UCI / Sheet Metal Properties

Properties:
Sheet metal's ability to be stamped or fabricated into various shapes and sized is determined by the materials used in its manufacture. However, these abilities (sheet metal properties) also determine the extent or limit to which sheet metal can be worked. The sheet metal properties directly affect is reparability once it has become damaged during product assembly. Because of this, these properties is known as the "yield point". This yield point relates to the amount of force that can be exerted on sheet metal without causing bending or deformation.

Metal Plasticity:
The ability of metals and materials to be formed when force is applied.

Plastic Deformation:

When flat sheet metal is drawn or stamped into desired shapes/parts, the plastic properties of the metal allow it to do so without the metal breaking or splitting. This is plastic deformation. Because of the degree to which the plastic deformation of sheet metal must achieve soft grades of metal must be used. Harder grades of metal do not have the plastic deformation ability to withstand the forces necessary in stamped part fabrication. The plastic deformation of metal by tension is called "stretching". In sheet metal repairs, both the stretching and upsetting of the metal surfaces are involved.

Work Hardening:
This is the plastic deformation of sheet metal without the application of heat during its drawing/stamping process. When flat sheet metal has been subjected to plastic deformation without heat application, the metal gains substantial stiffness and strength, or work hardening. Examples of the areas affected by work hardening are character lines, quarter panel edges, gas door openings, etc.

Elasticity:
This is the ability of sheet metal return or "spring back" to its original shape after pressure has been applied. All sheet metal has a limited point of elasticity. This limit point, as previously mentioned, is called the "yield Point". Even though the yield point has been reached, there is still enough metal elasticity to allow a partial ability for spring back. This ability for sheet metal to spring back should be taken advantage of during sheet metal repair, and repair personnel need to recognize the elastic strains on damaged sheet metal. Spring back is more readily visible in large flat sheet metal surfaces. An example of spring back is the return of a buckled body panel that has been welded off location to its original shape by cutting the welds holding it out of position.

Heat:
This obviously refers to the high temperature achieved when sheet metal is subjected to the usage of torches, welding, or by the friction created by stamping, grinding or sanding. The effects on the sheet metal can be varied. The heating of sheet metal causes its molecules to expand, there by increasing its flexibility. Excessive heat can cause severe buckling and warping.

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