Metalworking History

Metalworking has been a pillar of the development of modern society. Of special importance to us, its use has been critical to building and repairing firearms. It could be argued that metalworking started more than a million years ago, when early humans learned to control fire, however, there is no obvious, definitive moment around the discovery of forging that any historian can point to. Metalworking is the product of along evolutionary process spanning centuries.

A first beginning was around 10,000 years ago when people in early Mesopotamia began working with copper. This metal would be the go-to material for weapons and other durable goods in ancient Egypt, Greece, Rome, China, and India for thousands of years. Eventually, likely by accident, people learned that smelting copper with tin made a stronger material, It now stands in the Qutb complex at Mehrauli in Delhi, India. The structure is famous for the rust-resistant composition of the metals used in its construction.

It is thought to have been erected elsewhere, perhaps outside the Udayagiri Caves and moved to its present location by Anangpal Tomar in the 11th century. Far This method was used in blacksmithing even in the 20th century. bronze. Early weapons fashioned from this have been found in the Balkans region determined to be up to 7,000 years old. Brazing is believed to be about 5,000 years old when Sumerians made swords by hard soldering and Egyptians pressure welded metal by hammering.

Early iron making has been discovered to be about 4,000 years old, with early examples discovered in India and from the Hittites of ancient Egypt. Early examples of steel, with iron ore heated in a furnace and hammered into shape, is at least 3,500 years old with examples discovered in Sub-Saharan Africa.

Many historians believe that these early Africans had built blast furnaces that could reach temperatures hotter than anything achieved in Europe until the Industrial Revolution, however, they lacked sufficient fuel (wood to create charcoal) for extensive use.

Historians also believe metalworkers in China developed a method for blasting heated iron ore with air to remove impurities via oxidation about 1,000 years ago, centuries before Sir Henry Bessemer would patent the similar process that bears his name and makes steel by using a cold blast of air over molten metal. As metalworking became better known and more refined, bigger projects became possible.

One early example is the Iron Pillar of Delhi, believed to be the largest weldment ever at the time and for years after. Built nearly twenty-four feet in overall length and weighing more the three tons, the monument to Vishnu near Delhi was manufactured by forge welding pieces of wrought iron. Despite being over 1,600 years old and having once been hit with a cannon, the pillar has a high degree of corrosion resistance and continues to be studied for its insight into the sophistication of early metalworking.

The forging and other processes used to construct the Pillar continued to serve as the basis of forging into the twentieth century. By the 1800s, smiths had become skilled at open die wrought iron forging, a process that required great heat, meaning smiths needed to also become proficient in hammer welding. This provided the means to manufacture the mechanisms leading to the Industrial Revolution, such as the steam engine. With a reliable source

1, Coating Flow; 2 Rod; 3, Shield Gas; 4. Fusion; 5. Base metal; 6. Weld metal; 7. Solidified Slag. The process may or may not require the use a filler material. External application of pressure is not required for fusion welding processes, except for resistance welding, where substantial contact pressure is required during welding for sound joining.

Gas tungsten arc welding (GTAW), Gas metal arc welding (GMAW or MIG), Plasma arc welding (PAW), Electrogas arc welding (EGW), Carbon arc welding (CAW), Bare metal ARC welding (BMAW), Shielded metal arc welding (SMAW), Submerged-arc welding (SAW), Flux cored arc welding (FCAW), Flash welding (FW), Arc stud welding (SW), Percussion welding, (PEW), Electroslag welding (ESW), Resistance spot welding (RSW), Resistance seam welding (RSEW), Projection welding (PW), Electron beam welding (EBW), Laser beam welding (LBW), Flow (cast) welding, Induction welding (IW), Oxyacetylene welding (OAW), Oxyhydrogen welding (OHW), Air acetylene welding (AAW), Thermite welding (TW) of high amounts of power, workers could produce even more tools and products for old and new industries.

The Bessemer process helped as well, making it easier to smelt iron ore into high-quality steel. In the early 1800s Edmund Davy, an Irish chemistry professor, discovered the gas now known as acetylene by accident when experimenting with potassium. His cousin, Humphry Davy, was also a chemist and discovered how to use a battery to create an electric current between two carbon electrodes. Both were critical to improving welding and their developments are concepts still used.

Gas welding, brazing, and cutting with oxygen or hydrogen came into their own in the late 1800s. The massive manufacturing spurned on by World War I would show the cost and efficiency of welding compared to riveting. Ships were being built in the U. S. and Europe using arc welding and the huge increase in use called for definition and standardization of welding language and usage. In 1919 the American Welding Society was formed by the Wartime Welding Committee with Comfort Avery Adams leading the effort.

