What Is Metal Fabrication? (Everything You Need To Know)

Metal manufacturing is one of the largest sectors of the industrial economy and it includes several subsectors. One of the most important subsectors is metal fabrication. If you’re interested in what metal fabrication is, whether as a hobby or as a career, it will be useful to understand what metal fabrication is and what the future of the industry looks like. 

So what is metal fabrication? Metal fabrication is the building of structures or machines out of standardized metal parts. Types of metal fabrication include cutting, bending, welding, and assembling. Metal fabricators turn metal into intermediate products or end products. Fabrication, as a subsector of manufacturing, is focused on preparation and assembly and less on building a product from the ground up.

Now as you probably know already, there is much more to metal fabrication and metalworking in general than what this article will talk about, but reading this is a good way to learn the fundamentals of this craft. This post will be useful for both experienced metalworkers and people just getting into this craft. I hope you find it useful!

Types of Fabrication Materials

The most commonly used materials in metal fabrication are standardized sections of sheet metal and structural steel. Examples of structural steel include formed metals like angle iron, tube stock, channels, H-beams, and I-beams.

Flat metals include thinner sheet metals, which are under 0.25 inches or 6mm, and plate metal, which is over 0.25 inches.

Sheet metal is made of steel, aluminum, or other alloys. It is used in heating or air-conditioning systems to make ducts but has many other applications like making rain gutters, signs, and siding (BLS). In addition to a regular plate or sheet metal, you can get expanded metal that has been cut and stretched out into something resembling a mesh.

Welding rod or welding wire is used to fuse metals with a filler metal. Welding wire comes in aluminum, carbon steel, copper-coated mild steel, and stainless steel. The flux-core wire used in flux core welding contains chemicals within it that acts as a shielding gas when activated. Arc welding uses electrodes either in a stick or wire form. Tungsten electrodes are used for TIG welding and can either be made of pure tungsten or include other chemicals.

The Fabrication Process

Fabricators put together finished products as well as make many of the parts that comprise them. Using hand tools, power tools, or larger machines, they make components for the automotive, aerospace, energy, construction, and defense industries. Specialists include welders, ironworkers, blacksmiths, boilermakers, and millwrights (bls.org).

Fabrication projects begin with a design plan which can involve drawings, blueprints, or schematics. The fabricator has to determine how they will connect the parts of the project using the necessary tools to cut, trim, shim, bend, or fold it so they can fit the pieces together.

Once everything is aligned properly, they fasten them together by welding, soldering, or brazing, or by connecting them with screws, bolts, or rivets (bls.org).

Metal fabrication projects can range from small household projects to making heavy equipment and machinery. For larger projects, metal fabrication shops, or fab shops, centralize multiple processes and multiple vendors that provide convenience to contractors by reducing the number of vendors they have to work with directly (Continelli, 2016).

Is there a Distinction between Fabrication and Machining?

There appears to be some confusion as to whether machining is a fabrication process, and there is a great deal of overlap in the capabilities of fabrication shops and machine shops. Fabrication shops tend to focus more on material preparation and assembly while machine shops focus more on manufacturing and finishing turning machines like lathes.

Metal-working processes like machining, metal stamping, forging, and casting are less common in fabrication, however, the North American Industry Classification System includes machine shops under fabricated metal product manufacturing subsector (bls.gov).

Millwrights install and maintain machinery and are closely related to machinists. Fabrication shops engage in machining processes like drilling, sawing, and shaping. Drill presses and milling machines remove the metal with a sharp cutting edge to achieve the desired shape.

Other processes typically associated with machining are boring, planing, broaching, reaming, and tapping. Machine shops produce turned products and fasteners like nuts, bolts, and screws, but many fabrication shops possess this capability as well.

Sheet metal fabrication

Fabrication sheet metal workers, precision sheet metal workers, or sheet metal mechanics produce sheet metal parts for industries from power generation to medical device manufacturing. Naval yards employ sheet metal mechanics to build lockers and ventilations systems for seagoing vessels. They’re also involved in forming the wings, fuselage, and ventilation systems for aircraft (bls.org).

While sheet metal mechanics still use hand tools, many large-scale fabrication shops have highly automated equipment where computers control processes like cutting, measuring, bending, and fastening.

Metal machine workers might handle limited computer programming for cutting or forming sheet metal. Products can be made using such systems as computer-aided drafting and design (CADD) or building information modeling (BIM) (bls.org).

Structural Metal Fabricators and Fitters

Structural metal fabricators and fitters are geared towards structural frameworks and work with larger, thicker sections of metal. They cut, align, and fit the parts and might weld or rivet the parts together as well.

Like sheet metal workers, they’re involved with the shipbuilding, defense, aerospace, and construction industries. Boilermakers from large containers and boilers, while ironworkers or steel erectors use materials produced in fab shops that are delivered to the worksite (bls.org).

