The ABCs of hard part turning on CNC lathes
Hard part turning is the turning of steel with a hardness over 45 HRc (typically in range 55-68 Hrc). It is more cost effective than grinding. Compared to grinding, it can cut machining time and costs by up to 75 %, and also offers improved flexibility, better lead times.
Hard part turning is done with Cubic Boron Nitride (CBN). Ceramics are less popular, and can be used for workpiece materials between 50-60 HRc. The turning is done dry, without coolant.
Compared to grinding, these are the benefits of hard part turning:
– Better machine utilization – same machine is used for external and internal machining (in grinding you would 2 need machines, which means 2 setups).
– Lower machining time.Lower cost per part, because turning is a faster and cheaper process than grinding.
– Complex part shapes can be machined in one set-up.
– No coolant is used, hence more environment-friendly (no grinding sludge).
– Saves the cost of coolant, which can be up to 15 % of machining cost.
Hard part turning is popular in turning automobile parts, particularly drive-train parts like pinions and shafts, gears and crown wheel.
