Materials Handbook

Steel, also known as carbon steel, is one of the most versatile and widely used materials in sheet metal fabrication and cnc machining. steel is an alloy of iron and carbon, with varying types of steel containing different ratios of the elements to allow different tensile and durability properties. In sheet metal, steel typically comes in either hot-rolled and cold-rolled variants.

Hot-rolled steel is produced by heating steel above its recrystallization temperature (typically over 1700°F) and then rolling it into sheets. This process makes the steel easier to shape and form in sheet metal fabrication where the menufacturing process may include complex manipulations and geometries. The resulting hot-rolled steel is characterized by a rougher surface finish and a slightly larger grain structure, but it is highly durable, strong, and cost-effective. This makes it suitable for a wide range of applications, including structural components, automotive parts, and heavy machinery.

After hot rolling, the steel can undergo additional processing to become cold-rolled steel. In the cold-rolling process, the steel is further processed at room temperature, which increases its strength through strain hardening and enhances its surface finish and dimensional accuracy. Cold-rolled steel offers tighter tolerances, a smoother surface, and improved mechanical properties compared to its hot-rolled counterpart, making it ideal for applications where precision and aesthetic quality are critical, such as in the manufacture of home appliances, metal furniture, and smaller structural components. The choice between hot-rolled and cold-rolled steel in sheet metal fabrication ultimately depends on the specific requirements of the project, including the need for precision, surface quality, and budget considerations.

Steel is often used in CNC machining because it is stronger and tougher than stainless steel, but it is also easily machined and welded, and it can be heat treated to improve its strength and durability. Energy-conscious manufacturers also choose carbon steel because it requires less energy to produce than other metals and is easy to recycle. Carbon steel is commonly used in machining to create small mechanical parts like nuts, bolts, and gears. It is also used for many infrastructure and transportation projects, like in the construction of railway tracks, bridges, and buildings.

Stainless steel is an iron alloy known for its many durable and versatile properties, making it a preferred material for sheet metal fabrication and CNC machining. While both manufacturing methods leverage the strengths of stainless steel, such as high weldability, strength, and resistance to corrosion and oxidation, the way stainless steel is used in sheet metal fabrication differs from its application in CNC machining.

In sheet metal fabrication, stainless steel is used to create larger, flat or curved structures. The material’s durability and resistance to corrosion make it ideal for fabricating parts that need to withstand environmental conditions, such as exterior panels, enclosures, and housings in industries like ICT, aerospace, construction, and automotive. These applications typically focus on creating robust, lightweight components that maintain their integrity over time.

On the other hand, CNC machining of stainless steel involves the precise removal of material to create complex, high-tolerance components. This process is particularly beneficial for producing intricate parts that require detailed features, such as threaded holes, slots, and complex geometries. In the medical industry, for example, CNC machining is used to produce stainless steel components like surgical instruments, implants, and precision devices where accuracy, smooth finishes, and durability are critical. Stainless steel allows for tight machining tolerances and fine detailing, making an ideal choice for parts that must meet stringent specifications.

Aluminum is a lightweight metal prized for its corrosion resistance, strength, and durability, making it a go-to material for both sheet metal fabrication and CNC machining. While aluminum is widely used across various industries, its specific applications and the methods used to shape it can vary significantly depending on whether it is being fabricated as sheet metal or machined into precise components.

In sheet metal fabrication, aluminum is often chosen for its excellent strength-to-weight ratio and its ability to resist corrosion, making it ideal for creating large, lightweight structures and panels. Aluminum sheet metal is commonly used in many industries, including transportation & aerospace, where its lightness contributes to fuel efficiency and ease of handling without compromising on strength. Aluminum is often formed into panels, enclosures, and structural components, such as vehicle body panels, fuselage sections in aircraft, and building cladding. Aluminum is also preferred for outdoor applications, ensuring long-term performance with minimal maintenance.

In CNC machining, aluminum is touted for its high machinability and ability to hold tight tolerances, making it perfect for precision when producing intricate parts. Aluminum 6061, for instance, is one of the most commonly used alloys due to its versatility, weldability, and ease of machining. This alloy is ideal for creating parts that require a balance of strength and weight, such as aircraft components, automotive parts, and computer hardware. Its ability to undergo various heat treatments adds to its adaptability, making it suitable for a wide range of applications. For more demanding applications, particularly in the aerospace industry, aluminum 7075 is often used. This alloy is known for being the strongest commercially available aluminum, offering exceptional strength and fatigue resistance, which is crucial for aircraft components that are subjected to high stress.

Brass is an alloy of copper and zinc, and is commonly chosen due to it's malleability, general softness, and low melting point. It is more durable than aluminum and holds up well in more stressful environments over time. Brass can be manufactured with a very small tolerance making it a perfect fit for parts and components that require a high degree of accuracy. Brass is often used in CNC machining to make tools like screws and rivets, musical instruments, medical parts, and electronic components. When manufactured using sheet metal fabrication methods, brass is found in many aerospace & defense applications, including maritime, aircraft, and automotive plates and parts. 

Bronze is an alloy of copper and tin, which provides the material with features including increased durability, corrosion resistance, electrical conductivity, anti-microbial properties, and friction resistance. This alloy can be more expensive to produce than some other steel-based materials, but it offers different uses which allows it to stand out in specific applications. In CNC machining, bronze is often used for precision pieces, especially in settings that may require movement or friction like in bearings, sprockets, or gears. In sheet metal manufacturing, bronze is usually used in specialty applications where it's specific properties are highlighted. This may include medical applications due to it's anti-microbial properties, or electrical manufacturing where it's conductivity is needed.

In its pure form, copper is a soft, malleable metal with high thermal and electrical conductivity. It is resistant to corrosion and bacteria, so it is ideal for long-term use in many different environments. Pure copper is commonly used for manufacturing electrical equipment and wires. The presence of other elements like tin, nickel, and zinc makes copper more machinable, and copper alloys such as bronze and brass are more common in machining components.

Titanium is considered one of the strongest metals, and, although expensive when compared to other materials, it is one of the most popular metals used in CNC machining. That’s due to its strength, resistance to corrosion, ductility, and machinability. It is often used for demanding projects in aerospace, military, and industrial manufacturing. Because it is biocompatible (nontoxic and not rejected by the body) it has many medical uses, including surgical implants and medical instruments.

CNC machining can be a useful method when working with plastics because it is more precise than injection molding, can offer a smoother finish, and is more compatible with a wide range of materials. Plastics are often used when building prototypes or as a method to test designs. Nylon, a thermoplastic that becomes moldable when heated and then solidifies when cooled, is often used as a substitute for metals because it is tough, impact-resistant, and elastic. It is used to make electrical molding, mechanical parts, fabric, and fuel system components.

In injection molding, molten plastic materials are injected into a custom-designed metal tool inside an injection molding press. The material is then cooled through a variety of engineered cooling channels and then finally opened up and the part is ejected. In injection molding, there a myriad of different engineering-grade and commodity-grade resins that hold different properties that can be used for different purposes depending on the end-product.