An Introduction To Metalworking

Metalworking has been around for thousands of years and has evolved with advancements in technology and machinery. Nowadays, it uses Computer-Aided Design (CAD) and Computer Numerical Control (CNC) machines to create precise and complex metal structures.

The History of Metalworking

The earliest evidence of metalworking is a copper pendant uncovered in Iraq, dating back to 8,700 BCE. In ancient times, people primarily used metalworking to create tools and weapons for hunting and warfare. As metalworking techniques improved, creating more intricate designs, such as jewelry and decorative objects, became possible.

During the Middle Ages, metalworking became a highly specialized craft. People formed guilds to regulate the industry and ensure that apprentices received proper training. Meanwhile, the Industrial Revolution marked a significant advancement in metalworking technology when the steam engine and other machines enabled mass production.

In modern times, metalworking remains an important industry with many applications, including construction, transportation, and manufacturing.

Advantages

Some of the advantages of metalworking include the following:

• A manufactured product will last for a decade.
• High-volume and long-term production lines have high-cost efficiency.
• The products created from metalworking are resistant to high temperatures.
• Metalworking has a broad range of applications.
• This process also produces strong materials for various purposes.
• Metalworking fluids have advanced metalworking processes.
• Casting is a helpful method for creating tools, sculptures, and jewelry.

Disadvantages

While metalworking has numerous advantages, it is also essential to acknowledge its limitations. The following are some disadvantages of metalworking:

• Metalworking requires a skilled individual in all areas.
• The duration of a project is usually long.
• Start-up costs for metalworking processes are high.
• Knowing how the various machines work is essential before using them.
• The possibility of severe physical injury or, in worst cases, fatality always exists.
• The process of metalworking requires a large number of tools.
• Post-fabrication procedures are time-consuming and costly.

Metalworking Techniques

Metalworking techniques vary based on the properties of the metal used and can produce a range of objects in different sizes. Below are the other methods used in metalworking:

Cutting

Metal fabrication shops, automotive repair, and construction workers commonly use cutting. Milling, routing, turning, and CNC machines are some methods used to remove material from metal. While creating holes in metals, this process uses plasma cutters, which use argon and hydrogen for power.

Joining

Joining is the act of combining metal pieces through welding or soldering. Welding uses a machine to join ferrous and non-ferrous metals and is best for bigger projects. Soldering fuses precious metals by melting solder and is best for smaller projects.

Forming

Forming metal involves using heat and pressure to reshape it without adding or removing material. This metalworking technique uses two methods: forging and bending.

Forging involves heating the metal, then hammering and bending it into the desired shape. Meanwhile, bending is done by heating the metal and striking it with a hammer over the anvil horn. It uses an English wheel to shape cold materials like aluminum or steel.

Casting

Metal casting is a technique used in history for sculpting, crafting tools, and designing jewelry. The process includes pouring melted metals into different materials’ cavities. Despite its age, it remains popular due to its economic benefits, speed, and ability to create identical copies of an item.

You can cast metal using lost wax casting or sand casting. Lost wax casting involves carving in wax, creating a plaster mold, and burning out the wax. On the other hand, sand casting uses sand combined with a bonding agent like clay, and molten metal is flowed into the mold to create an object.

Cutting Processes

Metal cutting is a necessary step in metalworking for building structures and making tools. There are various methods available, ranging from handheld devices to advanced machinery.

Milling

The process of milling involves removing precise amounts of material from a larger piece by using a milling machine that rotates a cutting tool and brings it into contact with a workpiece. The mill and lathe are essential machines capable of producing pieces with high precision, repeatability, and accuracy.

Turning

Turning involves a cutting tool moving linearly while a workpiece rotates. This technique removes material from the piece in both depth and width. Conventional machine tools used for turning are lathes, but due to technological advancements, a more automated process employs CNC machines now.

Grinding

Grinding is an abrasive process used in metalworking to remove material from a workpiece. Machines used for grinding include handheld angle grinders, bench grinders, and CNC machines. Grinding machines vary in size and precision. An abrasive wheel made of stone, diamonds, or inorganic material is used for precise cuts and fine finishes.

Drilling

Drilling involves creating holes in metal using drill presses, handheld drills, or CNC machines. Ensure you lubricate your bits with cutting fluid to prolong the tool’s life and prevent overheating. It ensures a smooth and accurate hole and prevents chattering or unsafe drilling.

