As we all know that automatic driving and electric car technology has been very much used in the world nowadays & India is also a part of that. However, the production of clean diesel engines in India & other countries like Europe is a challenge. A turbocharger is used in clean diesel engines, and as the parts materials, nickel-base superalloys are used. The machining of these materials is very difficult and as the finishing process grinding is used until now. So, the shortening of the cycle time & the reduction of the cost is another big problem. In this experiment valve, stem machining investigates experimentally the possibility of the substitution from conventional centreless grinding to external turning. The result of this experiment was that the surface integrity was able to be obtained by external turning with the CNC lathe within the range of customer demand. The opposed twine spindle CNC lathe used in this study was able to lead to success in the shortening of the machining time, the cycle time, and the reduction of the cost too.Keywords: Turning, Surface integrity, Inconel 625, Tool wear, Shortening of cycle time, Reduction of cost.