While there is some dispute around how this modernized into shielded metal arc welding, several developments in electrode technology occurred around this same time. The coated electrode development is credited to the A. O. Smith Company and it was used extensively by the late 1920s. Lincoln Electric began mass producing coated electrodes utilizing an extrusion for the coating rather than dipping. The coating improved the usability of the electrodes and shielded the molten puddle from the oxygen/nitrogen atmosphere.

By the 1950s, the Linde Air Products Company marketed constricted arc cutting. Until it was overshadowed by plasma cutting, this was the best way to sever nonferrous materials by using a gas tungsten arc torch and a high-pressure regulator placed on a separate argon cylinder. Contamination was minimal but the grinding was not and argon was expensive. Airco (Air Reduction Company) is credited with creating the gas metal arc welding (GMAW) process, also known as metal inert gas (MIG) welding.

Initially, use of inert gases for welding on carbon manganese material was thought to be too expensive, so CO2 (a non-inert gas) was used as it also produced suitable shielding and penetration into the base material and remains the norm. Since then, various gases

Above and The workpiece was turned by a rope moved via a bow or foot pressure against a spring pole or treadle. as well as mixed gases have made it possible to weld almost all ferrous and nonferrous metals. Each invention or improvement has created means for new kinds of and/or easier fabrication. Automatic processes are being used in large shops with positioners that turn in varying configurations. Such fixturing enables most welds to be made in the flat position, enhancing speed and weld quality.

While beyond small shop and gunsmithing work, robots have become more versatile for general fabrication, even when not used for repetitive welding. Software that is readily adapted to almost any weld type or shape aids in quick changes from one weldment to another with the click of a mouse. A cutting tool is used to remove small chips of material from the workpiece. Relative motion is achieved in most machining operation by means of a primary motion, called "cutting speed", and a secondary motion called "feed".

The shape of the tool and its penetration into the work surface, combined with these motions, produce the desired shape of the resulting work surface.. Machining Machining is a process in which a material (often metal) is cut to shape and size by a controlled material-removal process. This is usually subtractive manufacturing, where material is removed from a workpiece in a controlled manner until the final shape is created. How this is controlled is dependent on the tool.

As with many technologies, precise meanings evolve with developments. In the 1700s, a machinist described craftsmen that built or repaired machines. This was almost always bespoke work done by hand, such as by carving or filing. By the 1900s, a machinist described a person conducting what we now consider "traditional" processes on workpieces such as drilling, milling, turning, tapping, planing, etc. It would also imply use of machine tools such as lathes, milling machines, drill presses, and the like.

The three principal machining processes are turning, milling, and drilling. Turning operations are operations that rotate the workpiece as the primary method of moving metal against the cutting tool. Lathes are the principal machine tool used in turning. Milling operations are when a tool rotates to bring cutting edges to bear against the workpiece with milling machines being the principal ones used.

Drilling operations are when holes are produced or refined by bringing a rotating cutter with edges at the lower extremity into contact with the workpiece. Drilling operations are done primarily in drill presses but sometimes on lathes or mills. An unfinished workpiece requires having material cut away to

The ML7R was first launched in 1917, not to be confused with the ML7. create a finished product based on blueprints or measurements taken, such as making a replacement part. Around workpiece needing a specific outside diameter could be turned on a lathe against a cutting tool to create a smooth, round surface. A drill can be used to remove metal in the shape of a cylindrical hole, especially boring down the Zaxis. A mill typically spins a tool to cut sideways along the Xand Yaxis of the workpiece.

Computer Numerical Control can greatly automate these processes and software has improved continually, making the machine ease of use and finished product design ever easier. However, the basic machining operations and the effect of a given tool on the type of material in a given workpiece remains the same. Lathe A sort of inverse drill, lathes spin the workpiece against a tool. A potter’s wheel spinning clay to fashion a uniform, cylindrical shape by the hands may be the earliest type of lathe.

More complex woodworking lathes have been discovered to be around 3,000 years old in Egypt and Greece. Wood turned artifacts that are over 2,000 years old have been discovered in Italy, Turkey, and China, and a painting from that era depicting a lathe was discovered in Egypt. The first lathes required two workers with one turning the workpiece with rope and the other shaping with a tool. It was essentially a potter’s wheel for woodworking. The Romans improved on this by adding a turning bow.

