Emhlabeni wokukhishwa kukaphethiloli, ubuchwepheshe bokhola buqhubeka nokuguquka ukuhlangabezana nezidingo eziyinkimbinkimbi zomkhakha wamandla wanamuhla. Ingxenye eyodwa ebalulekile yalobu buchwepheshe yi-PDC (Polycrystalline Diamond Compact) yokubhola. Yenzelwe izinhlelo zokusebenza ezithile, lawa mabhithi adlala indima ebalulekile ekwenzeni ukusebenza kokubhola, ikakhulukazi ezimweni zokuma komhlaba eziyinselele. Cha.