An aerospace structural component in annealed titanium with a 25.8 mm long uninterrupted through bore in the Ø66 mm range was honed directly on a Makino T1 in two stages, in the same setup as the preceding machining operation.
For precision honing, DIAHON coolEXact was used in OP1 for size control and DIAHON coolEX in OP2 for fine and finish honing. Surface measurements were Ra = 0.166 µm / Rz = 1.351 µm and Ra = 0.140 µm / Rz = 1.403 µm. Subsequent form measurements confirmed cylindricity < 4 µm.
OP1 - honing / size control: DIAHON coolEXact 8L66, K064, spindle speed n = 200 rpm, pressure = 30 bar, overstroke approx. 12.5 mm (50%). Documented stock removal up to approx. 3 µm per stroke.
OP2 - fine and finish honing: DIAHON coolEX 8L66, K030, spindle speed n = 200 rpm, pressure = 30 bar, overstroke approx. 12.5 mm (50%). Documented stock removal up to approx. 1 µm per stroke.
The coolEXact/coolEX combination separates size control from fine surface finishing.
Surface measurement 1: Ra = 0.166 µm; Rz = 1.351 µm; Rmax = 1.618 µm; Rpk = 0.180 µm; Rk = 0.513 µm; Rvk = 0.280 µm.
Surface measurement 2: Ra = 0.140 µm; Rz = 1.403 µm; Rmax = 1.628 µm; Rpk = 0.136 µm; Rk = 0.416 µm; Rvk = 0.302 µm.
Cylindricity: Subsequent form measurements confirmed cylindricity < 4 µm.
Both the Ra < 0.8 µm surface requirement and the specified cylindricity were achieved.
Precision honing of annealed titanium was stable in this application. Bore size was controlled using DIAHON coolEXact in OP1; subsequent honing with DIAHON coolEX in OP2 enabled additional low-stock-removal strokes and a fine finish.
Honing in the same setup as the preceding machining step reduces re-clamping error. The combined size-honing and finish-honing strategy achieved Ra down to 0.140 µm and confirmed cylindricity < 4 µm.
Can a Ø66 mm titanium bore be precision honed on a 5-axis machining center?
Yes. This application was honed on a Makino T1 with HSK-A100 and emulsion coolant.
Which DIAHON technologies were used?
DIAHON coolEXact in OP1 for size control and DIAHON coolEX in OP2 for fine and finish honing.
What surface roughness was achieved?
Measured values were Ra = 0.166 µm and Ra = 0.140 µm.
Was the specified cylindricity achieved?
Yes. Subsequent form measurements confirmed cylindricity < 4 µm.
The project demonstrates a robust two-stage DIAHON honing process for an aerospace structural component in annealed titanium. Honing with coolEXact and coolEX achieved Ra = 0.140-0.166 µm, while subsequent form measurements confirmed cylindricity < 4 µm.
The combination of DIAHON coolEXact for size control and DIAHON coolEX for finishing is therefore suitable for precision honing this short Ø66 mm titanium bore directly on a 5-axis machining center.