Current Research

Machining Process Monitoring on Superalloys 

Principal Investigators: 

Sponsors:

General Electric Energy
Okuma USA 

Brief Abstract:

Superalloys are a relatively new class of materials which exhibits high mechanical strength, ductility, creep resistance at high operating temperatures, high fatigue strength, and typically superior resistance to corrosion and oxidation even at elevated temperatures. These properties make superalloys ideal for applications in aircraft, cryogenic tanks, submarines, nuclear reactors, and petrochemical equipment. In the aerospace industry, the most common superalloy used is the nickel-base alloy and it accounts for 30-50% of the total material required in the manufacturing of the aircraft engine, being used for rotating parts of gas turbines such as blades and disks, engine mounts, turbine casing and components for rocket motor and pumps. The primary objective of this project is to identify critical aspects in machining superalloy and develop a testing procedure for simulating the conditions found in the actual milling tests on superalloys and for monitoring in-process and post-process parameters. The experimental results will be further use to develop a machining process capable of controlling and identifying tool wear, and identifying the onset of subsurface damage and controlling its formation during processing. To accomplish this, a unified thermo/mechanical/plastic model relating process characteristics and cutting parameters need to be developed. The enhanced model parameters will be estimated in real-time on an open architecture machine tool. The adaptive model will then be employed in designing a multi-pass machining controller that will be capable of controlling process results such as geometry, deformation and tool wear. During the course of this research, the closed-loop machining system will be designed, implemented and validated on next generation open architecture machine tools. This will provide new insights into machining nickel-base alloys, but can also contribute to making full use of other advanced superalloys.

Impact:

This work will implement a methodology for studying the machinability of an advanced material, and for monitoring and controlling the process parameters for optimal surface quality and minimal subsurface damage with lower production cost. Thus the results of the project will be applied by industry. Furthermore, this research work will advance the understanding of fundamental aspects of machining superalloys and will be a good contribution to the science of manufacturing.

Project Schedule:

2009 to 2010

Publications:

1.  A.J. Henderson, M. Gall, C. Bunget, and T.R. Kurfess - ‘Machining process monitoring on superalloys (nickel-base alloys)', Report No. CUICAR/GE, 2009.
2. A.J. Henderson, C. Bunget, and T.R. Kurfess - ‘Cutting forces modeling when milling nickel-base superalloys', submitted to MSEC 2010.
3. B.J. Richardson, C. Bunget, and T.R. Kurfess - ‘A statistically based determination of the depth of the machining affected zone in nickel-based superalloys using Matlab', submitted to MSEC 2010.

Preliminary Results:
The approach and methodology for this research is illustrated in Figure 1. The work involves linking various milling parameters and in and post process measurements to subsurface damage. This work will start with existing process parameters (currently used in production), and incorporate in process and post process measurements of cutting forces and power consumption, material deformation, optical microscopy, light interferometry and scanning electron microscopy.

 

Figure 1: Flowchart representation of the approach and methodology of the research.