Sheet Metal Fabrication

Because of the variety of products made from sheet metal, there are many fabrication processes used to create them. Sheet metal itself is rarely the final product; its fabrication is very important to many industries because of the diverse products it creates. Specifications such as part size, required strength, number of parts needed and additional materials are important factors for sheet metal fabrication. Whether done by hand or by a computer operated machine, sheet metal fabrication is a precise operation that seeks to reduce both the cost of materials and labor while creating a high quality part or product that will perform well for a long time. Practically every aspect of modern life whether residential, commercial or industrial, benefits from sheet metal fabrication. Sheet metal fabrication is a staple for many applications including the military, food processing and storage, communication, automotive, computer, medical, electronics, aerospace, pharmaceutical and construction industries.

Sheet metal is the metal formed into large, thin planes that are usually rectangular-shaped. Sheet metal is one of the fundamental forms used in metalworking, as it can be cut and turned into a variety of shapes and structures. Metal is made into sheet form by being heated into a malleable form and fed through a pair of rolls that compress the metal into thin sheets. Sheet metal suppliers are the first step in the transformation from raw material to finished part or product. They melt the metal into long slabs that are then compressed between large powerful rollers, resulting in large broad planes of metal. The sheet metal is usually shipped out to another plant for design and fabrication. Sheet metal design usually refers to a comprehensive plan regarding the part that includes the smallest details. The design helps ensure that the final product will be effective and safe by anticipating any potential problems, weak areas or stress points in the finished metal part. Sheet metal fabricators then use the design to manufacture the actual part. Sheet metal fabricating is the process of stretching and compressing metal materials into thin sheets; once compressed, the metal can be drawn, cut, punched or stretched. These processes are responsible for giving sheet metal a different shape, surface or size. Aluminum is one of the most common sheet metal materials because of its lightweight, tensile and compressive strength. Stainless steel sheet metal is one of the most important components to the manufacturing industry because the metal offers good corrosion resistance, strength and durability. It is also easy to clean and is therefore used frequently in harsh environments or around food.

Sheet metal forming is the process of stretching, compressing and shaping metal sheets. Sheet metal can be formed in many different ways. Stretching, for instance, is the process by which sheet metal is clamped around the edges and stretched to make various products. In contrast, drawing and deep drawing are stamping processes that makes flat sheet metal into various three dimensional forms. Cutting changes the size of the sheet and can also be used to cut the metal into shapes, whereas punches perforate the sheet and cut specific shapes out of the metal. Sheet metal work includes the various processes involved in heating and shaping metal sheets. Most metal working processes require heating the metal. Heating processes are used to harden or soften sheet metal by heating or cooling it until it reaches the desired level of hardness. Several important techniques may be used in the heat treating process, including annealing, quenching and tempering. Sheet metal bending typically produces a V-shape, C-shape or channel shape in the metal along a straight axis. Standard die sets are capable of bending the sheet metal into a wide variety of forms. All these processes result in sheet metal products. They are produced by sheet metal fabricators who weld, cut, perforate, spin, roll, stamp, bend, iron, draw, shear, saw, drill, blank, punch, deburr, sand and otherwise cut, form and finish sheet metal into the final product. Metal cabinets, pieces of industrial furniture used for storage purposes, are one example. Metal cabinets can be made out of a variety of different metal materials, including steel, aluminum and stainless steel.

Today's sheet metal fabrication processes may appear basic and in theory, they actually are. Using a punch and die system to bend a piece of material does not seem to be a complex action but when performed automatically by a machine hundreds of times a day is slightly more complicated, especially if the workpiece requires multiple bends along varying axes. Drilling a hole through metal is not a new practice; however, using a laser to cut through steel at precise depths and angles is a modern development. Large plants have automated lines that use robotics to move and turn sheet metal workpieces as they are formed, cut and finished. CNC (computer numeric controlled) machining is able to produce very accurate parts through use of software. The tools involved in sheet metal fabrication have also improved; saw blades are sharper, drills are faster and press brakes are stronger. Better tools provide better results because the operator is able to produce precise actions that can be repeated. A stronger press brake, for example, can bend the sheet metal into shape faster and with more force which decreases the stress from stretching. Less stress and stretching allow the metal to retain a uniform thickness without weak areas that would wear out faster.

Images Provided by Johnson Bros. Metal Forming Co.

Sheet Metal Fabrication Types

• Aluminum sheet metal is aluminum that has been rolled and pressed into broad thin planes.
• Annealing is a heating and cooling process used to soften metal. Annealing processes change the physical and mechanical characteristics of metal in order to create a specific microstructure.
  
• Bending involves straining metal material by moving it about a linear axis on a neutral plane, typically from strip metal or flat sheets. Flow of metal occurs within the range of plasticity for the metal so the bent portion remains permanently set after the stress is removed.
  
• Cold forming processes involve all those that occur at room temperature, such as bending, rolling and drawing. Cold Forming Processes are generally done to increase the strength and hardness of the metal.
  
• Cold rolling is the process of shaping sheet metal through rollers by compression and squeezing. The degree of strain establishes the hardness, along with the other characteristics of the completed material.
  
• Drawing is a process of forming sheet metal into a cup-like shape by forcing the material into a die with a punch, which stretches the metal into shape. The shape of the drawn part can be rectangular, circular, etc. depending on the cross section.
  
• Forging is the process of forming a hot or cold metal into a different shape by hammering or pressing.
  
• Hot forming processes involve all those that use a high temperature to lower a metal's resistance to shape change, such as hot rolling and hot stretching.
  
