Sheet metal is used widely in a variety of industries, including consumer electronics, aerospace, and other sectors. The sheet metal cutting process is a particularly important part of fabricating sheets of metal into components of a wide array of consumer and industrial products. Used to remove unneeded material, shearing involves the use of machines or tools to precisely cut sheet metal. Cutting processes like shearing neither require heat nor produce waste, which makes the shearing process for sheet metal particularly attractive to manufacturers.
Shearing is the same action that occurs in earthquakes as tectonic plates move against each other. It refers to the specific method by which metal is cut, though this happens on a much smaller scale. Stress caused by two opposing external forces that push against each other enables the corresponding inner surfaces of the sheets to slide past each other as they separate during the shearing process. In sheet metal fabrication, shearing is one of the most widely used methods for cutting metals.
The Shearing Process in Sheet Metal Fabrication
While there are a number of other methods that use sheer force to cut through sheet metal, the term “shearing” usually refers to a specific sheet metal cutting process. This method for cutting metal generates very exact edges, separating the sheets neatly. Most commonly used to cut sheets held square to an existing edge, this sheet metal cutting process can also be used to make angular cuts.
Advantages of Shearing
Shearing typically is part of a bigger fabrication process, used to cut sheets into smaller sizes for use in the assembly of other products.
The shearing process in sheet metal production has the following advantages:
- Able to cut through varying diameters of sheet metal easily.
- Cost-effective means for cutting metal, especially when used in high-capacity operations.
- Produces clean, smooth-edged cuts.
- Produces no metal chips and is a virtually waste-free sheet metal cutting process.
- Quickly cuts through sheet metal in seconds.
- Requires no heating and can be done at room temperature.
- Versatile technique for sheet metal cutting, able to shear through metals that include aluminum, bronze, copper, iron, steel, and stainless steel.
There are a few disadvantages when using a shearing process in sheet metal, however. The process is less than ideal for lower volume production runs, and very hard metals – such as tungsten – cannot be cut using the shearing process. In sheet metal, it also sometimes deforms the sheets when blades are damaged or dull, because of improperly placed shear gaps or due to applying too much or too little pressure when being held down.
Another very similar sheet metal cutting process is known as die-cutting. The primary difference between shearing and die cutting involves the different types of cutting blades each sheet metal cutting process employs. While die cutting uses curved blades, shearing uses straight blades instead. Otherwise, both methods for cutting sheet metal produce straight lines to process metal sheeting with little to no waste.
Equipment Used for Sheet Metal Cutting Process
There are a number of ways to accurately achieve a smooth finish using the shearing process. In sheet metal production, many different types of machinery can perform shearing operations. Though certain machines or tools can operate manually, others use hydraulic, pneumatic, or electrical machinery. Standard shearing machines often include a table that features arms to support and guides to secure the sheet metal, along with straight-edged blades positioned above and beneath the sheets.
The sheet metal cutting process involves placing the sheet between these two blades, which are then forced together to cut the metal. With most shearing machines or implements, the lower blade is stationary while the upper blade applies a downward force on the metal sheet. Often, the upper blade is angled to ensure the force required continually lessens as the cut moves from one side to the other. For the shearing process in sheet metal, a number of different pieces of equipment can be used.
Alligator Shears
Using a hinged jaw, as per their namesake, alligator shears are used in a wide range of metal cutting operations. Powered via hydraulics, they typically are only used for cutting through smaller pieces of sheet metal.
Bench-Mounted Shears
Bench-mounted shears use a compound implement, which offers a better mechanical advantage. They are ideal for cutting medium-sized sheet metal workpieces into approximate shapes. Bench shears are versatile, able to make multiple types of cuts. These machines also come in various sizes with varying strengths and can produce clean, burr-free cuts.
Metal Guillotines
These are made up of lower and upper shears, a shear table, a device for holding the workpiece and a gauging mechanism. Metal guillotines are powered mechanically, hydraulically or manually via foot power. They work by holding the metal sheet with a ram and moving the metal blade down until it crosses a fixed blade, which cuts the metal. To reduce how much force is needed when cutting large pieces of metal, the moving blade can either be straight or set at an angle.
The sheet metal cutting process with guillotines offers both speed and economy to the shearing process. In sheet metal manufacturing, the machine is ideal for high-capacity assembly lines. As they tend to produce rougher edges than other implements used during the shearing process, in sheet metal production they are normally used to fabricate components where aesthetics are not important, or if they are to be welded later.
Power Shears
These shears are ideal for making blanks from large pieces of sheet metal. Cutting processes with power shears utilize electricity or pneumatics to run the machine, though the machine is operated by hand. The upper blade moves towards the lower blade, which stays in a fixed position and exerts tension to cut the sheet metal. Generally used for cutting straight lines or curves with larger radiuses, power shears offer flexibility, accuracy, durability, and efficiency.
Snips
Snips are hand tools designed specifically for the sheet metal shearing process. In sheet metal cutting processes, two general types of snips are used, compound action and tinner snips. The compound action snip offers a greater mechanical advantage due to a featured linkage and comes in several different varieties. These snips are used for stainless steel, mild steel or aluminum.
Tinner snips feature short blades with long handles, used commonly for cutting mild steel or tin with low carbon content. Tinner snips also come in different varieties. Used for their precision, they are primarily for more delicate sheet metal cutting processes. However, because they are operated by hand, cutting with snips is time-consuming.
Throatless Shears
Throatless shears are designed for making intricately curvy, irregular or straight cuts. Unlike many other shearing machines, throatless shears allow the workpiece to move freely.
Industries & Products That Use the Sheet Metal Cutting Process
Sheet metal cutting processes are used in many different industries. Generally, the production of sheet metal falls into three types.
These categories are:
Commercial sheet metal production involves making consumer goods, such as automobile bodies, appliances, vehicle hoods, caps, cans, mailboxes, cabinets, cutlery, and consumer electronics.
Industrial sheet metal production involves fabricating components used in other products, many of which are used to manufacture consumer products; industrial fabrication also involves making various implements like bandsaws, drill presses, hydraulic systems, and the like.
Structural sheet metal production involves the manufacture of components for construction, including structural framing studs for skyscrapers, ventilation systems, guardrails, brackets, gutters elevators, pipes, doors, metal siding, and roofing material.
Fabricating and shaping sheet metal is essential to the fabrication of a wide array of mass-produced items, and one of the more important elements of this practice involves shearing. In fact, sheet metal makes restaurants, food and beverage, farming, electronics, automobile, and many other industries possible.
To learn more about our sheet metal cutting capabilities, please contact us at Atlantic Stainless today!
