Vol. 12
January Issue
Year 2011

Cover Page

in Vol. 12 - January Issue - Year 2011
Renowned turbine manufacturer utilizes state-of-the-art Rösler shot peening technology. A Significant Efficiency Boost for Fan Blade Production

A 6-axis articulated robot moves the blast nozzles ensuring an absolutely precise blast pattern on the parts

Wet blast system for peening of air foils bent in 3 dimensions

The spiral separator guarantees a constant high blast media quality by discharging broken down and deformed blast media

For peening a wide variety of fan blades for aero engines, Rösler has developed highly automated shot peening and wet peening systems incorporating features which already reflect future technical requirements.

The innovative, low weight propulsion units made by this turbine manufacturer are characterized by their relatively low noise emissions and energy efficiency. Manufacturing of these units requires a total focus on materials like titanium and aluminum. The inducement of compressive stresses on the surface of these light metals by shot peening significantly improves their torsion and corrosion resistance and their resistance against fatigue cracks.

For the peening of large fan blades the customer installed two custom-engineered Rosler shot blast systems - one for wet peening and the other one for dry shot peening. To provide for future turbine developments requiring even larger fan blades, both blast systems were designed for maximum parts sizes of 1,650 mm x 550 mm. The high degree of automation of both peening systems ensures that they fully meet the stringent productivity standards prevalent in the aerospace industry.

Shot peening of blade roots

The roots of fan blades are peened in a system that is equipped with a dual station turn table. The two work stations are separated by a dividing wall featuring a pneumatic seal. A safety light curtain is installed for the protection of the operator. This design allows the loading and unloading of parts in one station while the parts in the other station are being peened in the blast chamber. Special work piece fixtures were developed to prevent nicking or other damage to the air foils during the shot peening cycle. These fixtures ensure that only the roots are exposed to the blast stream, while the rest of the fan blade is precisely masked with a wear resistant material. The peening process itself takes place by six (6) nozzles simultaneously throwing steel shot onto one side of the fan blades placed in upright position. A 6-axis articulated robot ensures the exact nozzle movement in the curved area of the fan blades. After a preset processing time the fixtures automatically rotate by 180° for peening of the other side of the fan blades.

An air wash separator, a vibratory screen separator, and a spiral separator ensure that the blast media is perfectly cleaned and classified so that it can be re-circulated, and that it always meets the strict quality standards stipulated for the shot peening process.

Multi-hopper wet peening system with 16 nozzles for air foils

The customer utilizes a wet peening system from Rösler for the peening of air foils. This system has a stainless steel cabin that is equipped with 16 nozzles. In this system a 4-axis CNC drive unit is inducing the movement of the 16 nozzles. To make sure that the blast media always hits the surface of these complex, 3-dimernsionally shaped components at the pre-determined angle, the nozzles make an "S"-type movement, while pivoting at the same time.

A multi-hopper system is utilized for the controlled cleaning and classification of the glass bead blast media. Compared to other wet blast systems usually only equipped with a stirrer, the Rösler system utilizes highly wear resistant pumps which are constantly re-circulating the media/water slurry. This ensures that an optimal ratio of glass beads to water can be maintained. The media to water ratio is continuously monitored online as well as by an optical measuring system. Broken down glass beads that are no longer usable are discharged with a hydro-cyclone. An additional vibratory screening of the blast media takes place in by-pass mode. The process water containing glass fines passes through a Z 800 centrifugal filter for removal of these tiny glass particles. The cleaned liquid is then re-circulated back into the peening system.

Multiple process controls

In order to fulfill the stringent aerospace standards regarding process stability and repeatability, all process parameters are monitored on a continuous basis. For example, in both peening systems each nozzle is equipped with an air flow measuring & monitoring device. In addition, both systems monitor the blast pressure and measure the blast media concentration.

For Information:
Barbara Müller
Rösler Oberflächentechnik GmbH
96190 Untermerzbach, Germany
Tel. +49.9533.924-0
Fax +49.9533.924-300
E-mail: info@rosler.com