What’s CNC Precision Machining? A Technical Explanation
Automotive components, medical implants, defense equipment parts, and many other applications require tight tolerances for their functionality, often as low...
Magnesium CNC Machining Service
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Magnesium in CNC Machining
Magnesium is an exceptional metal renowned for its lightweight nature and remarkable strength. It ranks as the third most widely utilized metal, after iron and aluminum, and it plays a crucial role in numerous industries. Magnesium is increasingly popular in CNC machining due to its excellent strength-to-weight ratio. It is also highly regarded for its exceptional machinability and its capability to fabricate intricate and precise components. Its superior damping capacity makes it suitable for automotive, aerospace, and electronics industries. Despite its flammability concerns, with proper precautions, magnesium offers unparalleled benefits in high-performance applications.
| Available Magnesium at RapidDirect: | Magnesium Alloy AZ31B, AZ91D |
| Price: | $$$$$ |
| Lead Time: | < 10 days |
| Wall Thickness: | 0.75 mm |
| Tolerances: | ±0.005″ (±0.125mm) |
| Max Part Size: | 200 cm x 80 cm x 100 cm |
Magnesium Alloy AZ31B
AZ31B is a highly versatile alloy with extensive applications across a range of industries. It is highly regarded for its exceptional machinability, lightweight properties, and weldability. The alloy consists primarily of 3% aluminum and 1% zinc. It provides enhanced strength compared to pure magnesium, effective vibration damping, and exceptional resistance to corrosion. It is frequently employed in constructing aircraft fuselages, camera bodies, laptop frames, and more.
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm³) |
|---|---|---|---|---|
| 180 - 240 | 100 | 6 - 20 | 50 - 70 | 1.77 |
Magnesium Alloy AZ91D
AZ91D is the most commonly used magnesium alloy. It is a high-purity cast alloy comprising 9% aluminum and 1% zinc. It is appreciated for its high strength, excellent castability, and good corrosion resistance. As a result, it is extensively utilized in automotive parts, electronic devices, and aerospace components.
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm³) |
|---|---|---|---|---|
| 150 - 160 | 90 | 3 - 7 | 60 - 70 | 1.81 |
Surface Finishing Options for Magnesium
Since magnesium parts are prone to machining defects and formation of burrs, it’s important to treat them with the right surface finishes. This will improve their aesthetic appeal and enhance performance and longevity. At RapidDirect, we offer an extensive range of surface finishing options tailored to your requirements, ensuring optimal protection and visual quality for your magnesium parts.
As machined
Magnesium can be left with a machined surface, which will show tool marks from machining.
Polishing
Polishing can be applied to magnesium to create a smooth and shiny surface, although care must be taken due to magnesium’s reactive nature.
Sand Blasting
Sandblasting is effective for removing surface imperfections and giving magnesium a matte finish, but it requires caution to prevent oxidation.
Tumbling
Tumbling can be used on magnesium to smooth and clean the surface, often resulting in a matte finish.
Alodine
Alodine is commonly used for magnesium to improve corrosion resistance and prepare the surface for painting.
Heat Treatment
Heat treatment can alter the mechanical properties of magnesium, but it may also change the surface appearance through oxidation.
Anodizing
Magnesium can undergo anodizing to improve its corrosion resistance, although special processes are needed compared to aluminum.
Teflon Coating
Teflon coating can provide a non-stick, durable surface on magnesium.
Electroless Nickel
This coating is applied to magnesium to increase wear resistance and improve corrosion protection.
Painting
Magnesium can be painted to enhance its appearance and provide additional corrosion resistance.
Powder Coating
Powder coating is a suitable method for finishing magnesium, providing a durable, protective, and aesthetic coating.
Electrophoresis
This process can be used to deposit a uniform coating on magnesium, improving corrosion resistance.
Pros and Cons of
Magnesium CNC Machining
Magnesium machining offers several advantages, making it a preferred choice for many industries. However, certain drawbacks must be considered.
Pros
- Lightweight: Magnesium is one of the lightest structural metals, making it ideal for applications where weight reduction is crucial.
- High Machinability: Magnesium’s superior machinability makes it easier to cut and shape using CNC machining processes. The material’s lower cutting forces help reduce the rate of tool wear, enhancing overall machining efficiency.
- Complex Geometries: Magnesium alloys are ideal for producing custom parts with complex geometries due to their high machinability. Multi-axis CNC machines can machine magnesium alloys from various angles, ensuring high accuracy and adherence to specifications.
- Good Damping Properties: Effective at absorbing vibrations, which is beneficial in automotive and aerospace applications.
- Recyclable: Magnesium alloys are environmentally friendly and recyclable, making them ideal for sustainable manufacturing. CNC machining magnesium generates waste that can be recycled, contributing to eco-friendly production practices.
Cons
- Flammability: Machining magnesium alloys generates fine chips and dust that are highly flammable, posing a significant fire risk. Fires can ignite due to excessive heat or sparks produced during the machining process.
- Heat Generation: Magnesium’s poor heat conductivity causes high heat concentration in the cutting zone, leading to elevated cutting temperatures. This can reduce tool life, cause workpiece deformation, and increase tool wear.
- Tool Wear: Magnesium’s relatively soft and abrasive nature accelerates tool wear compared to other metals. This results in decreased machining efficiency and increased tool replacement costs.
- Surface Deformation: Magnesium alloys are prone to burr formation and machining-induced deformation. Thus, achieving high-quality surface finishes without appropriate machining strategies and tooling selection is challenging.
Applications of
CNC Machined Magnesium Parts
CNC machined magnesium parts are widely used in various sectors due to their unique properties:
- Automotive: Used in lightweight components like engine blocks and transmission cases.
- Aerospace: Ideal for structural parts, reducing overall aircraft weight and improving fuel efficiency.
- Electronics: Common in electronic housings and heat sinks due to excellent thermal management.
- Medical Devices: Used in implants and instruments where weight reduction is crucial.
- Military and Defense: Used in military applications such as missile and aircraft components, as well as equipment housings, due to its superior strength-to-weight ratio.
- Robotics and Automation: In robotics, magnesium parts are favored for their lightweight properties and high strength, which ensure efficient movement and enhanced durability.
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FAQs
Yes, magnesium is safe for machining when proper precautions are taken. Its flammability can be managed by using specialized equipment and techniques. This includes maintaining a clean work area to prevent chip accumulation, using appropriate cutting fluids to reduce heat, and ensuring that tools are sharp to minimize friction. Fire extinguishing measures, such as having Class D fire extinguishers on hand, are also essential.
Magnesium machining offers several advantages over aluminum. It is lighter and has better machinability. It also requires lower cutting force. These allow it to be machined faster with less tool wear, resulting in lower production costs. Magnesium also has superior damping properties, making it ideal for applications requiring vibration absorption.
Magnesium parts should be stored in a dry, well-ventilated environment and away from moisture and corrosive elements. Additionally, magnesium parts should be kept separate from materials that could cause galvanic corrosion, such as steel or other dissimilar metals. Proper packaging, using materials like VCI (volatile corrosion inhibitor) paper, can also help protect against environmental factors.
Magnesium is commonly alloyed with elements like aluminum, zinc, and manganese to enhance its properties. These alloys improve strength, corrosion resistance, and machinability while maintaining the lightweight characteristics of magnesium. For example, AZ91D (magnesium-aluminum-zinc) is widely used in the automotive and electronics industries due to its good castability and strength.
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