Wear Behaviour of WC-Co Hardmetal Cutting Tools in Dry Machining of Nigerian Locally Produced Cast Iron

This study investigates the wear behaviour of WC-Co cemented carbide cutting tools during dry turning of grey cast iron produced by foundries in Nnewi, Anambra State, South East Nigeria, and correlates tool wear progression with the microstructural variability of the locally cast material. Understanding the machinability of locally produced cast iron is commercially important for the Nnewi automotive parts manufacturing cluster, where tool cost management is a significant profitability factor. Lathe turning experiments are conducted using ISO indexable WC-Co inserts (ISO SNMG designation) on a conventional CNC lathe at cutting speeds of 150, 200, and 250 m/min, feed rates of 0.1 and 0.2 mm/rev, and a depth of cut of 1.5 mm. Flank wear is measured by optical microscopy at regular machining intervals following ISO 3685 tool life criteria. Worn tool surfaces are examined by SEM-EDX to characterise wear mechanisms. Workpiece cast iron from five foundries is characterised by microstructural analysis and hardness testing. Findings reveal that cutting speed is the most influential parameter, with tool life decreasing by 55 percent as cutting speed increases from 150 to 250 m/min. Cast iron from foundries with coarser graphite flake morphology and higher hardness reduces tool life by up to 40 percent compared to finer-microstructure variants, demonstrating the impact of casting quality on downstream machinability. Keywords: WC-Co cutting tool, tool wear, cast iron, dry machining, Nnewi.