Txhua tus nyias muaj nyias qhov zoo thiab qhov tsis zoo. Qhov zoo ntawm wpc qhov rooj yog tias tus nqi yog qis me ntsis dua li ntawm qhov rooj ntawm cov khoom ntuj ntoo. Kev tsis zoo: vim tias ntuj ntoo yooj yim cuam tshuam los ntawm huab cua, muaj qhov tshwm sim ntawm ntub dej thiab qhuav shrinkage, thiab qhov chaw sib khi yog yooj yim tawg. Lub rooj tsavxwm ceev yog tsis muaj kev tiv thaiv ib puag ncig.
Qhov zoo ntawm cov ntoo yas qhov rooj: kev tiv thaiv ib puag ncig ntsuab. Kev txuam nrog moulding tsis yooj yim rau deform. Dej tsis tau, noo-pov thawj, tiv thaiv cov kab mob thiab cov pwm hauv cov pov thawj. UV nto kho tau zoo tiav. Qhov tsis zoo: raws li ib hom tshiab ntawm cov khoom siv tiv thaiv ib puag ncig los ntawm txawv teb chaws, cov ntaub ntawv yas ntoo yog siv rau hauv kev lag luam kho kom zoo nkauj nrog cov tsis tshua paub txog ntawm cov neeg siv khoom, cov qauv yooj yim, lees paub zoo hauv cov nroog tsim thiab tsis tshua pom zoo hauv nroog