1.Xaiv cov kev qhia tshwj xeeb thiab cov ntaub ntawv zoo: phim lub thickness thiab hardness ntawm daim ntawv, tsis txhob overloading thaum txiav, thiab txo cov ntug chipping thiab hnav.
2.Txoj haujlwm ua haujlwm: pub cov ntaub ntawv ntawm qhov nrawm nrawm, tsis txhob rub tawm thaum cov ntawv kaw, thiab txo cov kev puas tsuaj rau cov hniav
3. Kev tu tsis tu ncua: ceev nrooj ntxuav cov ntawv khib nyiab thiab cov kua nplaum kom tiv thaiv cov impurities los ntawm kev nrawm nrawm, thiab maj mam siv cov tshuaj tiv thaiv - xeb roj raws li xav tau
4.Kev cia zoo: Khaws rau hauv qhov chaw qhuav thiab qhov cua, tsis txhob sib tsoo thiab sib tsoo, thiab tiv thaiv kev ncaj ncees ntawm cov hniav ntug
5.Txhim kho cov khoom siv: xyuas kom meej qhov tseeb ntawm cov cuab yeej tuav thiab lub log siab, nrog kev sib raug zoo, kom lub zog sib npaug
