Metalworking

For those looking to find a high quality metal processing company, they need to look no further than Vestavia. Vestavia provides the very best quality metalworking. For over 10 years Vestavia has been the leading metal processing company in Riga, Latvia, and we can provide the kind of service and expertise to meet your needs.

Metalworking has a long history and has grown fundamentally in many ways since it first began. It requires a metal processing company that understands the history of this industry to be able to provide premium services, and Vestavia is just that company.

Metalworking

Metalworking, the process by which metals are used to create parts, assemblies, or large-scale structures, is a wide ranging section of work that encompasses everything from air craft carriers, towers, and bridges to small engine parts and even jewelry. Because of all of the different things that can be made, there is a wide range of skills, processes, expertise, and tools that are needed, and this is why metalworking has become a very specialized occupation.

Metalworking is much more than just an occupation. It is an art, a science, an industry, and a trade all rolled into one. The history of this craft goes back for thousands of years, across all continents and cultures, and has been one of the most important trades that the world has ever seen. As processes and skills have developed it has moved from one of the most diverse and specialized kinds of works that a person can get into. In today’s machine shops there are a large number of different kinds of machine tools that are specialized to work on differing types of work pieces, performing incredibly precise work.

Prehistory

It appears that the earliest use of copper mining that archeologists have been able to record dates back to 8700 B.C. A copper pendant was discovered in northern Iraq and has been recorded as the oldest piece of copper work. North America’s earliest known copper piece dates to between 5000-4000 B.C. where pieces of copper were hammered in the Wisconsin area near what is present day Lake Michigan. Copper appears to have been used long before one of the most popular precious metals – gold. The oldest gold artifact is dated to about 4450 B.C. and was discovered in Varna Necropolis in Bulgaria.

While there are a large number of elements that fall into the class of metal, writer/scientist Isaac Asimov writes that gold should be considered the “first metal.” Asimov based his reasoning on the fact that gold is found in nature as it naturally exists, as a nugget. No work is needed to separate gold from other elements; it simply exists as itself. Not many other metals exist this way in nature, because they are often found in ores, a type of mineral bearing rock that requires some kind of work or reaction to separate it from other compounds.

Gold’s properties make it one of the easiest to work with. Its high malleability and ductility make it easy to mold into any shape needed, even used stone or wood tools. This is why it became so popular in early civilizations.

As cultures developed and technologies improved, different societies began to figure out that heat could be used to liberate the metals from the ores. Soon, rocks that were high in copper, lead, and tin became available for use. This opened up a great many societies to start using these metals, and it did not take long for weapons, pottery, machinery, and even homes to become sturdier. Mines where these ores were found have been found all over the world. Metalworking has been performed in South Asia since 7000-3000 B.C. by the Mehrgarhs. Copper smelting has been found in the Middle East in about 6000 B.C.

Many ancient civilizations have used seven important metals for over 5000 years. The seven primary ones are iron, lead, tin, copper, silver, gold, and mercury. The oxidation of these seven metals ranges from +0.44 V to -1.50 V, and it is these values that played a significant role in the use of the metals. Oxidation potential is a significant factor in how well an ore is bonded to the metal. For example, gold has a much lower oxidation which is why it is found separated in nature. On the other end of the spectrum, iron is much more difficult to remove from ore, because it is much more tightly integrated within the ore.

What makes copper, and tin as well, so important is that it is found in such high abundance. It was very hard to use copper until it was discovered that heating would help to remove the copper smelt from the ore. Once this was discovered copper began to be used in great abundance.

The one problem with copper was that it was very soft and brittle. This made it great for use in making jewelry and very simple tools, but it did not have the stiffness to be used in much higher grade work. To augment this, copper was mixed with tin to make bronze. The combination of the two gave the required stiffness that was desired, while also maintaining much of the malleability and durability that copper had on its own. This made it ideal to create heavier tools and weapons, but to do it with less work than using heavier grade metals.

It was not just in the Middle East that these advances were found. All over the world bronze became the “metal” that was used for a majority of tools and weapons. China and Britain were two of the areas where this was found early on. Around 2700 B.C. bronze was found in any area where they had learned to use heat to remove the metal from ore. It would not be long before cultures moved from copper to iron.

History

In the third millennium B.C. when history was first being recorded, records show that civilizations in Egypt, India, Israel, and North America were using precious metals. There were even laws and trade agreements that were created that governed ownership, trade, and distribution of these metals.

Trade led to the development of skilled metalworkers who were able to extract and mold many forms of metal to be used in a wide variety of ways, including jewelry, tools, weapons, pottery, and structures.

