How to use sandpaper for sharp hairline on 430 stainless

Hello all :

We use the new industrial machine to processing the surface of the stainless coil . The customers want the finish look very sharp and clear. but the question is that nowadays we use the 180-grit- sandpaper [affil link] to grind , and every about 1000m we have to change the sandpaper to make sure the quality same from the beginning to the end (and the hairline is still not very clear...more like the no.4.... ). could anyone provide the suggestion about how to process the hairline on type 430 stainless steel and make the finish clear by sandpaper .. very appreciate!

Not sure what you mean by the word clear; however, it sounds as if your uneven finish could be corrected by a tensioning device if you are working parts automatically. If not, you may have to use 2 different abrasive wheels. One to rough up surface and other to even out or smooth to specifications. A 2 step should get more uniformity.