Sheet Metal Guide
Basics
Sheet metal is a thin, flat piece of metal formed by industrial processes. It is a fundamental form of metal used in metalworking, which can be cut and bent into various shapes using a bending machine.
Figure 1. Bending Sheet Metal with a Hydraulic Bending Machine
Sheet metal comesin different thickness up to 0.25 inches. Anything thicker than that is referred to as a metal plate or structural steel. Ideally, sheet metal should have the following attributes:
1. Easy to shape
2. Strong enough to undergo forming under pressure
3. Decent malleability
Metals that match the above attributes include iron, steel, stainless steel, copper, aluminum, etc, all of which are common metals used to make sheet metal. You may even come across silver and gold metal sheets, but they are mostly for decorative use.
Fabrication
The vast use of sheet metal is beyond imaginable. Let’s take a look at some of the industrial processes where it is processed as a raw material:
● Bending
Bending a piece of metal sheet can be as easy as using a vise and a mallet, but should be done with extreme caution and care. Alternatively, a hydraulic bending machine may be used in conjunction with a V-shaped groove to bend it that is considerably thicker.
● Curling
Curing is a technique that is used to remove the sharp edges on sheet metal. This process can cause considerable wear to the tool over time, so tools made out of steel are typically used to curl the material.
● Decambering
Decambering is the metalworking process for removing horizontal bend from strip shaped materials. Through this process, the sheet metal becomes flat and leveled. It is possible to deform the edges if not performed properly.
● Deep Drawing
This process involves stretching a piece of metal sheet over a die. It is typically used to manufacture automotive parts, aluminum cans, etc. Parts being deep drawn are sometimes heated in advance to prevent tearing.
● Hemming and Seaming
Hemming means folding a piece of metal sheet onto itself to create a more rigid edge. Seaming involves folding multiple pieces of metal sheets to form a thicker and stronger sheet metal.
● Hydroforming
This process is very similar to deep drawing. It utilizes very high hydrostatic pressure to generate enough force to shape the sheet metal. During hydroforming, it the sheet metal is also stretched across a module or die.
● Ironing
Ironing is a useful forming process that utilizes heat to form the sheet metal. It can produce a part with uniform wall thickness by thinning it in a specific area.
● Press Brake Forming
This process uses a press brake to produce long, thin sheet metal parts. The upper part of the press brake punches downward against the V-shaped groove located at the bottom, bending the metal sheet into an acute angle.
● Punching
This process involves placing the sheet metal between a punch and a die mounted in a press. And the press pushes the punches against the die until the sheetsheet metal is completely pressed into the die, forming the desired shape.
● Rolling
The primary purpose of rolling is to ensure uniform thickness throughout the entire metal sheet. Depending on the thickness requirement, either hot rolling, cold rolling, or warm rolling is used.
● Spinning
This process is used to produce tubular parts by fitting a piece of metal sheet into a mandrel. It is used to make missile nose cones, rocket motor casting, and kitchen funnels.
● Stamping
Stamping is a combination of operations including punching, blanking, embossing, bending, and flanging to form the sheet metal into complex shapes.
● Wheeling
It is a forming technique that uses a wheeling machine to make a curve shape out of a piece of metal sheet.
Typical Products
Below are some of the common products that are made from sheet metal:
● Parts of Transportations
Sheet metal is used to make all kinds of vehicle and aircraft parts, such as fuselages and wings of airplanes, components of trucks and ships.
● Decoration
Sheet metal is often used as a material for roofs or decoration for building andis especially popular among artisans in decorative applications.
● Cans
In food processing industries, stainless steel and aluminum sheets are often used to make cans.
● Medical Equipment and Instruments
Stainless steel sheet, which is highly resistant to wear, is ideal for the production of medical equipment and supplies.
● Military
Military equipment needs to be made with the utmost of rigidity. Therefore, stronger and thicker sheet metal is often used to make body armors and parts of firearms.
Aluminum or Stainless Steel?
In this section, we discuss when you should choose stainless steel sheet or aluminum sheet.
Stainless Steel
Stainless steel sheet features excellent corrosion resistance and weldability. For applications that require maximum resistance to corrosion, such as pumps and valves, consider grade 316 stainless steel sheets. For stainless steel sheets that are heat treatable, grade 410 stainless steel is the best choice. It is often used in cutlery. Finally, grade 430 stainless steel sheet is perhaps the most popular and economical option of all, but should only be used when corrosion resistance is not the primary concern. It is commonly used in appliance products.
Aluminum
Aluminum sheet is characterized by its flexibility, versatility, and cost effectiveness. For deep drawing applications, grade 1100-H14 is the ideal choice because of its superior weldability. For applications that require strong and corrosion resistant, grade 3003-H14 aluminum sheet is the way to go. It is commonly used to make mail boxes, cabinets, tanks, and fan blades. Grade 5052-H3 aluminum sheet not only is stronger than the above, but also maintains decent formability at low cost. Finally, for aluminum sheet that can be heat treated, grade 6061-T6 is the best choice, as it is often used to make aircraft parts.
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