31.08.2014 Views

ASNT Level III- Visual & Optical Testing

My Level III Self Study Notes Reading 4 Section 4B

My Level III Self Study Notes Reading 4 Section 4B

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

7.2.3 Grinding and Polishing<br />

Fine grinding and polishing are needed for visual tests of<br />

small structural details, welds and the effects of heat treatment.<br />

Finer grinding usually is done with 80 to 150 abrasive<br />

grit followed by 150 to 180 grit and finally 400 grit (an American<br />

indication of grit size, 400 being the finest). At each<br />

stage, marks from previous grinding must be completely removed. Changing<br />

the grinding direction between successive<br />

stages of the process aids the visibility of previous<br />

coarser grinding marks. Coolant is required for grinding and<br />

typical abrasives include emery, silicon carbide, aluminum<br />

oxide and diamond.<br />

Charlie Chong/ Fion Zhang

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!