Lub luag haujlwm tseem ceeb ntawm roughing yog kom tshem tawm sai sai 70%-80% ntawm cov khoom siv ntau dhau los ntawm txhua lub tshuab ua haujlwm ntawm qhov khoob, ua rau cov khoom ua haujlwm zoo ib yam ze rau cov khoom tiav. Lub hom phiaj tseem ceeb ntawm pwm roughing yog ua kom cov khoom tshem tawm ntau tshaj plaws hauv ib lub sijhawm. Nyob rau tib lub sijhawm, lub roughing theem kuj npaj lub workpiece lub geometric contour rau tom ntej semi-tiav. Cov theem no, los ntawm kev tsom mus rau kev ua cov nyiaj pub dawb loj dua, tuaj yeem txo qhov kev txiav ntawm kev ua tiav tom ntej.
Roughing yog thawj theem ntawm cov txheej txheem machining. Nws lub luag haujlwm tseem ceeb yog tshem tawm feem ntau ntawm cov khoom siv ntau dhau los ntawm qhov chaw seem, ua rau nws cov duab thiab qhov ntev ze rau cov khoom tiav. Cov txheej txheem no txhawm rau txhim kho kev ua haujlwm ntau lawm thiab feem ntau siv cov kev txiav loj dua, ua rau muaj qhov siab dua qhov roughness thiab qis dua tom qab machining. Raws li ib tug precursor rau semi-siav thiab tiav, roughing zoo disperses machining yuam kev thiab reserves tsim nyog nyiaj pab rau cov txheej txheem tom ntej.
