Surface defects

Especially for visible parts, it is important that the finished component is free of surface defects. With the solid simulation, in which the sheet metal is dissolved over the entire thickness, surface problems are realistically represented. The following can be recognized particularly well:

  • Local distortion of the surface
  • Skid lines on the final part
  • Roughened surface, the so-called orange skin
  • Markings from the tool contact


Orange skin:

A bended sheet is stretched on the outside and compressed on the inside. If the expansion gradient along the thickness is too large, very slight cracks appear on the outside, the so-called orange skin. If the part is bent further, this becomes a bending failure. An orange skin is clearly visible on the final part and if you run your finger over it, you can feel the damage very clearly. In the solid simulation, the orange skin is displayed as a failure just in the very surface of the sheet.


Tool marks:

Friction with the tool during forming often results in protruding areas that are particularly smooth. These spots are often caused by the fact that the sheet metal thickens locally during the forming process and when the press closes these spots are pressed together very strongly. At these points, the impressions then remain visible on the component. Since the solid simulation shows the thickening and compression in great detail, the marks are particularly visible here.


Distortion of the surface:

When a tool with a very narrow radius hits a sheet metal part, material is displaced locally and a local distortion of the surface of the sheet is formed in front of the tool. This behaviour can only be detected by the solid simulation, since the shell does not differentiate enough along the thickness.


Skid lines:

If material flows over a small radius or through a narrow drawbead in a forming process, the sheet metal surface changes. If there is now a boundary in the middle of the part between material that has flowed over the responsible radius and material that has not flowed over it, a clearly visible line remains in the part, the so-called skid line. In the solid simulation, skid lines are directly visually recognizable, whereas in the shell simulation one has to take advantage of special postprocess variables to detect them.