What is Metal Forming
When using a certain amount of pressure, metal bends and returns to its original shape with what's called elastic deformation. In elastic deformation, a material compresses, stretches or bends in an amount directly proportional to the amount of force being applied.
The different types of metal forming use a higher level of pressure on the metal to create a more permanent change in the shape. When enough pressure is applied, metal undergoes plastic deformation, which is a geometric change in the material that is no longer directly proportional to the stress. Thus, changes in shape remain after the pressure is released and the metal will not return to its original shape.
Metal Forming Processes
All metal forming processes involve the use of various tools, such as a die and punch, to compress and shape a piece of metal. Depending on the type of metal forming, these tools will be shaped and used differently. Temperature also affects how the metal is deformed during each process. Cold, warm and hot working all have different benefits and pitfalls, but depending on the form you need the metal to take we'll choose the best process. Bulk forming of metal is a severe deformation process that results in a massive shape change. The different types of bulk forming include:
· Rolling - The thickness of a slab or plate of metal is reduced using rolls
· Forging - Two dies that contain shaped contours compress the metal to change its shape
· Extrusion - The metal is pushed through a die opening and forced through the other side to take the shape of the cross section
· Drawing - The metal is forced through a die opening: however, it is pulled rather than pushed
Sheet forming involves forming metal sheets, strips and coils into new shapes. The different processes for sheet forming include:
· Shearing - The process of cutting a sheet of metal; it doesn't use plastic deformation but is a critical process
· Bending - Using a punch and a die, metal is deformed on a certain axis
· Deep drawing - A flat piece of sheet metal is forced into a die opening to take a shape, such as a cup