Single point diamond machining of ferroelectric materials

One of the most important ferroelectric ceramic materials used in a wide range of applications is the lead zirconate titanate solid solution series (PZT). The ability to machine ferroelectrics in a ductile manner and by so doing reduce sub-surface damage, could eliminate the need for subsequent lapping and polishing and thus reduce production costs. Fracture mechanics techniques were used to investigate the localised elastic/plastic behaviour in these materials. The possibility of machining brittle materials using single point diamond turning in a 'ductile mode' has been investigated by many researchers in recent years and for this study poled and unpoled PZT ceramics were single point diamond turned under different machining conditions and ductile machining has been achieved. X-ray diffraction (XRD) indicates the degree of domain reorientation caused by machining, and it is suggested that the strain generated by re-orientation accounts for brittle damage. Appropriate poring can have a marked effect on the brittle/ductile machining response.