Unique Fixture System Provides Robust CMM Solution

Gas turbine fan blades have precisely engineered aerodynamic surfaces with geometry directly related to engine performance requirements. It can be difficult to inspect the 3D complex aero-shape, with reliable inspection necessary to confirm that the finished product matches the design intent. When using a Coordinate Measuring Machine (CMM) the part must be positioned reliably, otherwise the probe may collide and require re-calibration.

UK based company MetLase, a joint venture company between Rolls Royce and Unipart, was asked to design a repeatable and simple method of locating a complex aero surface for CMM inspection.

Using precision laser cutter and joining technology, MetLase was able to design and build a fixture which held the aero section in place and incorporated a laser sensor to verify that the component to be measured would lie within the CMM’s probe-path envelope. The blade was held securely by distortion-free clamping, enabled by MetLase’s titanium spring technology. The laser incorporated into the fixture demonstrated that repeatable component placement was possible to within ten microns.

The resulting fixture was simple to use, repeatably precise and produced a significant time saving over the previously used inspection methodology.

MetLase’s technology is based on precision laser-cutting, press-brake bending, and a set of patented joining methodologies to suit all applications.

Precision laser-cutting ensures that each component is faithful to its design, capable of cutting simple metals or high-grade, aerospace materials with equal precision, the laser cutter has a precision of less than 10 microns.

Precision cutting on its own is no good, if the joining methodology is then going to deform the metal. MetLase’s patented joining technology utilizes the strength of the parent material without any other interventions and eliminates heat deformation from welding with the mechanical joins, which hold as solidly as a weld.

The twist-dowel is Metlase’s most commonly used fixing method; precision cuts in the material create a dowel which provides the inherent accuracy, the remaining profile can then be twisted with a simple tool to provide a firm joint. This twist can be made permanent, or can be used repeatedly (for design-iteration or re-assembly) many times without damaging the metal. The final fixture solutions using the twist-dowel can also be flat-packed for easy transport and assembled with ease at the final destination.

Twist-dowels are not suitable for all applications, such as those requiring a flush surface, where a flush fastener or slot rivet are used to produce a flush-finished surface.

MetLase roots can be traced back many years within Rolls-Royce where it originated a system that could rapidly solve engineering problems by combining laser-cutting, CNC press-brake and ingenuity, into a system that could rapidly solve a huge class of engineering problems. These principles of rapid-iteration, problem-solving, and automated machining (no manual cutting or welding, and virtually all components being made on the laser-cutter) were adopted by a small internal team at Rolls-Royce, known internally as “Pro-Laser”, and the division was moved to the Advanced Manufacturing Park (AMP) in Sheffield, UK in 2007 so it could have more autonomy to innovate.

For for information: www.metlase.com

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