On a horizontal machining centre, using the VIPER grinding technique, 5-axis machining of a nickel alloy compressor blade involved grinding a radial dovetail root form, including a milling operation.
On a Makino A55 machining centre, three separate demonstrations at UK Makino agent's technology centre in Coventry, underlined the flexibility of the machine as a platform for producing components by grinding and other metal cutting operations in very few set-ups, or even one hit. Five-axis machining of a nickel alloy compressor blade involved grinding a radial dovetail root form followed by a combination of grinding and finish milling of a small-radius scallop, which the grinding wheel was unable to access. Total cycle time was 5.5 min.

Conventionally, blades are first ground and then set up for a second operation on a machining centre.

Savings in handling, fixturing and cycle time are considerable with the Makino solution.

The second component demonstration involved grinding the fir tree root form for a high-pressure turbine blade from solid nickel alloy in a cycle time of 3.5 min.

Normally, such components are ground from a closer-to-form forging on a dedicated grinder.

The most usual production process for this popular aerospace component is in a 'Nagare' cell comprising, say, 10 separate machines tended by five operators to clamp every part once on each machine.

On a Makino VIPER machining centre, parts generally come off complete in two operations, drastically reducing production costs.

Grinding of a radial seal slot, 2.6mm wide by 7.3mm deep over a 200mm chordal length, formed the third demonstration.

Instead of being produced in Inconel, the part was of a less expensive steel, which in this application is more challenging to grind.

Two small, aluminium oxide wheels were used, rather than traditional cubic boron nitride, one for the outside radius and another for the inside radius to achieve perpendicular groove sides.

Dressing was by NC profiling, avoiding the expense and long lead time of full-form dressing (ideal for fast-make situations).

Two-axis control of the grinding wheel plus B-axis positioning of the component achieved the required contouring of the slot.

Another aspect of this demonstration was the manual-assist loader at the front of the machine.

Components were fixtured outside the machining area and transferred with minimal effort to a zero point fixture on the table ready for machining.