Sheet Metal Fabrication
Sheet Metal Fabrication consists of any of a variety of processes that are used to convert a raw piece of sheet metal into a specific shape, configuration or assembly. This can happen through cutting specific features into the part, bending or forming it into different shapes, or connecting multiple pieces together. Sheet metal itself can come in a variety of materials, but most common are aluminum, carbon steel or stainless steel. These sheets often come in thicknesses ranging from .006” to .250”.
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Sheet Metal Forming
Because of the thin and therefore flexible nature of sheet metal, it can undergo a variety of different processes to bend and reshape the material that thicker metal plates cannot endure. Sheet metal forming, or what is often referred to as sheet metal bending, covers any techniques used to apply an outside force to the surface of the sheet to modify the shape. In this case no material is actually removed.
Perhaps the most common type of sheet metal forming equipment is that of a press brake to perform a process called bending. As the name implies a press brake is a powered press, that is driven by either hydraulic, pneumatic, servo-electric, or mechanical power transmission. These units can be outfitted with a variety of dies to create different bend angles, radii, and unique shapes in the sheet metal. These presses are often automated so that the exact force output and geometric features can be highly controlled and very repeatable. Typically these presses have significant output force (can be in hundreds of tons) and are therefore able to bend thicker material and create more complex shapes.
Curling is another sheet metal forming technique that is used to bend over the edge of a sheet metal piece to hide any sharp edges caused when cutting or shearing the metal. This process uses a specific type of die on a press that comes in contact with the edge and produces a radius and continues to ‘curl’ that radius around until the edge tucks back in on itself, hiding any sharp edges.
Other forming techniques exist that have their place in specific applications. Ironing is one example, where the metal is pressed between two flat surfaces in order to thin out the material. Hydroforming and Deep Drawing are other techniques where the sheet is reshaped either through hydraulic pressure or mechanical force to conform to a die. Unlike with a press brake where typically one feature is created at a time (eg- think of bending to a 45 degree angle) in a hydroforming or deep drawing application, multiple features are formed in the sheet at the same time (eg- think of a car hood with multiple curves, cavities, etc).
Sheet Metal Punching
In sheet metal punching, a punch and die set are used to remove material from the sheet. Again a powered press (typically hydraulic or servo) is used to stamp out desired shapes in the part. With this technique a hardened punch tool (typically hardened steel or carbide) is used to press through the sheet metal and into a die set that sits on the opposite side of the punch. For example if you want a ½” diameter hole, you would use a ½” diameter punch that fits into a ½” diameter hole in a die (neglecting tolerances). The punch sits above the die and when the sheet metal is slid in between, the punch comes down, stamps out the hole and the scrap piece that comes out falls into the die.
This process is a relatively quick and repeatable process, and is much less costly than machining these types of features in sheet metal.
Sheet Metal Cutting
There are a variety of techniques used to cut sheet metal. Shearing is a process using a press with blades that sit above and below the material. When the blades come together they shear the piece. Shearing is best for straight-line cuts (picture a paper shear). Sheet metal can also be cut using manual tools like a handheld shear or a sheet metal nibbler tool. Both tools work similarly in that you run them along the surface of sheet metal and they take small cuts away at high speeds allowing you to maneuver along a path (imagine how a pair of scissors work on paper). Other, more automated techniques for cutting sheet metal include laser cutting and water jet cutting. These allow for more complex shapes. Both of these techniques are explained in more detail in the Metal Cutting section of this site.
Due to the thin nature of sheet metal, it is not always an optimal material to thread directly into. This is because the thread depth and/or material properties are often not sufficient enough to meet required holding strength for a connection. In this case a common solution is to make use of threaded inserts. A threaded insert (commonly referred to by the industry standard brand name- PEM) is a threaded stud that can be hard mounted to sheet metal and provide a stronger, reusable and permanent threaded solution. There are a variety of stud designs that can be used to provide different connection types and different ways to attach the insert into the sheet metal, but the most common design functions by inserting the stud into a looser fitting hole and then squeezing the stud, which deforms the material and creates a flanged surface on the underside of the stud, preventing it from moving laterally. Commonly this is a machine operated installation process, through the use of a custom machine designed to load, insert and attach the threaded insert.
Our Metal Fabrication Process and Approach
Sheet metal applications are common work for us at KPI. We have a variety of in house capability and broadly supplement that with a strong group of partners that we work closely with to meet a wide range of sheet metal fabrication needs. Whether you have a need for a small volume of simple parts to high volume or highly complex integrated solutions, we can support your needs.
We can support a variety of materials, from steel to stainless steel to aluminum and more. We cover industries from medical, to energy to defense to instrumentation and robotics and more. Have a current or upcoming project? Have a member of our team contact you to discuss.
Metal Fabrication Applications
There are a wide variety of uses for fabricated sheet metal parts, and the list is too extensive to cover here. Some common example applications that we often see are shown below-
- Skins/covers for machines or guards
- Enclosures- electrical panels
- Brackets for assembly of multiple components together
- Chassis for electromechanical controls
- Automotive- outer panels on cars/trucks
The Advantages of Metal Fabrication
There are numerous advantages associated with the use of sheet metal for specific applications. As compared to thicker metal plates, the strength to weight ratio of sheet metal is very good. This means that they are easier and less costly to transport and when used as part of a larger piece of equipment, keep the overall system weight down. When properly constructed the strength of sheet metal fabrications is undeniable and often more than sufficient to handle structural requirements. Sheet metal is also a very cost-effective solution relative to other common options. Sheet metal is relatively easy and low cost to modify and to fabricate, keeping overall cost down.