Honing process produces less than 2-micron cylindricity in long, small-diameter bores

May 7, 2014

Sunnen Products Co. offers the high-precision Single Stroke Honing® process, which achieves cylindricity and straightness of less than 2 microns in bores up to 10 times longer than diameter. Developed to meet leak-free requirements for high-pressure hydraulic systems, the process is almost 200 percent more accurate than anything previously achievable for long, small-diameter, tandem bores, the company reports.

The precise fit between the sliding spool and valve body maintains the internal seal in that area. Precision cylindricity and straightness in the bore help ensure uniform clearance between the moving parts from top to bottom in the valve, allowing free movement of the spool without leakage around it.

The single-pass honing process sizes and finishes a bore with a series of progressively larger superabrasive tools adjusted to a preset diameter. The honing tools rotate while passing through the bore one time and then withdrawing. The machine's servo-controlled stroking system provides flexibility with adjustable speed and various feed profiles, such as pecking, short stroke, and dwell. Column feed and spindle speed can be varied throughout a cycle using the machine control.

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