerospace applications such as wing spars.
2. Production Process
CNC milling and other subtractive processes manufacture machined aluminum parts that can attain ±0.0005 inch tolerances. On the other hand, cast aluminum depends on additive techniques such as die casting which gives cycle times of as little as 30 seconds.
3. Weight Considerations
The porosity of cast aluminum causes lower density compared to machined aluminum. A380 cast alloy density is 2.76 g/cm3 while density of 6061-T6 machined aluminum is 2.70 g/cm3. This variation affects weight sensitive operations in automotive and aerospace industries, particularly for structural parts and engine blocks.
4. Efficiency and Speed
Cast aluminum excels in high volume production. Die casting can fabricate up to 400 parts per hour. Machined aluminum is slower but gives better accuracy for critical medical and aerospace components.
5. Looks and Surface Finish
Better surface finishes are machined aluminum’s trademark. It usually reaches 0.2 μm Ra values. Cast aluminum generally has rougher surfaces (Ra 1.6-6.3 μm) but permits complicated designs in automotive and aerospace parts such as turbine housings and engine blocks.
6. Design Flexibility
Cast aluminum facilitates complicated designs such as auto engine blocks. Machined aluminum, while more limited, gives amazing precision for aerospace parts. Cast aluminum parts can get 0.5mm thin walls. On the other hand, machined aluminum can reach a minimum 1.0mm wall thickness.
Cost and Economic Considerations
The choice between machined and cast aluminum depends heavily on their costs. Let’s look at the prices of each process:
Machining
CNC machining of aluminum mostly runs at $35 to $50 per hour for 4 or 5-axis uses. Intricate car parts can cost even more, but their prices generally drop with larger quantities production.
Casting
For complicated parts such as cylinder heads and engine blocks, aluminum casting is a cost-effective procedure. Die casting can produce up to 400 parts per hour with tooling expenses ranging from $3,000 to $100,000. This is based on production volume and intricacy of parts.
Tooling and Material Waste
Machining produces large material waste by removing up to 90% of the original block for complex aerospace parts. On the other hand, casting uses 90-95% of the molten aluminum and reduces waste. While die-casting tools can cost $50,000-$100,000 and CNC tooling is generally cheaper but needs more frequent replacement.
Maintenance and Durability
Cast aluminum’s better corrosion resistance contributes to its longevity and low maintenance needs. Machined aluminum is well-built but may require periodic surface finishes. In aerospace uses, cast aluminum parts mostly last 20 to 30 years while machined aluminum parts generally need replacement after 10 to 15 years of use.
Applications and Industry Use-Cases
Both machined and cast aluminum are broadly used across different fields. Here’s an overview of their main application:
1. Machined Aluminum Applications
Aerospace
The aerospace sector is based heavily on machined 7075 and 2024 aluminum alloys. Their fantastic strength to weight ratio makes them very important for wing spars, bulkheads and fuselage frames.
Sports Equipment
Machined aluminum’s strength-to-weight ratio helps in the production of sports equipment. Tennis racket frames, golf club heads and bicycle frames take advantage of its properties.
Automotive
Machined aluminum shines in automotive uses. Transmission cases, engine blocks and cylinder heads benefit from its accuracy.
Medical Devices
Machined aluminum is used in medical tools owing to its corrosion resistance and biocompatibility. Prosthetics, imaging device housings and surgical tools mostly utilize this aluminum.
Precision Engineering
High-precision measuring tools, semiconductor manufacturing machinery and optical mounts usually use machined aluminum parts. These use machined aluminum parts for their thermal characteristics and structural stability.
2. Cast Aluminum Applications
Automobile
Automotive industry utilize A380 alloy for cylinder heads, engine blocks and transmission cases. It’s thermal properties and strength make it perfect for these parts.
Aerospace
Spacecraft manufacturers use A380 alloy for heat shields and structural parts. It’s great for rocket engine parts and satellite frames because it’s light, strong and can handle heat up to 350°C.
Aviation
A380 alloy is widely used in aviation for landing gear parts, engine housings and structural supports. Its remarkable 47,000 psi tensile strength makes it a top selection there.
Power Electronics and Weapons
In weapons systems, A380 alloy is used for grenade launcher housings and rifle stocks because it’s strong but doesn’t weigh much. For power electronics, cast aluminum heatsinks in military radios dissipate heat efficiently and help maintain optimal operating temperatures in extreme conditions.
Conclusion
Machined and cast aluminum each have their own benefits, fitting different industry needs. Machined aluminum shows better strength and accuracy while cast aluminum gives budget-friendly solutions for complicated shapes. Knowing these differences is very important for picking the right process and material for your project.
As an experienced custom parts manufacturer, Richconn has extensive experience in machining aluminum parts. You can contact us anytime to start your next project!
FAQs
1. How production volumes influence the selection between cast aluminum and machined aluminum?
For smaller batches (up to thousands of parts), machined aluminum is generally prioritized because of its lower starting costs, faster setup and flexibility. But for high volumes, cast aluminum is usually more economical. Its higher initial cost is offset by faster production rates and lower production costs per part.
2. What environmental factors should be considered when selecting between machined and cast aluminum?
Key environmental factors that affect the selection between machined and cast iron are material waste, recyclability and energy consumption. Cast aluminum usually needs less energy for production and produces less waste. But machined aluminum lets easier recycling of scrap material.
3. What are the common challenges faced during the casting and machining of aluminum?
Common difficulties faced during aluminum machining and casting include tool wear, heat buildup and the formation of burrs.