How to Cut Metal: Tools and Techniques

Depending on the thickness of the metal, metal fabrication cutting techniques include sawing, shearing, chiseling, or torching. The tools can be hard-edge cutting tools, plasma cutters, laser cutters, abrasive cutters, and even water-jet cutters.

Shearing 

One of the most common ways of cutting sheet metal in fabrication is by shearing. Shearing, or die-cutting, use straight-edge blades to cut the metal with very little waste of the material. This process is more commonly used on thinner flat metals, like plate or sheet, to cut it to the appropriate size, but it can also be used on bars, angle stock, and tube stock.

Shearing encompasses a number of processes like punching, notching, roll slitting, and trimming. Blanking and piercing are produced by shearing. Blanks are the material punched out, while piercings are the resulting holes. A stamping press, when used to cut metal, is using a shearing process.

Roll slitting either involves log slitting or rewind slitting. In log slitting, a roll of sheet metal is cut while the roll rotates against the blade, resulting in a smaller roll being cut off from the “log.” In rewind slitting, the roll is unwound on one side, run through a cutter, and then rewound on the other side.

Punch presses are used to punch holes into the metal. These include single-station punch presses and turret punch presses as well as a combo laser and punch press. Fabricators also make holes using a variety of perforating and piercing machines, drills, and slotting machines.

Chiseling

Chiseling can be used in fabrication to cut metal. Cold chisels are made of tempered steel and used to cut metal without the aid of a heat source such as a torch. They are most frequently used when a highly smooth finish is not required or when other tools like a hacksaw or file cannot be easily used. As the name implies, a hot chisel is used while the metal is hot, most commonly in forging.

Circular Saws, Band Saws, and Abrasive Disks

Sawing involves hand saws, handheld power tools, or somewhat larger sawing machines like circular saws or band saws. Circular saw blades come in High-Speed Steel blades and tungsten carbide-tipped blades. Metal-cutting band saws come in both vertical and horizontal versions. Horizontal band saws are handy for cutting longer pieces of tubing or bar. Some band saws use fluids to keep the blade cool and lubricated.

Abrasive cut-off saws, or chop saws, use abrasive disks to cut metal. They come in tabletop and freehand form. Portable cut-off saws are often favored over torches for work done outside of fabrication shops. Compared to regular circular saw blades, abrasive cut-off disks generate more heat.

Plasma Cutters

The most common method used to cut thicker metals is with a plasma cutter. Plasma is a stream of ionized gas that can quickly and easily cut or trim metal to the desired shape. Plasma cutters are used to cut materials for structural applications.

Plasma cutters can also be used to break down large objects ranging from ships to automobiles so that the material can be repurposed. In fabrication shops, some employees operate plasma cutting machines (bls.org).

Cutting Torch

A cutting torch uses oxy-fuel to cut the metal. Oxy-fuel is also used for welding torches, and the main distinguishing feature between the two torches is the oxygen blast trigger on the back of the cutting torch.

The trigger is used once the metal has reached a cherry-red color to supply oxygen and increase the heat to the level that it will cut the metal. There are several oxy-fuels used for cutting torches but the most common is acetylene.

Numerical Control Cutters

Numerical control cutters or computer numerical control (CNC) cutters are automated machines. These machines use plasma cutters, milling cutters, burn table cutting torches, and even water-jet cutters to cut through the plate and larger pieces of metal. A water-jet cutter uses a high-velocity jet of water, sometimes mixed with an abrasive like sand, to cut the material. This is ideal when heating the metal would be a concern.

Bending and Folding Tools and Methods

Bending applies pressure to the material in order to form it without removing material and can be done with punches or dies. Bending can be used to shape plate or relatively long but slim sectional metals like tubes, rods, bars, and beams. This is done using a variety of tools like press brakes, tube benders, stamp presses, and manual or powered hammers. 

The Press Brake

The most common form of bending equipment in metal fabrication is the press brake. Press brakes hold sheet metal in place using clamps. While held in place, the metal is formed when the punch presses the metal down into the die underneath. Special press brakes called corner formers can be used to quickly form objects like pans or dishes.

Folders and Panel Benders

Both folders and panel benders operate on a similar principle and are used to form sheet metal. A folding machine uses an upward swinging beam that folds a clamped piece of sheet metal to the desired angle, or angles, as many times as necessary to achieve the desired form (Heston, 2018).

For panel benders, a sheet is placed underneath “blank-holder” tools that lower in order to clamp the sheet in place. Now secured and with the sheet metal sticking out on either side of the machine, the bending blades coming from both above and below form the piece of metal (Heston, 2018). 

Tube Benders

Tube benders include press benders, rotary draw benders, and roll benders. Press benders use a die in the shape of the desired bend. The die is pressed into the tube, which results in some deformation since the tube has no internal support.

Rotary draw benders use die sets and can be programmed for a variety of angles. The bend die clamps onto the tube and rotates to create the bend while the pressure die and wiper die to keep the rest of the tube straight.

Roll benders use three rollers to bend metal into circular shapes. Three-roll push benders use pressure rolls to guide the metal toward the bending die and the forming roll.

