M'zaka zaposachedwa, ukadaulo wakubowola wapita patsogolo kwambiri, ndipo chimodzi mwazinthu zazikulu zomwe zikuyendetsa kusinthaku ndi chodula cha PDC. PDC, kapena polycrystalline diamondi yaying'ono, odula ndi mtundu wa chida chobowola chomwe chimagwiritsa ntchito kuphatikiza kwa diamondi ndi tungsten carbide kupititsa patsogolo magwiridwe antchito ndi...
Werengani zambiri