The Precision Hone tooling system from Sunnen uses integral air gaging and an automatic shutdown device to produce non-contact, in-process bore sizing to tolerances of 0.005 mm (0.0002 inches). They are suitable for honing diesel cylinder liners, compressor cylinders, automotive engines, small engines and aircraft cylinder bores with diameters from 57 mm (2.25 inches) to 300 mm (12 inches).

The air gaging system is a unique feature. Bob Davis, global communications manager for Sunnen explains how it works. "The PH Precision Hone tooling system incorporates air lines into the tool, which conduct pressurized air terminating in small ports on the edges of the tool. A feedback loop in the machine controller measures the pressure, which builds up between the hone head and the wall of the part being honed. As the diameter of the part gets larger, the pressure drops. The gaging system circuitry built into the honing machine measures the pressure and translates it into a diameter. The machine is set up to hone to a certain diameter and automatically stops when that diameter is reached."

The PH tools have multi-stone tool heads that are custom-designed; the number and placement of stones is dictated by the application. Bayonet air connections on the tool heads help initiate fast changeovers. The tools can connect to the rotary feed system of Sunnen's SV-310 for precision stone feeding or the linear feed system of the SV-500 for two-stage roughing and finishing applications. They can also be used with other manufacturers' machines. They include three abrasive options: metal-bond superabrasive (diamond or CBN), conventional abrasive (aluminum oxide/silicon carbide) and plateau brush (abrasive impregnated filament).