1. Tsim: Tsim pwm kos duab raws li qhov xav tau cov duab, qhov loj, thiab cov khoom ntawm cov khoom.
2. Kev tsim khoom: Cov khoom siv raw rau kev ua pwm feem ntau yog cov khoom siv hlau xws li cov phaj hlau thiab cov kav hlau. Ua ntej, cov ntaub ntawv raw yog txiav mus rau hauv cov duab ntawm cov pwm siv lub tshuab txiav, thiab tom qab ntawd ua tiav siv cov tshuab xws li fitters thiab machining chaw.
3. Kev sib dhos: Sib dhos cov txheej txheem ua tiav rau hauv kev sib dhos ua tiav pwm.
4. Kev Kho Kom Zoo: Kho thiab kho cov pwm kom paub meej cov khoom zoo.
