Ua ntej ntawm tag nrho cov, peb yuav tsum to taub cov hom tshuaj pleev ib ce ntim. Tam sim no, cov thawv ntim tshuaj pleev ib ce hauv khw feem ntau suav nrog lub raj mis yas, iav fwj, txhuas fwj thiab hoses. Txhua lub thawv muaj nws tus yam ntxwv, thiab peb yuav tsum xaiv raws li peb tus kheej xav tau.
Lub raj mis yas yog cov khoom ntim khoom kom zoo nkauj tshaj plaws, uas muaj cov yam ntxwv ntawm lub teeb yuag, ruaj thiab nyab xeeb. Txawm li cas los xij, lub raj mis yas kuj muaj lawv qhov tsis zoo, xws li yooj yim deformation, yooj yim rau kev cuam tshuam los ntawm qhov kub thiab txias, yooj yim los tsim hluav taws xob zoo li qub. Yog li ntawd, thaum xaiv lub raj mis yas, peb yuav tsum tau xyuam xim rau xaiv cov khoom uas muaj cov khoom zoo thiab muaj zog.
Lub raj mis iav muaj cov yam ntxwv ntawm kev tiv thaiv corrosion, kub tsis kam thiab yooj yim tu, uas yog tsim rau khaws cov tshuaj pleev ib ce qib siab. Tab sis cov iav fwj kuj tawg yooj yim thiab yuav tsum tau ceev faj thaum siv lawv. Tsis tas li ntawd, lub siab pob tshab ntawm cov iav fwj tso cai rau peb pom cov xim thiab kev ntxhib los mos ntawm cov tshuaj pleev ib ce.