Kev txiav cov txheej txheem, yog lwm kauj ruam tseem ceeb ntawm aluminium ntawv ci khoom ntau lawm, nws txoj haujlwm yog qhov ntim kev faib tawm (yug rau txais cov khoom lag luam yob txhuas ntawv ci), qhov thib ob yog shear: yog cov khoom lag luam ntawm dov tawm cov khoom, hlais mus rau cov neeg siv' s; qhov xav tau ntawm qhov dav, yob taub, tab sis tseem yuav coj nws hauv cov txheej txheem ntawm cov dov ntawm cov khoom uas tsis ua tiav, xws li super tuab, qhov tsis xws luag xws li wrinkling thiab cov menyuam tshem tawm. Rau cov neeg siv, txiav txheej txheem yog txheej txheem ua tiav kawg, yog li qhov ua tau zoo ntawm cov khoom feem ntau nyob ntawm cov txheej txheem ntau lawm ntawm kev txiav. Raws li cov hnub, cov tseev kom muaj rau lub tshuab txiav thiab kev ua haujlwm ntawm cov haujlwm tseem ceeb tseem ua tau nce ntxiv.
Raws li qhov sib txawv tuab ntawm cov ntawv ci txhuas, lub tshuab txiav tawm tau muab faib ua cov ntawv ci tuab thiab ntawv ci nyias. Raws li txoj kev sib txawv ntawm kev siv lub tshuab winding teeb tsa, thiab tuaj yeem muab faib ua lub tshuab txiav ntsug (ob txoj haujlwm winding piv rau qhov chaw ntsug av) thiab kab rov tav txiav tshuab (ob txoj haujlwm winding txheeb ze rau hauv av theem haujlwm)