There are needles designed specifically for metallic thread. Most that I know of are a 90/14, but they have a eye that is specially designed to allow the metallic thread to run without fraying or shredding.
You should be able to embroider on hats with an 80/12. I ran some last week using the metallic thread. Make sure your design is not too dense for the metallic, take some stitches out.
what size needle for metallic threads? 
