Cov cuab yeej kho vajtse hais txog hlau, hlau, txhuas thiab lwm yam hlau los ntawm forging, calendering, txiav thiab lwm yam kev ua lub cev, tsim rau ntau yam khoom siv hlau. Muaj ntau hom khoom siv kho vajtse, raws li kev siv cov khoom sib faib, tuaj yeem muab faib ua cov cuab yeej kho vajtse, ...
Nyeem ntxiv