1. Thaum tso cov vuas hauv pem teb rau hauv pem teb cua sov yeeb nkab, nco ntsoov khaws qhov sib txawv ntawm cov vuas hauv pem teb, vim cov vuas hauv pem teb feem ntau muaj cov yam ntxwv ntawm thermal expansion thiab contraction, yog tias tsis muaj qhov sib txawv ntawm cov vuas hauv pem teb thaum lub sij hawm. cov txheej txheem nteg yog yog li ntawd, cov vuas hauv pem teb yog nquag mus rau hollowing thiab cracking nyob rau theem tom ntej. Tsis tas li ntawd, ua li ntawd kuj tuaj yeem them nyiaj rau qhov tsis xws luag los ntawm cov nplais loj yuam kev.
2. Cov vuas pem teb feem ntau yuav thiab thauj los ntawm lwm qhov chaw. Tom qab koj yuav cov vuas hauv pem teb, nws yog qhov zoo tshaj rau khaws cia rau ob peb hnub, vim tias qhov kub thiab txias ntawm txhua qhov chaw sib txawv, thiab yuav muaj kev hloov pauv me ntsis thermal expansion thiab contraction. Tom qab ob peb hnub ntawm kev tso kawm, cov vuas hauv pem teb yuav hloov mus rau qhov kub thiab txias tam sim no, kom tsis txhob deformation ntawm cov vuas hauv pem teb nyob rau theem tom ntej. Tsis tas li ntawd, tom qab cov vuas hauv pem teb tau tso, yuav tsum tsis muaj cov khoom hnyav lossis ntse ntawm qhov chaw, txwv tsis pub cov kav dej hauv pem teb hauv qab cov vuas hauv pem teb yuav raug crushed.