求翻译：清洗轴承与外壳，确认无伤痕或机械加工留下的毛刺。外壳内绝对不得有研磨剂(SiC、Al2O3等) 型砂、切屑等。是什么意思？

Clean bearing with shell, confirm no scars or mechanical processing of burrs left. Enclosures have absolutely no abrasive material (such as SiC, Al2O3) sand, chips, etc.