strange shading strip

[miroslavm]

After importing file .OBJ to blender i explore a strange shade/strip on material in rendered mode.
Most likely it is something wrong with shading, because when i turn off shading of object, strip dissapear.
Maybe importing/exporting. What kind of issue can be that?

Object is original .step format, opened in MoI3D software, then exporting as a .OBJ.

Attachments

strange_shading.blend (700 KB)

[Richard_Marklew]

Select all vertices and removes the hundreds of double vertices (W / Remove Doubles)

Then divide the large multi edged face into simpler faces

[miroslavm]

Thank you very much