Spring pole lathes in later designs eased the wood work. A pedal, such as used with manual sewing machines, was used for rotating the work piece. These spring pole lathes would remain in use until the early decades of the 20th century. A drawing by Leonardo Da Vinci in the 1480s illustrates an early treadle wheel lathe. While also foot powered, a large flywheel provided momentum for more consistent turning of the workpiece. In 1772 a horse-powered boring machine was installed which was used for making canons.

During the Industrial Revolution, steam engines and water wheels were attached to lathes to turn at higher speeds, making the work faster and easier. Of course, powered tools were critical to the Industrial Revolution and the lathe stood central as it allowed development of other tools. Russian engineer Andrey Nartov invented a lathe with a mechanical cutting toolsupporting carriage and a set of gears in the early 1700s.

French inventor Jacques de Vaucanson made an allmetal slide rest lathe in the 1750s with his work documented in the Encyclopédie, the famed Systematic Dictionary of the Sciences, Arts, and Crafts. Dutch gun-founder Jan Verbruggen installed a horizontal boring machine that turned the workpiece was installed in the 1770s in the Royal Arsenal, Woolwich for cannon manufacture. Henry Maudslay became an artificer at the Royal Arsenal around this time.

His son, also named Henry, would invent the first practical screw cutting lathe, micrometer, and other key tools that would lead to the Industrial Revolution. Key inventions like this combined with mechanized power allowed faster and easier work. Metalworking lathes evolved into heavier machines with thicker, more rigid parts. Between the late 19th and mid-20th centuries, individual electric motors at each lathe replaced line shafting as the power source.

Beginning in the 1950s, servomechanisms were applied to the control of lathes and other machine tools via numerical control, which often was coupled with computers to yield computerized numerical control. Today, manually controlled and CNC lathes coexist in the manufacturing industries.

Mills Milling machines have also been a major influence in production and manufacturing, allowing countless innovations. The first modern incarnations were made to speed up filing with the earliest being built in the 1770s in France with a milling cutter being designed Jacques de Vaucanson shortly thereafter. Improvements would continue through the 1800s, with milling machine designs purpose-built toward production appearing in the middle of that century.

At first, they didn’t allow for the typical X, Y, and Zaxes of movement common today and were more like a drill press, In production use, several machines might be lined up, with each performing a single operation. Brown & Sharpe created their Universal Milling Machine allowing three axes movement in the 1860s. Improvements evolved, such as the jig borer for precisely locating hole centers, and the machines became more accurate.

Rudolph Bannow designed the Bridgeport milling machine in the 1930s, a 3 axis mill design still in use today. It was lighter, cheaper, and easier to use than comparable mills of the day. Bridgeport Machines, Inc. based in Bridgeport, Connecticut was founded soon after and manufactured milling machines until being bought out by Hardinge, Inc. in the early 2000s.

A standard manual knee-type vertical milling machine, Bannow’s design proved so influential that some people still refer to any manual mill as a "Bridgeport" and it is considered to be the original multipurpose mill. At the most basic level, a milling machine uses rotating cutters to remove material from a workpiece secured on the table by feeding it to the tooling. A variety of tooling is held in the spindle by a variety of collets and chucks. Along with the set speed, this is used based on the job being done.

With the tooling and speed set, the table fixturing securing the workpiece is moved along the available axis, controlled either manually by handwheels or by computer. A three-axis milling machine is the most common with tooling movement along each axis denoted as X, Y, and Z. By having a cutter that can move side to side, back and forth, and up and down, a machine should be able to cut a workpiece at any point on its surface.

Creating anew set-up by manually reorienting the workpiece on the table allows the cutting tool to access to any side of the workpiece. Depending on the hardware or software controlling a CNC mill, the cutting tool may not be able to move through all of the axes at once. For example, a three-axis machine denoted as "2.5D" or "2 + 1" indicates the mill can move through X, Y, and Zbut not at once.

Instead of performing a smooth curve in 3D space, the machine would have to stop its movement along one axis before moving in another. Some mills have more than three axes of movement, allowing for rotation around one or two of the X, Y, or Zaxes, taking account of position and orientation. In practical terms, these axes can be exploited by either rotating the cutting tool or tilting the table holding the workpiece.

A 4-axis and 5-axis machine can cut the workpiece from different angles than just the normal three and can complete the workpiece in a shorter time frame. This eliminates the need for multiple set-ups and complex fixtures, while greatly reducing the possibility of incorrect alignment, something that’s a risk every time the workpiece has to be reoriented. It also allows for more complex geometries and a smoother final finish.

