Aim: This research compares the effect of Aluminum Titanium Nitride (AlTiN) coated tungsten carbide (WC) insert tool and uncoated HSS insert tool  in CNC green machining (turning process) of High Strength Steel EN3B for improving rate of material removal and surface finish. Materials and Methods: The high strength steel EN3B material jobs which are machined with AlTiN coated WC tool are an experimental group and those jobs are machined with uncoated High Speed Steel (HSS) insert tool in the same green machining process as the control group. The total sample size is 32 (16+16) and the G power 80% was used for prediction of group size. Results: The results revealed that the feed rate was the most important parameter affecting the surface roughness and  depth of cut and also affects cutting force and power. The significance of p Value was found as 0.021for material removal rate and 0.001 for surface roughness observations which is lesser than 0.05. Conclusion: The material removal rate averagely improved 46% and the Surface roughness averagely reduced by 54% with use of novel AlTiN coated WC tool insert than conventional HSS tool insert.