What is Sheet Metal?
Sheet metal is metal formed by an industrial process into thin, flat pieces. Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes. Countless everyday objects are fabricated from sheet metal.
Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate steel or “structural steel”.
Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll slitter.
In most of the world, sheet metal thickness is consistently specified in millimeters. In the U.S., the thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge. The larger the gauge number, the thinner the metal.
Commonly used steel sheet metal ranges from 30 gauge to about 7 gauge. Gauge differs between ferrous (iron-based) metals and nonferrous metals such as aluminum or copper. Copper thickness, for example, is measured in ounces, representing the weight of copper contained in an area of one square foot. Parts manufactured from sheet metal must maintain a uniform thickness for ideal results.
Types of Sheet Metal
There are many different metals that can be made into sheet metal, such as aluminum, brass, copper, steel, tin, nickel, and titanium. For decorative uses, some important sheet metals include silver, gold, and platinum.
Due to its numerous benefits including its abundant supply, low cost, ease of fabrication, good strength-to-weight ratio, high electrical and thermal conductivity, corrosion resistance, non-toxicity, and high recyclability aluminum finds application in a variety of sheet metal fabrication operations.
Some of the typical for which aluminum sheets are used include automotive parts, electrical devices, and cooking vessels.
2. Aluminized steel
Aluminized steel is made by coating carbon steel with an aluminum-silicon alloy. This process results in a material that combines the high strength of carbon steel with aluminum’s superior corrosion resistance. Sheets of aluminized steel are used for products intended for high-temperature or corrosive environments, such as cooking implements and kitchen appliances.
3. Carbon steel
Carbon steel is a steel alloy that contains carbon (up to 2.1%). As the carbon content increases, the resultant material increases in hardness and strength when it undergoes heat treatment operations and decreases in ductility. Carbon steel is used for many products in the industrial and consumer markets.
With lower zinc content brasses can be easily cold worked, welded, and brazed. A high copper content allows the metal to form a protective oxide layer (patina) on its surface that protects it from further corrosion. This patina creates an often highly desirable aesthetic look found in architectural or other consumer-facing products.
Compared to aluminum, copper features higher electrical and thermal conductivity. However, it is also more expensive. Typical products made from copper include heat sinks, roofs, rain gutters, and doors.
5. Galvanized steel
Galvanization is the process of applying a protective zinc coating to steel in order to prevent rust and corrosion. Annealing is a heat treatment process that alters the microstructure of a material to change its mechanical or electrical properties, typically reducing the hardness and increasing the ductility for easier fabrication.
Sheets of galvanized steel are used for making automobile bodies, water pipes, and many construction elements like fences, roofs, and staircases.
When steel is galvanized by an alloy of aluminum, zinc, and traces of silicon, it is called galvalume. The resultant material is more durable and corrosion-resistant than galvanized steel. Due to the material’s superior corrosion resistance, galvalume sheets are used for outdoor applications, such as on roofs that are regularly exposed to weather elements.
7. High strength steel
Military armor plates are made from sheets of high-strength steel. The material is made by alloying steel with a variety of elements like carbon, manganese, and copper to improve its hardness.
8. Hot rolled steel
Compared to cold rolled steel, hot rolled steel is much cheaper to manufacture. It is commonly used in structural applications, such as in automotive body parts.
9. Stainless steel
Stainless steel is a steel alloy with at least 11% chromium content and less than 1.2% carbon by weight. The material offers superior corrosion resistance, fire and heat resistance, strength-to-weight ratio, and manufacturability. Kitchen vessels, storage tanks for chemicals, and parts for food processing machinery are some of the common applications of stainless steel sheet metal.
There are a number of grades to choose from, for the purpose of this white paper we will focus on the top three found in precision sheet metal fabrication:
- Austenitic stainless is a non-magnetic: Any of the 300 series steel – that contains high levels of chromium and nickel and low levels of carbon. Known for their formability and resistance to corrosion, these are the most widely used grade of stainless steel.
- Ferritic: Stainless steels that are magnetic, non-heat-treatable steels that contain 11-30% chromium but with little or no nickel. Typically employed for non-structural uses where either good corrosion resistance is needed such as with seawater applications or decorative applications where aesthetics is the main concern. These metals are most commonly found in the 400 series stainless steel.
- Martensitic: A group of chromium steels ordinarily containing no nickel developed to provide steel grades that are both corrosion resistant and hard enable via heat-treating to a wide range of hardness and strength levels.
Titanium has several advantageous metallurgical characteristics that make it suitable for a wide range of industrial applications. Although it is primarily used for its high strength-to-weight ratio and corrosion resistance, it also offers high recyclability, durability, and biocompatibility. Typical uses include aviation parts, medical equipment, and construction elements.
Uses of Sheet Metal
Sheet metal is used in automobile and truck (lorry) bodies, airplane fuselages and wings, medical tables, roofs for buildings (architecture), and many other applications.
Sheet metal of iron and other materials with high magnetic permeability, also known as laminated steel cores, has applications in transformers and electric machines.
Historically, an important use of sheet metal was in plate armor worn by cavalry, and sheet metal continues to have many decorative uses, including in horse tack.
Sheet metal workers are also known as “tin bashers” (or “tin knockers”), a name derived from the hammering of panel seams when installing tin roofs.