A denotation of "3 + 2" milling is used to describe some five-axis machines, with the two rotary axes used to orient the part and tool angle, and then the three normal axes used for milling. A full five-axis machine. The head is mounted on the ram by joints that allow it to swivel in two directions. The ram can slide back and forth on the turret, which can swivel on the column. The table sits on the knee, and it can move horizontally in the Xand Yaxes.

The knee rides up and down the column (one form of Z-axis movement) and the head contains a quill in which the spindle can slide up and down, another form of Z-axis movement, or when the head is swiveled, an additional axis.

allows all five axes to be moved simultaneously. This requires more complex design as done with computer-aided manufacturing software but it saves time and provides a better finished surface due to less start-andstop motions. Drilling Gun drills, also know as Through Coolant Drills, are straight fluted drills which allow cutting fluid to be injected through the drill’s hollow body to the cutting face. They are used for deep drilling and a depthto-diameter ratio of 300:1 or more is possible.

While gun barrels are the obvious example of needing this kind of machining and the reason for the name, gun drills are also used in mold making, die making, and making engine parts such as crankcases Coolant is delivered through the center of the gun drill tool while a motor turns either the tool or the workpiece, or both. A feed system provides thrust to the tool to begin gun drilling The tool is guided accurately into the workpiece by a bushing.

While drilling, chips are flushed out along the gun drill flute by the force of high-pressure coolant. No peck drilling or interrupted feed is necessary to clear the chips. and cylinder heads. The coolant provides lubrication and cooling to the cutting edges and removes the swarf (chips) from the hole. Modern gun drills use carbide tips to prolong life and reduce total cost when compared with steel tips. Speed of drilling depends on the material being drilled, rotational speed, and the drill diameter.

A high speed drill can cut a hole in P20 steel at 30 inches per minute. Gun drilling can be done on several kinds of machine tools. On lathes, it is generally practical with hole depths of less than 50 diameters. There are also purpose-built gun drilling machines, where longer aspect ratios can be drilled. A typical gun drill consists of three parts: a carbide tip, a heat treated alloy shank, and a steel driver.

All are typically silver brazed together, and are designed to allow coolant to pass through its entire length. The shank must be properly formed, heat treated, and aligned to absorb cutting torque, sagging, and the whipping associated with high RPMs. Any size, feature, or length configuration can be optioned from 0.045" to 1.625" diameter. The drill is positioned and held in the spindle nose, then guided into the workpiece through a prestarted hole or guide bushing that prevents vibration and ensures accuracy.

Gun drill cutting edges form thin, curled chips that are carried away from the bore by high pressure lubricant. The off-center design of the cutting edges creates pressure within the bore that is carried by pads behind the drill tip. The coolant that flushes the chips also lubricates these pads, which burnish the surface and develop the fine finish for which deep hole gun drilling is known. The Future The most obvious, on-the-horizon next step in metal working is additive manufacture.

Better known as 3D printing, this process builds up apart layer-by-layer by placing material only where it’s needed. Additive manufacturing produces very little scrap or wasted raw materials, especially with very intricate designs. While mainstream recognition of AM didn’t begin until affordable desktop 3D plastic printers became available around 2010, the process is much older. (Continued on page 17)

The concept of 3D printing was described as early as 1945 in a short story by Murray Leinster, however, the first attempt at practical application wouldn’t happen until 1971 when Johannes Gottwald patented the Liquid Metal Recorder. Various other patents of the concept were filed through the 1980s with only a few attempts at production using hot-melt plastic. Laser sintering made the process more feasible for making metal parts.

Development of more powerful lasers in the 2000s allowed powdered metals to be fully melted, providing another leap for practical metal AM. Joule printing, a patented process by Digital Alloys, utilizes resistive heating of metal wire to form parts. Metal 3D printing remains out of reach for most of us. Entry-level machine costs can start around $50,000 and go up to a million or more. Powdered metal, currently the most common base material, has a starting cost of around $130 per pound, depending on the type.

However, the same used to be true of CNC machine options, which today can be had at prices affordable to gunsmithing shops. Like CNC, 3D printing will become increasingly more mainstream and affordable as will the design software for additive manufacture. Some industry experts predict additive manufacture will account for the majority of all manufacture within the next decade or so.

Even if this optimistic outlook proves true, it will be many years before AM replaces traditional metal working in most industries, especially in production. However, before then it may become more common for custom work. If the trend of improvement in technologies and price continue, gunsmiths working custom projects, especially those needing the replacement of unavailable parts, may print a one-off part based on a scan and reverse engineering in computer-aided design software included with the 3D printer. AG