Tam sim no, lub Hoobkas muaj cov ntaub ntawv raw txaus, tag nrho cov no yog los ntawm cov tuam txhab muaj npe nrov hauv tsev.Tom qab txhua batch ntawm raw khoom tuaj txog, peb lub tuam txhab yuav sim tag nrho cov khoom, hardness, tensile quab yuam, thiab loj.
Thaum tsim nyog, lawv yuav muab tso rau hauv cov khoom siv raw khoom.