Alternatives to Bore and Face Grinding

Aug. 25, 2011
A compact system that achieves submicron bore-to-face perpendicularity and mirror finishes
The Nagel Precision Inc. honing and cup wheel-face Super Finishing System.

A new honing and cup wheel-face, super-finishing system, developed by Nagel Precision Inc. for small- and medium-volume production, is a lower-cost and higher-quality alternative to ID and face grinding. The compact system combines ECO 40 honing and SPV 150 cup-wheel facing in a single installation, and it generates submicron bore-to-face perpendicularity and mirror finishes on bores, as well as faces, for a fraction of the cost of an ID or face grinder.

However, for parts with smaller diameters and relatively deep bores (length-to-diameter ratio of 2:1), honing has a real advantage in speed of material removal. For bores with a length-to-diameter over 5:1, deflection of the grinding spindle will cause the bore to taper. If a finer, bearing like plateau-honed finish is desired, neither ID grinding nor double-disk face grinding can achieve it, and a secondary finishing operation typically will have to be instituted.

Finally, it is easier to rework and remove 1 or 2 microns of stock with honing and face finishing, in case it is needed to bring a part into specification. It is very difficult to accomplish this with conventional grinding operation.

The ECO 40 honing head can hone bores up to 50 mm in diameter. In-process air sizing can be embedded in the tool for bores over 25 mm in diameter. The in-process air gage automatically measures the bore form error and make automatic adjustments to correct the form error. Larger bores can be equipped with a dual-expansion system that permits mounting roughing and finishing abrasives in the same honing tool along with the in-process air gage. This results in roughing, finishing and gauging in a single tool, eliminating multiple stations. The SPV 150 cup wheel face finisher finishes the face clamping the part on the bore and generates sub-micron bore-to-face perpendicularity and flatness.

Typical applications include pinion gears, fuel injection components, or any other component that requires fine-surface finish as well as excellent bore-to-face perpendicularity.