Cov laj thawj thiab ntsuas kev txhim kho rau qhov tawg ntawm qhov tuag stamping qhov yog:
1) Cov ntug txiav tau hnav los yog chipped, thiab qhov ua kom tawv tawv yog qhov qis, thiab txiav ntug xav tau kev cob qhia
2) Yog tias qhov kev tshem tawm loj dhau, cov txiaj ntsig tsis pom tseeb tom qab kev qhia txog riam riam, thiab nws yog qhov yuav tsum tau txuas ntxiv tswj kev ua kom raug ntawm lub convex thiab concave pwm lossis hloov kho qhov kev tshem tawm;
3) Qhov sib txawv tsis tsim nyog nce thiab nqis los yog xoob, thiab qhov khoob khoob yuav tsum tau kho ntxiv kom paub meej tias hnav ntawm tus qauv qhov lossis ua qhov tseeb ntawm cov pwm ib feem;
4) Cov pwm tau ua tsis ncaj nce thiab nqis, nws yog qhov tsim nyog los hloov phau ntawv qhia lossis rov ua dua cov pwm
