Jui-Chang Tsui, Ying-Hung Chen, Ping-Yen Hsieh, Ju-Liang He, Feng Chia University, Taichung City, Taiwan
The slitter cutters, usually made of tungsten carbide material, for aluminum capacitor foil cutting is crucial for the performance. Poor cutting leads to burrs and cracks on the edge of capacitor aluminum foil, which significantly affects the reliability of the assembled capacitors. To address this issue, high-power impulse magnetron sputtering (HiPIMS) was employed in this study to deposit dense and uniform TiB_₂ coating on the edge of both male and female slitter cutters. TiB₂ as the coating material is considered for its exceptional high hardness and excellent dry lubricity, making it possible for improved cutting anodized capacitor aluminum foil where their surface exhibit high hardness γ-Al_₂O_₃.
In this study, HiPIMS TiB_₂ coating was deposited on the edge of both male and female slitter cutters. Two sets of male slitter cutter materials were chosen with their hardness value of 953 HV and 1554 HV, corresponding to the cobalt content of 22 at.% and 18 at.%, respectively. The obtained HiPIMS TiB_₂ coatings exhibits excellent adhesion, regardless of the slitter cutter materials. Field test results of slitter cutting show that the low-hardness slitter cutter presents poor cutting performance when after coating, while the high-hardness slitter cutter presents excellent cutting performance after coating. Observation on the worn area suggests that the low-hardness slitter cutter even with TiB_₂ coating can not bear the cutting shear stress and the spalled TiB<>sub>₂ coating incorporate into contact surface and devastate the edge of slitter cutter. On the contrary, using high-hardness slitter cutter, the TiB_₂ coating can be well supported by the substrate bring improved wear resistance to the slitter cutter.