Experimental and numerical investigations on the effect of varying AlTiN coating thickness on hard machining performance of Al2O3-TiCN mixed ceramic inserts

The present work focuses on numerically and experimentally investigating the performance of uncoated, and multi-layer AlTiN coated (coating thickness ranging from 2 to 4 μm) Al2O3-TiCN composite (mixed) ceramic cutting tools while hard turning of AISI 52100 steel (62 HRC). 3D finite element model was developed taking into consideration a hybrid friction criterion to study the behaviour at the sticking and sliding zones of friction numerically. Later, deposition of AlTiN coating was executed on uncoated Al2O3-TiCN inserts using cathodic arc evaporation process. Coating thickness was evaluated from the fractography of coated tools using field emission scanning electron microscopy (FESEM). Turning experiments under dry cutting conditions were performed on a heavy duty lathe machine equipped with a dynamometer using both coated and uncoated cutting tools. Also, wear analysis of the cutting tools was carried out using optical microscopy, scanning electron microscopy (SEM) and FESEM. Comparison of machining responses showed a close agreement between finite element and experimental studies. It was observed from the numerical and experimental results that AlTiN coated tool with 4 μm coating thickness exhibited best machining performance on Al2O3-TiCN inserts during hard turning of AISI 52100 steel.