The skills of these craftsmen became more specialized as the years went by. Techniques developed that created the need for artisans, blacksmiths, alchemists, atharvavedic practitioners, and other groups of metal specialists. Often this meant that trade was necessary to gain the specific work that was needed and, thus, metals became one of the primary reasons why trade developed between differing cultures.

As the centuries went by metals became very common and the things that were created with metal became more complex. Because so many things were created using metal, these elements became more important, and thus the skills related to working with metals became essential and evolved. Metalsmiths not only found new ways to extract metals more quickly, but also ways to use it. Many civilizations became huge powers out of their ability to work with and create needed objects out of metal.

The need for metal is just as important now as it was 2000 years ago. Metal is used in so many objects today from computers, to planes, to appliances, to jewelry. The work and creations of early metalsmiths set the foundation of what is created and used today.

General Metalworking Processes

There are three primary classes that metalworking is divided into: forming, joining, and cutting. In each of these categories there are different processes that are undergone to develop or create pieces.

Within the metalworking process there are two very important terms that are important to understand. The first of these is “marking out” (also called layout). In this process there is a transferring of the pattern or design that is desired onto the work piece as the primary step in the initial creation. This is performed in big industrial work as well as in hobby work. In many of the metal trade areas marking out is commonly used to transfer the design of an engineer’s plans onto the work piece before the manufacturing process begins.

The second term is “calipers.” Calipers are hand-tools that are specifically used to measure the distance between two points on a work piece with great precision. In a majority of calipers there are two sets of flat, perpendicular edges that are used to measure both the inner and outer diameters of the work piece. Calipers are created to give differing measurements to accommodate the needs of users.

Sheet (and Tube) Forming Processes

There are many forming processes that involve mechanical force that can be performed at room temperature. Not all processes are performed in this way, as some involve the heating of the dies or the parts themselves. Mechanical force forming processes include such things as coining, hydroforming, spinning, raising, bending, incremental forming, roll bending, rubber pad forming, flowforming, and decambering, among others.

Cutting Processes

Cutting is not a single process, but is actually many processes where material is created to meet a very specific geometrical configuration while removing the excess material on the work piece. These processes use a variety of tools to meet the specific design. In using the cutting process there are two products that are left: waste and the finished part. Waste comes in the form of chips (called swarf).

Within the cutting process there are three primary categories:

• Machining – this is a chip producing process. One of the most common forms of a chip producing process is drilling.
• Burning – this is a set of processes where the metal is cut using a process of oxidizing a kerf to separate the specific pieces of metal on the work piece. The most common form of burning is by using an oxy-fuel cutting torch which allows the user to separate a single plane of steel into smaller pieces.
• Other/Miscellaneous Processes – these are processes that don’t fit easily into any of the other two categories. A very common form of a specialty process is chemical milling, which is used to remove excess material from the work piece by using etching or masking chemicals.

To cut metals there are many different technologies that can be used.

• Manual technologies: these include such things as chisels, shears, saws, and snips
• Erosion technologies: use of a water jet, abrasive flow machine, or an electric discharge.
• Machine technologies: these include drilling, grinding, milling, turning, and sawing.
• Welding/Burning technologies: this includes oxy-fuel burning, plasma, and laser.

Cutting fluid is used in situations where there is heat and a significant amount of friction at the interface of the work piece and the cutter. During the process coolant is introduced by a spray across the face of the work piece. This decreases the friction and the temperature where the cutting tool interfaces with the work piece. This prevents wear on the tool.

Milling

Milling is a process that allows the user to create a complex shaping of the metal work piece by removing material from the piece to form the final, desired shape. This is usually done on a milling machine. A milling machine is a power-drive device that helps to create the form that is desired using a milling cutter that rotates on a spindle much in the same way that a drill operates. This work is done on a worktable, which allows the user to move the table in two dimensions to complete the work. The two most common types of milling machines are horizontal and vertical, and they can be operated manually or through a computer numerical control (CNC).

The work pieces that are created with the milling cutter produce complex 3-D pieces that are produced from the X, Y, and Z-coordinates on the design, so that the job can be done to the specifications of the user. While most pieces can be directly created using the CNC machine, there are some instances where the table must be adjusted manually to ensure that tolerances on pieces remain in the thousandths of an inch (this unit is referred to as the Thou).

Many different types of materials can be milled, including aluminum, copper, tin, and stainless steel. The material determines the speed at which the milling tool is run. Each pass of the tool can only remove so much material depending upon the type of material being milled. Harder materials must be milled at much slower rates meaning that smaller amounts of material are returned with each pass.

