Metal forming – the art of non-destructive production
A metal has two limitations which are intrinsic to how it can be processed: yield and tensile strengths.
A metal will resort to its original form up to a specific level of force. This force is the "yield strength". It provides information about the metal's elasticity for the forming processes.
If the metal is subjected to forces beyond the yield strength, it will begin to deform. The range of deformation is referred to as the tensile strength. This provides the information required to form metal components. If the metal is stressed to the point of tearing, its tensile strength has been exceeded.
Forming methods include pressing, bending, stamping, bulging, stretching and deep drawing. The metal's mass remains the same whatever method is applied. Depending on the requirements, forming permits a wide range of possibilities. Large-scale forming is achieved through hydroforming and deep drawing.
Deep drawing is the cold forming of sheet metal through compression. A punch is driven in a linear motion into a die. The metal deforms and is pressed into the die. The resulting form from deep drawing undergoes extensive change and can be used for dimensions not possible using other methods.
The finished product is indistinguishable from the original sheet metal. Under the right conditions, deep drawing is a fast, efficient tried and tested method for producing large series of identically formed products. But it requires very fine tuning: the choice of metal and machine as well as the design of the tool must match each other precisely. This requires skill and experience. Not every metal is suited to this method.
A disadvantage of deep drawing is that forming takes place only in a linear direction. The punch is incapable of changing direction during the procedure. Deep drawn products are therefore always cylindrical or rectangular. Hydroforming is therefore available to produce any type of form from sheet metal. The main difference to deep drawing is the use of highly pressurized water in place of a punch.
A blank form is used in hydroforming. The tool comprises fixing points for the primary material, and cavities into which the sheet is to be drawn. After sealing the machine, highly pressurized water is injected onto the blank. The pressure is equally dispersed and the sheet metal forms perfectly to the interior sides. The metal is precision formed according to the requirements and is then removed from the machine.
The only disadvantage in hydroforming is its slightly slower rate of production. The tools are however much less expensive to produce and have much lower wear properties than conventional deep drawing.
Metal forming is an art. Hydroforming is the ideal companion to deep drawing. We offer our customers the expertise to provide alternative options in our production processes.