NAS (National Aerospace Standard) 979 is the only standard well known in industry describing a five-axis machining test for measuring kinematic errors of five-axis machine tools. As it cannot reflect the tool path characteristics of typical ruled surface machining, five-axis machine tools which passed the NAS test may not have the ability to satisfy the requirement of the real industrial applications. To fill this gap between the NAS test and the real industrial applications, an “S” machining test is proposed in this paper. The case study shows that the proposed machining test is feasible and practicable.

A regularization homotopy iterative method established for ill-posed nonlinear least squares problem. Two new regularization parameter selecting strategies are proposed, which are called direct search method and interval division method. The calculation results of nonlinear least squares problems show that the regularization homotopy iterative method and parameter selecting strategies proposed in this paper are correctly and applicable. And also calculation results of nonlinear adjustment of free networks with rank deficiency of Jianglong bridge pier displacement defor-mation monitoring control network show that the method not only decrease the iterative matrix con-dition number, but also make the condition number small fluctuation in full iterative process.

With the development of modern aircraft, complex titanium alloy aircraft structural parts are widely used. As a kind of difficult machining material, it’s easy to burn the tools and the parts during machining the titanium alloy structural parts because of the gathering heat. The article studies the technology to prevent burning the titanium structural parts during the machining process. The burnt problem can be effectively solved by using proper tools, proper machining parameters and fully cooling environment.

Multi-axis CNC machining shows great advantages in manufacturing parts with geometries being defined by complex surfaces. NURBS (Non-Uniform Rational B-Spline) interpolation and polynomial interpolation are two new types of interpolation to improve productivity. Compared to the NURBS interpolation, the polynomial interpolation can gain higher productivity. However, no commercial software tool is available to generate polynomial interpolation CNC programs. This paper proposes a postprocessor to generate polynomial interpolation multi-axis CNC program. A case study with simulations demonstrated that the polynomial interpolation program generated by the proposed postprocessor has higher machining efficiency than liner interpolation and NURBS interpolation program.

The titanium alloy thin-walled parts with rotary structure are often used as the elements for positioning, connecting and load bearing in aerospace field. However, tool wear will appear in the precision turning of such parts by using cemented carbide tools or diamond tools, and the machining accuracy deteriorates. On basis of the study on machining features of titanium alloy thin-walled parts with rotary structure, the cutting error is corrected for tool wear by online compensation, and the machining deformation caused by cutting force is controlled by using diamond turning with ultrasonic vibration in this paper. The elliptical ultrasonic turning is used to machining a typical spaceborne titanium alloy thin-walled cylinder with minimum wall thickness of 3mm, and the roundness error is controlled to 2.83μm for the machined inner hole. The requirement is satisfied on shape accuracy, and the machining feasibility is proved.