Sheet metal is an incredibly versatile material, and as such there are many different methods that can be used during sheet metal fabrication, especially for cutting the metal. Different cuts are used depending on the reason for cutting, what is being cut, and how thick the metal being cut is.
In sheet metal fabrication, cutting the metal occurs during many steps of fabrication, so it appears throughout the entire process.
1. Shearing
Shearing is probably the most basic type of cutting sheet metal during fabrication. It is frequently used to separate the sheet metal from the larger sheet or roll. It is not meant to create any detail, just to separate a piece of sheet metal into two so that it can be more easily managed and be further processed into the desired shapes.
Shearing uses force and a shearing blade to separate the metal into two pieces.
2. Blanking
Blanking is a method of cutting in which force and blades are used to push out a usable piece of metal from a larger piece of metal. So, the machine would push out the desired shape from a larger piece of metal, and all the surrounding metal would then become scrap. The blank, the piece that was pushed out, can then be further processed into the desired shape needed for the item being built.
3. Punching
Punching is exactly the opposite as blanking, it is a method where a hole is punched into a piece of metal. The piece that is punched out is scrap metal, and the larger piece of metal with a hole or multiple holes in it is the usable part that can then be further processed into whatever is being built.
There are multiple types of punching, each describes a different type of hole that can be made in the metal.
4. Piercing
Piercing is one of the types of punching. It is one of the most basic punching methods used. In piercing, a circular shape of a predetermined size is punched out of the larger metal piece. The punched-out piece becomes scrap. Often, when using piercing in sheet metal fabrication, the exact same machine and method is used as in blanking, except the user just switches out which piece becomes scrap metal.
Piercing is sometimes used as a general word synonymous with punching, however sometimes, as described above, it indicates only the punching out of circular shapes.
5. Slotting
Slotting is another method of punching. Similar to piercing the punching method is used to knock out a shape, however unlike in piercing, the shape that is punched out is a rectangle instead of a circle. This method is sometimes referred to as piercing as well.
6. Lancing and slitting
Lancing is a method which just creates a half cut where the piece is actually still attached to the rest of the piece. This type of cutting sheet metal during fabrication is good for pieces that need vents or louvers. To best describe lancing, it would be cutting three sides of a rectangle, specifically one long side and the two short sides, and then leaving the second long side attached.
Slitting is very similar to lancing, however it is just creating slits in the metal, straight or curved lines cut into the metal that are not a part of any real shape.
Neither of these methods create any scrap metal, as nothing is being punched out of the original piece.
7. Trimming
This method is simply just a matter of removing excess material from any part that has been created. This is a significantly more detailed type of cutting that occurs later in the whole sheet metal fabrication process.