In determining costs of creating the work piece there are factors that must be considered. The type of material being milled adds cost, as harder materials must be run through the milling cutter more times. This also means that additional coolant will be needed to prevent damage to the cutter, which will also add to the cost.

Turning

For consumers looking for the production of a cylindrical surface with a single-point cutting tool turning in the metal cutting process is preferred. During the process the work piece is rotated while the cutting tool feeds into the piece radially and/or axially via the spindle. If pieces are produced perpendicular to the axis of the work piece they are referred to as faces. If the surface is produced both radially and axially then it is called profiling.

One of the primary kinds of turning machines is the lathe, which spins a block or cylinder into a finished product. Several different kinds of processes can be used to mold the piece, including cutting, abrasion, and deformation. Lathes are used to create many different kinds of work pieces including such things as candlestick holders, bowls, bearings and bearing mounts, baseball bats, camshafts, and table legs.

There are three main components to the lathe machine:

• Headstock – the spindle of the headstock is used to secure the work piece with a jaw-like structure called a chuck. During the lathing process the spindle rotates around the axis at a very high speed, which gives the energy needed to cut the material. Most modern lathes use electrical motors to perform the action.
• Carriage – the carriage is the platform which is moved either parallel or perpendicular to the rotational axis. This is done in a very precise manner using computer generated settings. The cutter moves around the work piece as it rotates while the cutting tool shaves the materials off of the work piece.
• Tailstock – the tailstock is slid directly along the rotational axis and is locked in place as needed. This helps to keep the work piece secure, allowing the cutting tools to be driven into the work piece ends.

There are many other types of procedures that can be performed using the lathe with a single point tool. These include:

• Chamfering: This procedure cuts the work piece at an angle on the corner of the cylinder.
• Parting: during the procedure the cutting tool is fed radially so it is able to cut off end parts of the work piece.
• Threading: during this process the tool is fed both along and across the inner and outer surfaces of the parts as they rotate. This produces both internal and external threads.
• Boring: in this process a single-point tool is fed into the axis of rotation both in a parallel and linear manner.
• Drilling: the work piece has the drill tool fed into it axially.
• Knurling: this procedure creates a pattern on the work surface that is cross-hatched, making it easy to be gripped by hand.

In today’s CNC lathes and machining centers it is quite common to see milling used along with other driven tools. Driven tools stop the rotation of the work piece, and the tool itself actually does the cutting using its own rotational spin to do the work. These CNC machines still use X, Y, and Z-coordinates so that the turning tools are able to create the finished product. This allows them to easily create 3-D objects to fit the customer’s needs.

Most often the best materials used in turning are softer metals, although harder metals can be used as work pieces, but they take longer to create the end product. One note on this is that the cutting tool must be harder than that of the work piece. If it is not the cutter will be damaged because it will be unable to create the desired work. Increasing speed will not have any affect.

Threading

There are a wide variety of threading processes, which include the use of a tap or die to cut threads, using milling to create a single-point thread for cutting, and rolling, grinding, and forming threads. A tap is used when a work piece needs to have a female thread cut into the inside surface of a hole that has already been drilled. A die is a male thread that is cut into a cylinder rod.

Grinding

The grinding process is used to remove materials from the work piece, using an abrasive process. There are several different types of grinding, including the use of a grinding machine. This is a machining tool that is often used for very fine finishes. It makes very light cuts with each pass, operating a very high rate of precision with each cut. The wheels consist of different sizes, and are made primarily of stone or diamond types.

The most basic types of grinders are the bench grinder or the hand-held angle grinder. These can be used for deburring parts and are extremely proficient in cutting metal using a zip disc.

Grinders have dramatically changed over time. In the early days the manual grinders were mainly used for sharpening, but now there are 30,000 RPM CNC machines that create highly specialized pieces including such things as jet turbines.

If a grinder is going to produce the kind of finish that is desired, then it must be very rigid. In the early years grinders had severe limitations and so they were primarily used for finishing operations. In more modern times different materials are now used as cutters, including diamonds, which have greatly increased the amount and types of work that grinding machines can be used for. These more modern machines with advanced grinding techniques and higher removal rates have made grinding ideal for aerospace related applications.

Welding

The most common way of fabricating materials together is welding. Welding usually combines metals or thermoplastics through a coalescing process. The process works by melting a filler material to the work pieces creating a molten pool that as it cools creates a hardened joint. Sometimes these joints can be created through pressure along with heat.

There are many different types of energy sources that can be used in creating welds. These include flames from gas, electric arcs, electron beams, lasers, ultrasound, and friction. Welding is often used in industrial work, but it is used in many operations beyond the industrial world. Whatever the operation that is being performed, welding should be done by professionals in an environment where the highest safety standards are being observed.