Compared to purchasing and operating a dedicated honing machine, benefits include cost reductions and the ability to combine general machining with honing on the same platform, eliminating a separate set-up.

The accompanying video shows cylinder bores being roughed, finish honed and brushed using the technique.The process is performed on a Hurco VMX-series BT40 vertical machining centre as follows. First, a touch-probe held in the tool magazine is deployed in the spindle to verify the bore diameter and ensure that the correct program is loaded. The probe then takes another measurement further into the bore to ensure that it is straight enough to be machined. Assuming it is, the diameter is rough bored to the correct size for honing. A honing tool with a standard back end is then exchanged automatically into the spindle and through-coolant is used to activate and control expansion of the tool, pushing the stones outward while the hone reciprocates and rotates. An in-process air gauge system enables bore size to be continuously monitored.

Once the programmed diameter is achieved, a signal is sent from the air gauge to the Hurco Max control of the machining centre to stop the honing cycle. Finally, the bore is brushed with a soft finish hone to smooth the high points and provide the required surface finish. Once again, coolant is used to control expansion and pressure.

Interested manufacturers in Britain and Ireland should contact UK subsidiary Hurco Europe, High Wycombe.