A Popular Science Guide to Metal Materials

Basic Classification of Metal Materials

Metal materials are generally divided into ferrous metals and non-ferrous metals. Ferrous metals mainly consist of iron and steel, which account for the largest share of global metal usage and are widely used in construction, transportation, and heavy industries. In contrast, non-ferrous metals are less commonly used in terms of volume but play a crucial role in high-tech industries such as electronics, aerospace, and medical equipment.

Ferrous Metals include:

Steel: Steel is the most commonly used ferrous metal, known for its strength, ductility, and machinability, making it ideal for manufacturing a wide variety of structural and mechanical parts.
Cast Iron: Composed primarily of iron and carbon, cast iron has a high carbon content and is known for its hardness. It is often used in parts that require wear resistance and corrosion resistance, such as engine blocks.

Non-Ferrous Metals include:

Aluminum and its Alloys: Lightweight, corrosion-resistant, and easy to machine, aluminum alloys are widely used in industries like aerospace, automotive, and construction.
Copper and its Alloys: Copper has excellent electrical and thermal conductivity, making it ideal for use in electrical and electronic equipment manufacturing.
Titanium Alloys: Known for their outstanding corrosion resistance and high-temperature strength, titanium alloys are used in industries such as aerospace and medical equipment.
Brass: Composed of copper and zinc, brass is known for its good machinability, corrosion resistance, and attractive appearance. It is commonly used in mechanical components and electronic parts.
Bronze: Primarily made of copper and tin, bronze has high strength and corrosion resistance, making it suitable for applications in marine environments and machinery.
Zinc: Zinc is often used as a protective coating for other metals due to its corrosion resistance and is used in die-casting, galvanizing, and battery production.

Characteristics and Applications of Common Metal Materials

Aluminum Alloys

Aluminum alloys are lightweight, high-strength, and highly corrosion-resistant materials that have widespread applications in many industries, particularly in aerospace, automotive, construction, and electronics. The relatively low density of aluminum makes it a popular choice in industries that require weight reduction.

Key characteristics of aluminum alloys include:

Lightweight: With a density of around 2.7 g/cm³, aluminum alloys are much lighter than steel, making them ideal for use in applications that require lightweight materials, such as aerospace and transportation.
Corrosion Resistance: Aluminum alloys naturally form a thin protective oxide layer on their surface, preventing further oxidation and enhancing their corrosion resistance.
Good Machinability: Aluminum alloys have good plasticity, making them easy to machine using processes like milling, turning, and cutting. They are particularly suitable for precision parts in large-volume production.

Applications include:

Aerospace: Aluminum alloys are extensively used in aircraft and spacecraft components due to their lightweight nature and strength.
Automotive: Aluminum alloys are increasingly used in the automotive industry to reduce weight and improve fuel efficiency.
Construction: Aluminum alloys are commonly used in window frames, doors, and building facades.

Stainless Steel

Stainless steel is an alloy containing at least 10.5% chromium, which gives it excellent corrosion resistance. This makes stainless steel ideal for use in environments exposed to moisture, chemicals, or high temperatures. It also has good mechanical properties, including strength and durability.

Key characteristics of stainless steel include:

Corrosion Resistance: The chromium in stainless steel forms a protective oxide layer on the surface, which prevents further rust and corrosion.
High Strength and Toughness: Stainless steel is known for its high strength-to-weight ratio and resistance to wear and fatigue.
Variety of Grades: Different grades of stainless steel offer different balances of strength, ductility, and corrosion resistance, allowing for a wide range of applications.

Applications include:

Kitchen Equipment: Stainless steel is commonly used in kitchen appliances, cookware, and utensils due to its resistance to rust and staining.
Medical Devices: Stainless steel is widely used in medical instruments and implants due to its biocompatibility and strength.
Chemical Processing: Its resistance to corrosion makes stainless steel ideal for use in equipment for processing chemicals and food.

Titanium Alloys

Titanium alloys are known for their outstanding strength-to-weight ratio, excellent corrosion resistance, and high-temperature stability. These properties make titanium alloys particularly useful in demanding industries such as aerospace, military, and medical devices.

Key characteristics of titanium alloys include:

High Strength and Low Density: Titanium alloys are stronger than many steels but significantly lighter, making them ideal for aerospace and automotive applications.
Excellent Corrosion Resistance: Titanium resists corrosion in even highly corrosive environments such as seawater and chemicals.
High-Temperature Resistance: Titanium alloys maintain their strength and integrity even at high temperatures, making them suitable for use in turbine engines and aerospace components.

Applications include:

Aerospace: Titanium alloys are extensively used in aircraft and spacecraft components that require high strength and light weight.
Medical Devices: Due to their biocompatibility, titanium alloys are commonly used for medical implants and prosthetics.
Marine and Chemical Industries: Titanium is used in components exposed to harsh environments, such as seawater or corrosive chemicals.

Selection and Machining of Metal Materials

The selection of metal materials for CNC machining depends on several factors, including the material’s mechanical properties, corrosion resistance, and ease of machining. When choosing a material, it is important to consider the following:

Hardness and Strength: Materials with higher hardness and strength generally require more advanced machining techniques and may wear tools faster. However, they are essential for parts that need to withstand high stress or harsh environments.

Corrosion Resistance: Materials with good corrosion resistance, such as stainless steel and titanium alloys, are ideal for applications exposed to moisture or chemicals.

Machinability: Materials like aluminum and brass are easier to machine compared to harder materials like steel or titanium. The machinability of a material influences tool selection, cutting speed, and the need for coolant during the machining process.

The CNC machining process itself involves precise cutting, milling, turning, and drilling operations, which are controlled by computer software to ensure accuracy and efficiency. CNC machining can handle a wide range of materials, including both ferrous and non-ferrous metals, and is capable of producing high-precision parts.