Dental Biomaterials Lab | Instruments

Polishing and Grinding SOP

Electricity supply should be ready. Turn the power switch ON (main switch is on the back).
Water supply should be ready. Turn the water valve ON.
When using auto polishing head, compressed air (35-40 psi) should be ready. Turn the compressed air switch ON
Polishing head, rim and panel button must be clean. If not clean, clean with moist towel.
Check polishing discs are clean and ready for use.
Choose proper PPE for eye protection.

Make sure your polishing cloth or grinding paper are mounted properly. It should not be able to slip and all air bubbles must be removed.
Make sure your specimen is suitable for polishing/grinding. The polishing surface must be flat and all edges (top and bottom) must be rounded (not sharp). Otherwise, there is a good chance that the cloth or paper will grab the specimen and pull it from your hand, or the edges may cut the cloth and possibly your hand.
Make sure the rim is in place. Never operate the polisher/grinder without the rim in place.

Start the motor and wait for it to come up to speed. Use less than 100 rpm for hand-hold polish.
Gently lower the specimen to the center of the wheel. Once it is down apply pressure and slowly move it to approximately half way to the edge of the wheel.
Slowly but firmly move the specimen in a clockwise direction.
Use polishing media sparingly. Excess will just go down the drain or splatter all over the table.

Mount the polishing disk on EcoMet as required.
Mount sample holder and make sure the proper selection of pressure mode (single press and multiple press mode) on panel.
Set timer.
Using multiple press holder. Press and hold both green buttons till the holder touches the disc. Then release buttons.
Mount 1.25" dia. specimens into the mount holes. Put the alignment chuck in.
Press both green buttons once.
Use polishing media sparingly. Excess will just go down the drain or splatter all over the table.
Apply less than 15N on polishing cloth and less than 70 rpm. High load may delaminate the cloth and damage specimens. High speed may spin away the polishing paste.
Never polish with the sand paper with metal ring frame. Use sand paper with back adhesive.

Grind from 70 μm - 45 μm silicon carbide disc or 120-230 M sand paper to a reasonable flat surface or expose interested layer.
Polish with 15 μm silicon carbide disc or 600M sand paper to remove large scratches.
Polish with polishing medium 6 μm, 1 μm, 0.3 μm, and 0.05 μm diamond or alumina suspension.
Specimens must be ultrasonically cleaned between two grits of polishing/grinding.
Diamond suspension is very expensive, $750 per gallon. Use sparingly.
Use alumina paste from PSI for soft materials. Nylon finishing cloth (PSI-621-8 or Buehler Microcloth) is best for alumina paste.

When you are completely finished using the polisher/grinder you must do the following:

Turn off the power, air and water of polisher/grinder.
Clean up the disk (platten), making sure you remove the polishing cloth and polishing residue.
Reusable cloth must be rinsed thoroughly, wipe dry, and leave in the designated place with clear mark.
Clean the bowl, giving it a final rinse with water.
Wipe the head holder, buttons, and rim with a moist towel or sponge. Dry them if necessary.
Wipe up the area around the polisher/grinder. Dry it if necessary.

Silicon carbide sand paper 120, 180, 400, 600, 800, 1200, 2000 (Buehler Ltd, Lake Bluff, IL, USA)
Diamond grinding disk, Apex Coarse Grinding Disc, Metal Back, 125 um (Buehler Ltd, Lake Bluff, IL, USA)
Diamond grinding disk, Apex Disc, Metal Back, 45 um, 70 um (Buehler Ltd, Lake Bluff, IL, USA)
Diamond grinding disk, Apex Disc, PSA 125 um (Buehler Ltd, Lake Bluff, IL, USA)
Diamond grinding disk, UltraPrep Disc, PSA 70 um, 45 um, 15 um (Buehler Ltd, Lake Bluff, IL, USA)
6 um (yellow coded), 1 um (blue coded) diamond suspension (Buehler Ltd, Lake Bluff, IL, USA)
l um, 0.3 um. 0.05um alumina suspension paste (Precision Surfaces International, Inc., Houston , TX)

Note: Surface should be shinning after 6um polish, and will be mirror-like after 1-0.3um polishing.
Note: Do not use continuous water on diamond/alumina suspension.
Note: Magnetic disk should be dried to hold magnetic polishing disk strongly.