SBIR-STTR Award

This Small Business Innovation Research Phase I project, Modeling Tools for the Machining of Ceramic Matrix Composites (CMCs), will develop and demonstrate the feasibility of physics-based modeling tools applied to the machining of ceramic matrix composites (CMC) the Air Force needs to machine critical CMC turbine components faster, more accurately, and with lower cost. At the program conclusion, TWS will demonstrate modeling tools capable of identifying the salient process attributes that will result in a 35-50 percent reduction in machining cycle times while maintaining tool life and improving part quality. This will be achieved through the advancement and application of both a detailed-level finite element modeling (FEM) of the tool-workpiece interaction, as well as a toolpath-level analysis of entire part programs. The outputs of these comprehensive models – temperatures, residual stresses, forces, damage and power – combined with intelligent process optimization algorithms, will provide the ability to predict and manage cutting forces and tool wear while simultaneously reducing machining cost and cycle time and maintaining acceptable part quality. The validated models will take into account the heterogeneous, orthotropic nature of CMC composites through the use of fracture plane models capable of general representation of material toughness in complex orientations.

Benefits:
Existing CAM software tools generate toolpaths entirely based on the geometric aspects of machining, without consideration for the material properties or the process physics such as forces, deflections, etc. leading to a need for significant input from the manufacturing engineers in order to mitigate the above effects. Manufacturing engineers must rely on their machining knowledge and prior experience from related designs and materials. Where such knowledge is not available, the manufacturing engineer has to undergo significant trial-and-error testing to develop a robust process. These methods are expensive, time consuming, and often lead to suboptimal solutions since only a limited range of process alternatives can be explored. Lack of validated modeling tools necessary to understand the magnitude and nature of the machining forces on the final part, temperature and abrasive wear effects on the tool, or workpiece deflection on the final part geometry are significant factors that limit the ability to improve part quality and reduce costs. Similarly, the inability of current software tools such as CAM or verification systems to consider the workpiece material effects during toolpath generation poses additional barriers to rapid, optimal toolpath programming. The anticipated benefits of proposed CMC machining modeling programs: •A 35-50 percent reduction in the machining cycle times for Air Force CMC engine components •Development of both detailed-level (FEM) and toolpath-level machining models providing a comprehensive, multi-scale physics-based modeling capability •Demonstration of process improvements on a candidate Air Force component •Dramatic reduction in machining process set-up times via analysis and optimization off-line, in advance of manufacturing process implementation •Maximize capabilities of existing capital equipment through tooling and process improvements •Eliminate trial-and-error testing through the use of validated physics-based models •Improved tool life resulting from the judicious selection of tooling and process parameters as determined from detailed-level analysis •Generic models applicable to a wide variety of materials, machine tools and components throughout the DoD

Keywords:
physics-based modeling, CMC, composites, machining

This Small Business Innovation Research Phase II project, Machining Tools for the Machining of Ceramic Matrix Composites, will build on the Phase I feasibility demonstration of CMC machining simulation technology and will further develop, mature, demonstrate, and prepare for transition modeling tools resulting in cost-effective machining processes for fiber-reinforced ceramic matrix composites (CMCs). The technology innovations and augmentations of the proposed project will develop and demonstrate physics-based modeling and simulation methodologies to inform, shape and improve high-productivity machining processes of DoD mission-critical components. TWS will improve and validate the fundamental detailed-level modeling that is based on finite element simulation to inform the toolpath-level simulation software. Improving the fundamental understanding of the machining process of CMCs will allow for physics-based models to be used in toolpath simulation and optimization. In this project, TWS will develop process improvement strategies and will demonstrate improvements on candidate components. The benefits of using validated physics-based material-specific libraries for toolpath optimization include reduced costs and cycle time, improved quality of critical components and reduced scrap of high value-added parts.

Benefits:
CMC machining is more challenging than metal machining due in part to the relative immaturity of composite machining practices and the lack of industry familiarity. Generally, the challenges encountered in the CMC manufacturing industry are due to the nature of the materials, various aspects of the tooling used and sensitivity to process parameters. Existing CAM software tools generate toolpaths entirely based on geometrical aspects of machining, without consideration for the material properties of the process, physics, such as force, deflection, etc, leading to a need for significant input from manufacturing engineers in order to mitigate the above effects. This project aims to improve the machining aspect of fabrication through the development physics-based simulation tools. Anticipated benefits of the proposed project are: (a) development of both detailed-level (FEM) and toolpath-level machining models providing a consistent and comprehensive, multi-scale, physics-based modeling capability, (b) a 35 to 50 percent reduction in the machining cycle times for Air Force CMC engine components, (c) demonstration of process improvements, reduction in machining process set-up times via analysis and optimization off-line in advance of manufacturing process implementation, (d) maximizing production capabilities of existing capital equipment through tooling and process improvements, and (e) eliminating trial-and-error testing through the use of validated physics-based models.

Keywords:
CMC, composite, ceramic, machining, optimization, physics-based modeling