Professional fabricators have a number of options available to create parts and products to specification and to also optimize the production process. Sometimes they must combine or build a complicated piece. The manufacturing process covers two primary categories: the removal process and deformation process. There are a variety of fabrication methods to produce the product.
The material removal process may consist of a variety of methods to remove some of the sheet metal material from the existing piece, including:
Cutting metal. The manual way of cutting metal with aviation snips continues to be one of the first tools fabricators use when working with metal fabrication. Power-scissors offer a way to cut metal more quickly and with less manual effort. Mechanical saw blades and laser beam technology are adequate for removing large amounts of material. A laser is especially effective on carbon steel, stainless steel and titanium, in addition to metals like aluminum and copper alloys that reflect light and conduct heat.
Machining. Fabricators remove material from a piece of sheet metal through machining – on a lathe, or by rotating the material against a cutting tool. Another option would be to use another cutting machine that has a rotating tool such as a drill. The number of axes in a machine defines the range of motion of the cutting head.
Punching. The punch-and-die tool operates similarly to a pair of scissors. The tool uses pressure to create a hole in the material and remove the slug or scrap. The punch produces holes and cut-outs of various shapes and sizes. The most common punched holes consist of geometric shapes like circles, squares and rectangles.
Blanking. This process removes a piece of material from the larger sheet and the desired part. Usually, fabricators blank multiple pieces in a single operation. Finished products range from jewelry to clock gears or watch components.
Stamping. This procedure works similar to punching, but instead of cutting, the die makes a raised portion of the material, without penetrating.
Shearing. The fabricator combines two tools to make a long cut on the sheet metal – one tool located above and one tool positioned below the sheet – to apply pressure to the material.
Nibbling. This process cuts a contour by creating multiple overlapping notches or slits in the metal, which allows the fabricator to form elaborate shapes. The punch comes in a variety of sizes and shapes, including oblong and rectangular punches, which minimize waste compared to a round punch.
When fabricators want to remove material without the need to create a deep hole, they use the milling process. The material removal stage constitutes the 2-D or shaping stage. The deformation process, such as bending or stretching creates a 3-D, complex shape.
The metal deformation or metal forming process utilizes applied force to a piece of sheet metal to alter its geometry rather than removing any materials. It alters the piece to achieve a certain design and includes:
Bending. Some sheet metal components require bending. Most fabricators use a brake press or press brake machine. This machine contains an upper tool called the punch and a lower tool called the die. It can operate manually or automatically. It consists of a set of dies that pinches the metal to form a crease. This operation has a limited number of uses because of the movement of the component and the possible configuration shape of the dies.
This method takes a flat sheet of sheet metal and bends or deforms the material to meet the intended design characteristics. A brake press along with the addition of manual computer numerical control (CNC) stops can specify the angle of the bend. The fabricator uses an overhead press, and a die set to both remove material and bend it in a single step.
Roll forming. This process shapes the sheet metal through a progressive series of bending operations as the sheet metal stock proceeds through a series of roll stations. As the machine forces the material through the roller dies, the metal deforms and bends. The process requires the use as a lubricant to minimize friction and reduce tool wear.
Spinning. Sometimes called spin forming, this metal fabrication method uses this process to fabricate cylindrical components by rotating a blank – a piece cut from the piece of sheet metal – while applying force to one side. This process produces a wide variety of products, including hubcaps, cookware, rocket nose cones, satellite dishes and musical instruments.
Deep drawing. Commonly used with ductile metals, such as aluminum, brass and copper, the deep drawing process stretches the sheet metal into the desired component shape. A tool places downward pressure on the sheet metal. The tensile force applied to the material causes it to deform into a cup-like shape. It is a common process to fabricate cans, cups, kitchen sinks, pots and pans fuel tanks, and automotive bodies.