• Mechanical working is any process that puts pressure on metal with hammers, rolls or presses for altering the shape or physical characteristics of the metal material.
  
• Metal cabinets are storage units made from various types of sheet metal.
  
• Piercing is the process of punching or shearing holes and slots in sheet material. Piercing is similar to blanking, except that the resulting piece from piercing is scrap and the resulting piece from blanking is useful.
  
• Press forming is any sheet metal forming process that uses a mechanical hydraulic press.
  
• Punching involves die shearing in sheet metal so that the resulting material is scrap.
  
• Roll forming is a metal forming method for creating long parts with a variety of cross sections. This process forms sheet metal by passing it through a series of powered contoured rolls.
  
• Shearing involves the separation of material from a blade that forces the material past another opposing blade.
  
• Sheet metal is a flat and usually rectangular-shaped metal used in the manufacturing of various metal products.
• Sheet metal bending is a manufacturing process that bends sheet metal along a straight axis. Thin flat sheets of metal are placed on a press brake or other specialized machine presses, held down and deformed by a descending punch. Bending typically produces a V-shape, C-shape or channel shape in the metal; standard die sets are capable of bending the sheet metal into a wide variety of forms. 
• Sheet metal design is the process of planning out a product or part that will be manufactured from thin flat pieces of metal. There are many considerations to be made besides the usual specifications of dimensions, material and general shape. Sheet metal design usually refers to a comprehensive plan regarding the part that includes the smallest details.
• Sheet metal fabricating is the process that uses large rollers to make the large sheets of metal commonly used in metalworking.
• Sheet metal fabricators use a variety of processes to form parts from metal that have been compressed and stretched until thin and workable. Fabricators may also work with previously manufactured sheet metal that is reusable. Because sheet metal itself is rarely the final product, sheet metal fabricators have a very important role for many industries.
• Sheet metal forming is the process of stretching, compressing, and shaping sheet metal into various products.
• Sheet metal products are parts manufactured from broad planes of flattened metal that have undergone forming, cutting and finishing processes until complete. They are produced by sheet metal fabricators who weld, cut, perforate, spin, roll, stamp, bend, iron, draw, shear, saw, drill, blank, punch, deburr, sand and otherwise form and finish sheet metal into the final product.
• Sheet metal suppliers provide fabricators and manufacturers with thin flexible sheets of metal. Suppliers manufacture sheet metal in long wide strips that are then cut to size in order to be shipped or transported to the next factory to be pressed into shape and worked further.
• Sheet metal work is the metalworking process that forms products from various types of sheet metal.
  
• Slitting is the cold forming process of cutting a sheet of metal into smaller pieces to meet specifications.
• Stainless steel sheet metal is alloyed steel that has been rolled flat and compressed down into broad thin planes. Stainless steel has good corrosion resistance and is readily formed and welded.
• Stamping is the procedure of impressing three dimensional designs, lettering or surface definitions through pressurized tools like presses or dies.  
  
• Welding is a procedure for permanently bonding two or more metal components by melting both materials. Two common methods for sheet metal are spot welding and seam welding.

Sheet Metal Fabrication Terms

Adhesive - A substance that bonds the inner and outer panels of metal.
 
Age Hardening - Heating a metal to a uniform heat and then rapidly cooling it with air or oil to harden it.
 
Alloying Element - A metallic element that is added to another metal to produce an alloy in order to increase properties, such as hardness, strength and corrosion resistance.
 
Bend Test - A test that is used to determine the ductility and malleability of various metals.
 
Blank - A piece of sheet metal that has been cut for further press operation.
 
Bloom - A semi-finished piece of metal that needs further processing.
 
Brazing - The process of joining solid metals together by using a fusible filler metal with a melting point below that of the base metal.
 
Burr - A leftover ridge on the edge of metal caused by cutting operations, such as trimming, slitting and shearing.
 
Cavitation - The rapid formation and depletion of air bubbles within a metal during the solid/liquid interface. Cavitation can cause permanent damage to the material.
 
Cladding - The application of a thin coat of stainless steel to another metal in order to increase corrosion resistance.
 
Corrosion - The gradual deterioration of metals caused by harsh chemical and environmental conditions.
 
Corrosion Rate - The speed at which corrosion occurs on a particular substance.
 
Creep - The slow strain on metals, caused by stress, that occurs over time.
 
Cup - A sheet metal part that is cylindrical or shell-shaped with one end closed.
 
Deburring - The process of smoothing the rough-cut edges of metal.
 
Descaling - A process that involves removing the oxide layer, which forms on metal after hot forming processes.
 
Ductility - The amount of deformation a metal can withstand before failure.
 
Embrittlement - The loss of malleability in a metal after a physical change or due to chemical treatment.
 
Fatigue - The state of a metal after repeated stress, leading to an eventual fracture.
 
Finish Form - Forming a panel metal shape into a completed product.
 
Flange - A projection from the edge or rim of a metal part, typically narrow and of uniform width for fastening.
 
Grinding - Removing parts of the metal by using abrasives.
 
Oxidation - Corrosion of a metal due to oxygen.
 
Pitting - Localized corrosion on a metal surface.
 
Plastic Deformation - The application of stresses, which strain a metal material past its elastic boundary, resulting in a permanent distortion.
 
Plasticity - The capability of metal to undergo permanent deformation without breakage.
 
Strip - A very thin, flat-rolled metal product.
 
Yield Strength - Stress point beyond which a metal undergoes important permanent flow.