The objective is to remove a small layer of the material affected by the cutting process. Once this layer is removed, the remaining surface represents the true grain structure of the material.

To accomplish this task you are required to apply three grinding procedures.

Grinding

          Rough Grinding using 240 grit sand paper:

• This is a corrective technique needed to remove gross surface irregularities. Additionally, sharp edges produced by the molding process are removed.

  The system is preset with a grinding program in three steps.  Note the preprogrammed settings for your report, including the revolutions of the wheel, application time, and the direction of rotation. Please note that between steps in the grinding process the specimen should be thoroughly washed to prevent abrasive particles from being carried to finer grit papers.

  Medium Grinding using 400 grit sand paper: This step continues to progressively remove course scratches and deformations from the surface.  Be aware that the preprogrammed step indicator has incremented to step 2. Note any difference in settings.

   Fine Grinding using 600 grit sand paper:  this is the final grinding step and leads to the polishing.

 Polishing 

         Rough Polishing using a 9 or 6μ Diamond compound in solution:  

• This step removes material faster and cleaner than other abrasives in conjunction with a nylon polishing cloth on the wheel.  Apply the diamond abrasive uniformly over the polishing cloth.

           Final Polishing using a 3μ Aluminum compound in solution:  

  The final polishing step should provide a scratch free surface using a wheel with a microcloth. Rotate the sample in a direction opposite the wheel rotation. The material removal at this step is extremely low. This step is just a final polish, it will not correct errors committed in the previous steps. Wash the sample in alcohol immediately or the polished surface will oxidize.