Tom qab cov khoom raug tshem tawm ntawm txheej pwm, nws muab tso rau lwm txheej pwm rau kev txhaj tshuaj molding thib ob lawm .Yog li ntawd, feem ntau cov txheej txheem molding no feem ntau yog ua tiav los ntawm ob lub pwm ntawm cov pwm, uas tsis tas xav tau ob chav xim tshwj xeeb dua txhaj tshuaj molding tshuab.