Joining Processes

Joining metals involves using heat and pressure to create larger pieces or build structures. Welding and riveting are effective techniques for larger projects requiring weight-bearing capacity, while soldering is used for joining smaller materials such as jewelry and sculptural objects. Here are different methods used when joining metals.

Welding

Welding involves joining materials through pressure and heat. It can be done indoors or outdoors, depending on the type. Welding is used to create swords, ships, structures, and more. Each type of welding has its practical application, as follows:

• Gas Metal Arc Welding (GMAW) – utilizes a heated solid wire electrode in a welding gun and is a viable option for beginners.
• Gas Tungsten Arc Welding (GTAW) – involves a tungsten electrode that remains intact throughout welding, enabling precise control over amperage and gas flow. This technique is ideal for delicate materials and can be used on non-ferrous and ferrous metals.
• Shielded Metal Arc Welding (SMAW) – involves a consumable electrode coated with flux to create strong welds suitable for thicker materials. This process is versatile, with easy equipment setup and a generally easy learning curve.
• Cored Arc Welding (FCAW) – uses a consumable electrode that is continuously fed and can be semi-automatic or automatic. The electrode includes a flux core that shields the weld from atmospheric elements, making it adaptable and easy to transport.
• Energy Beam Welding (EBW) – involves the generation of electrons through an electron gun and accelerating them to high speeds using electrical fields. These electrons are then focused and applied to the joined materials using magnetic fields.
• Atomic Hydrogen Welding (AHW) – involves an electric arc created by two tungsten electrodes in the presence of hydrogen gas. The arc breaks the hydrogen molecules and later recombines them through a reaction.
• Oxy-acetylene Welding – involves using fuel gases and oxygen to heat the flame and melt the material of the workpiece in a localized manner.
• Plasma Arc Welding – involves creating an electric arc between a non-consumable electrode and the workpiece. It results in high temperatures and energy concentration, creating deep and narrow weld seams at high speeds.

Soldering

Soldering involves melting a low-temperature alloy into the joint to fuse the metals into one solid piece to create a reliable electrical bridge. Metalworkers use an eclectic soldering iron or a gas-powered torch to join precious metals. Soldering is widely used in plumbing, electronics, metalwork, and even musical instrument fabrication.

Riveting

Rivets are mechanical fasteners that make joints or reinforce structures. They work best for lightweight objects needing high strength—rivets previously connected metal joints in buildings like the Eiffel Tower and Sydney Harbour Bridge. Rivets are smooth cylinders with a head before installation.

Forming Processes

Shaping metal can be accomplished through either hot or cold manipulation. The specific method will depend on the type of metal, available equipment, and desired result. The different types of forming techniques are discussed below.

Forging

Forging is an ancient metalworking process that shapes metal. The process involves heating metal in a forge and hammering and bending it. A blacksmith uses a hammer for smaller objects or an industrial power hammer for larger ones. Forged metals, commonly made of iron and steel, are known for their strength.

Roll Forming

Roll forming involves continuously bending sheet metal sheets at room temperature through a roll-forming mill. It is known for its precision, flexibility, and ability to form metals up to a quarter of an inch thick.

Rolling

Rolling is a process used to decrease the thickness of metals or achieve uniformity, which can be either hot or cold. Hot rolling is suitable for larger workpieces and sheet metal. In contrast, cold rolling is preferable for smaller objects, improving strength and surface finish and reducing the need for additional finishing work.

Casting Processes

Metal casting is used to create solid metal objects by pouring molten metal into a mold. The metal is then cooled and extracted from the mold. It’s a cost-effective and time-saving method. This section will discuss the common techniques for casting metal below:

Investment or Lost Wax Casting

An investment casting process involves pouring molten metal into a wax model mold. The mold has sprues attached and is covered with plaster. Kilns are used to burn out wax. Metal is melted and poured into the plaster mold using a vacuum or centrifugal caster.

Die Casting

A die-casting process involves injecting molten metal under high pressure into a mold. The mold comprises two machined steel dies and typically uses alloys with a low melting point, such as zinc, copper, aluminum, and magnesium. This automated process is known for its speed.

Sand Casting

A metal casting method commonly used in foundries. The mold combines sand with a bonding agent like clay and is gated. A mold is used to form molten metal into objects. Sand casting is inexpensive and the most widely used metal casting method.