Hi, I’ve recently created a robot in Blender and I’d like to export it to UE, but I have a problem. I have already created lots of materials for my robot, and I don’t know how to import them to UE (not textures). How can I do that?
From my understanding the FBX pipeline supports very basic material transfers, e.g. diffuse maps/normal maps/etc. You can forget trying to transfer advanced materials with reflections/refractions/etc. You’re better off learning UE4’s material system.
When you import your robot UE4 should automatically make each individual component’s material. These will be titled material0, material1, etc and will appear in the same folder. If you double click it to the open the editor, you can set your specific settings there. If you want to make something reflective for instance right click and choose a scalar constant, enter the value o (or 1) and connect it to the metalic input. Set roughness to 0 too.
Ok thank you 
These will be titled material0, material1, etc and will appear in the same folder.
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if you name the materials in blender they should have the same name in UE4 once you import, its best to get the name you want in blender first because if you import multiple models into UE4 that have the same material names they could overwrite each other or cause other issues.
Just a short side note -> dont use too many materials as they are not so good for the performance = drawcalls 
It’s better when you try to create good uv maps for your mesh