Aerospace Parts Machining Gains an "AdvantEdge"

  • Published
  • Materials and Manufacturing
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  While advances in the high-speed machining of aluminum materials have undeniably reduced the cost of aerospace structures, a recent breakthrough in the HSM of titanium (Ti) is likely to save the aerospace industry--and consequently, the Department of Defense--millions of dollars annually. Under Small Business Innovation Research contract to AFRL, Third Wave Systems, Inc., employed AdvantEdge FEM 3D, its finite-element software package dedicated to the three-dimensional modeling of materials and cutting conditions and cutting processes, to address the heat and temperature challenges known to hinder Ti cutting operations.

The machining characteristics of Ti make high metal removal rates difficult to achieve. This challenge is a major driver of machining costs in the production of Ti-based aerospace components. In pursuing higher productivity and lower finished-product cost, AFRL sought innovative concepts for improving metal removal rates and machining efficiencies. Much of the HSM process is fundamentally an issue of thermal management. Research indicates that the frequency of machining passes in relation to generated heat plays a key role in the resulting cutting forces. Because it is neither practical nor economical to measure temperatures during cutting operations--and given the substantial cost and time required for trial-and-error testing--process modeling emerged as the tool of choice.

Enter Third Wave Systems, which began work with the 2008 award of a SBIR Phase III contract geared towards the successful transition of modeling and HSM technologies to military applications for the efficient and affordable fabrication of Ti used in F135 and F136 engine components. Accordingly, the company used its computer-aided engineering software, AdvantEdge FEM 3D, to simulate a combination of HSM techniques and high-frequency tooth-pass machining methods, ultimately identifying optimal machining conditions for Ti. AdvantEdge FEM 3D enables users to bypass expensive trial-and-error testing while gaining additional insights not available for test data. The 3D simulation uses the STEP file import capability of the software with a CAD geometry, a combination permitting users to analyze the effect of cutting edge and surface geometries without conducting costly experimental testing. By varying the initial process parameters of the model, users can determine optimal cutting conditions via the standard AdvantEdge FEM 3D outputs of stress and temperature.

The software is also capable of producing drilling analysis, which is simulated based on cutting edge temperatures and stresses as indicators of tool wear.  Users can perform a drilling analysis of a twist drill breaking through a work piece, which yields temperature profiles and predicts chip formation. Further, the software can perform indexable milling analyses of chip formation and forces in materials. Benefiting commercial and military interests alike, AdvantEdge FEM 3D introduces the use of HSM techniques that, in addition to increasing Ti material removal rates and improving machine tool life, shorten product design cycles, reduce trial-and-error testing, and improve parts quality through residual stress prediction.