Machine Polishing Stainless Steel

Below are the supplies and steps you will need to get a smooth finish using an angle or bench grinder.

Supplies: Angle grinder or bench grinder, Buffer and buffing pad, Abrasive (sandpaper), Acetone or alcohol, Soft sponges or clean cloths, Polishing compound, White vinegar (optional)

Step:

1. Clean And Prepare The Stainless Steel

Stainless steel surfaces must be thoroughly cleaned before polishing. If left in place, foreign matter can scratch and dull the surface, damaging rather than enhancing it. Remove any sticky residue with acetone or alcohol. Then clean the surface with hot soapy water and a sponge or soft cloth: do not use steel wool or any other object that could damage the stainless steel. Make sure the surface is completely dry before continuing.

2. Level The Surface

Using 80-120 grit sandpaper, smooth out the rough areas once you have obtained a clean surface; if the steel is welded, the bead must be removed. Take your time and avoid over-sanding the surface and creating a low spot. For large parts, an angle grinder is the easiest tool to use, while a bench grinder may be more appropriate for small parts. Be sure to clean the workpiece again before moving on to the next step, as any residual contaminants could affect the final product.

3. Sand The Surface

As soon as the imperfections are reduced, start using sandpaper instead of the grinder. For metals with a polished finish, you can start with 120 grit paper and gradually move on to finer grit as the surface becomes smoother. As a general rule, you should go from 240 grit to 400 grit, then to 600 grit and finally to 1200 grit. For a mirror finish, you can go even further by using 2000 grit sandpaper.

Set your sander to between 4,000 and 6,500 rpm for polishing stainless steel. Make sure you move the sander at a 90° angle to the visible scratches. (Each time you change the grit of the sandpaper, move it at a 90° angle to the previous movement). As soon as the stainless steel part has an even, satin finish, you're ready to move on to the next step. Finish by wiping the surface of the steel with a soft sponge or cloth soaked in water.

4. Polish

Choose a polishing paste designed for stainless steel. Apply a small amount to your polishing wheel and slowly move the machine up and down the length of the surface. Be sure to overlap your paths to avoid leaving polishing lines on the surface. It is equally important to keep the pad moving to avoid burning the surface of the steel.

Polishing stainless steel removes scratches and imperfections so that debris cannot collect in microscopic crevices. Thanks to this multi-stage process, imperfections are gradually smoothed out and the metal's best qualities are restored. Buffing takes time, but it's the only way to repair the surface and give it that attractive, long-lasting mirror finish.