Simple three-roll benders are often in a vertical set up with one roll on top and two underneath. Some rolling machines include end formers that form the tube ends into a specific shape and can involve cutting.

Assembling Tools and Methods

One of the most important aspects of metal fabrication is the assembly process. Assembling can be done by welding, using adhesives, riveting, the use of threaded fasteners, or bending using a crimping tool.

Welding

The most common method of joining metal parts is welding. Welding uses heat to permanently fuse metal pieces together. Among the welding methods, arc welding is used the most today employing electrical currents to generate the necessary heat (bls.org). There are many forms of welding, but we will cover a few of the most common.

One of the earliest forms of welding, oxy-fuel welding uses a welding torch and gases such as acetylene. The torch is held over the base metal until a small molten metal puddle is formed. The welder moves the puddle along the path where the weld bead is needed. A metal rod can be used to add metal to the puddle and to move it along by dipping the rod into the puddle.

In contrast to oxy-fuel welding, arc welding uses electrodes in the form of rods or wires, sometimes with a coating called flux. The most popular of the arc welding methods is shielded metal arc welding (SMAW), more commonly called stick welding.

Stick welding uses a flux-coated electrode which produces a shielding gas to protect the weld. Flux-cored arc welding (FCAW) also uses a self-shielding electrode, but the electrode is a continuously fed wire. This allows FCAW to be one of the fastest welding methods.

Gas metal arc welding (GMAW) is one of the most common welding methods that use a shielding gas instead of a flux rod or wire. Gas flows through a hose to the nozzle accompanying the electrode as it contacts the metal. The gas prevents contaminants like hydrogen or oxygen from entering the weld and weakening it. MIG welding (metal inert gas welding) is the most common form of GMAW.

MIG welding uses primarily inert gases like argon or helium, sometimes with small mixtures of C02 or oxygen. Gas tungsten arc welding (GTAW), more commonly known as TIG welding, uses only inert gases like argon or helium as shielding gases.

After fitting the parts together, welders tack-weld the metal parts into place and then measure to make sure they’re still level and in place. Tack-welding is simply welding in a few spots to hold it together before doing the complete weld bead. A unit of welded pieces is known as a weldment.

Since welding using high levels of heat, there is a risk of overheating the metal and causing warping. Designers need to take this into consideration and may have to redesign products so that they require fewer welds or find a way to stagger the welds so that they are not opposite one another.

Sometimes weldments are covered in sand as they cool. Where warping has occurred in weldments, the welder can reheat the metal with a torch. By sweeping the torch over the steel in a slow, linear fashion, the steel will contract in the direction of the sweeping motion (Metal fabrication).

Soldering and Brazing

Soldering and brazing also use heat to join metals. The main difference between soldering and brazing is the heat required to melt the filler metal. The filler metal for soldering has a much lower melting point of 840°F, while brazing requires a higher melting point.

Both soldering and brazing use filler metal with a lower melting point than the piece being worked on. The advantage of these processes compared to welding is that they usually don’t cause weaknesses or distortions in the workpiece, which can happen with welding especially if done improperly (bls.org).

Fasteners

Metal fasteners include rivets, bolts, nuts, and screws which are either cast or stamped. Metal adhesives are used in conjunction with screws to help form a better bond. For rivets, orbital formers can be used to shape rivets that are sticking out. Crimping tools are used in applications like roofing where metal panels are crimped at overlapping sections to hold them in place.

Job Outlook

According to the Bureau of Labor Statistics, while overall the jobs of assemblers and fabricators are expected to decline by 11% specific areas are expected to experience growth:

Occupation	Average Annual Income	Number of Jobs	Percentage Increase/Decline
Metal and plastic machine workers	$36,080	1,073,900	-8%
Welders, cutters, solderers, and brazers	$41,380	424,700	3%
Machinery maintenance workers, mechanic, and millwrights	$51,630	506,900	5%
Boilermaker	$62,150	14,500	6%
Sheet metal workers	$48,460	143,000	8%
Ironworkers	$52,770	98,600	11%

The metal fabrication industry has shifted from fabrication shops that focus on only a few large projects to maintaining a higher volume of sales through diversification. The flexibility of such a strategy enables them to adapt to the cyclical nature of the metal fabrication industry and appeal to a wider array of customers through custom metal fabrication (Continelli, 2016).

Considering Fabrication

Metal fabrication involves the preparation and assembly of standardized metal parts to produce a finished product from materials like structural steel and sheet metal. Once the fabricator has decided how they will fit the pieces together, they with cut or form the metal before assembling it by welding or through fasteners. 

Metal fabrication is a vital element of our economy and, even with increased automation, the future holds prospects for growth for sheet metal workers and ironworkers in particular. Fabrication shops that remain flexible and able to shift production to sectors where demand is high should be able to thrive in the near future.

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Retrieved 20:00, December 6, 2019, from https://en.wikipedia.org/w/index.php?title=Metal_fabrication&oldid=926799055

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