How to Cut Finishing Times of Aircraft Blisks From Several Days to a Few Hours

To a large extent, the surface finish of blisks (blade integrated disks) used in aircraft and other turbines affects their airflow characteristics, overall efficiency, fuel consumption and noise emissions. Surface finishing of blisks was previously done manually with grinding disks and other manually operated tools. Due to the “human factor,” the quality of the final finish could vary greatly between parts, with certain surface areas frequently not even finished at all. Now, for efficient surface finishing of blisks Walther Trowal (Grand Rapids, MI) has redesigned their CM vibratory system to ensure that workpieces receive a uniform, homogeneous high quality finish with absolutely repeatable results. For the consistent and high quality finishing of circular high value components, the new CM rotary vibrator was redesigned in close cooperation with leading turbine manufacturers to make it more suitable for treating all kinds of turbine components.

The CM system allows deburring and general surface improvement of components with diameters of up to 980 mm. Single workpieces are mounted to the inner dome of the processing bowl. The height of the inner dome itself has been drastically shortened. After grinding media has been filled into the bowl, a vibratory motor causes the complete work bowl to vibrate. This causes a constant “rubbing” of the media against the fixed workpiece. Since the “rubbing” action is highly homogeneous, a uniform, even finish on all surface areas of the disk and blades is achieved. After completion of the process the surface roughness readings amount to Ra = 0.2 µm to 0.4 µm. Starting with an initial surface roughness of Ra = 4 µm to 5 µm, the desired finishing results are achieved within about five to six hours. Compared to this innovative method, the manual finishing of blisks can take several days.

“Especially for the production of turbine components, any manual manufacturing operations must be viewed with great skepticism because the quality of their work will vary greatly,” said Christoph Cruse, a sales manager at Walther Trowal, commenting on the special conditions prevailing in the aerospace industry. “With our new finishing machine, we have completely eliminated the vagaries of the human factor. And we can reduce the finishing times for blisks from several days to just a few hours.” For finishing of blisks the company recommends special finishing media type V 2030 that produces very smooth surface finishes on materials and shapes that are typical for blisks. V 2030 media is globally approved for the aerospace industry.

Walther Trowal, 4540 E Paris Avenue SE, Grand Rapids, MI 49512, 616-455-8940, www.walther-trowal.com/us.