Controlling deformations of thin-walled Al 6061-T6 components by adaptive clamping

Abstract

High strength, light weight, thin-walled components are gaining in importance with good market growth potential in key industries like aerospace, automotive, power generation, medical technology, etc. The challenges in machining thin-walled workpieces include static workpiece displacements and large deformations caused by local indentations at contacts and higher structural compliance, respectively. The chosen machining strategy is crucial to obtain good surface finish and fine control over dimensions and form. Owing to the limited applicability of analytical methods to standard workpiece geometries, a finite element method based numerical framework is developed in ANSYS for predicting contact and structural deformations that suits all workpiece geometries and boundary conditions. The numerical results are validated by experimental measurements using CNC-CMM on Aluminium 6061-T6 workpiece located in 3-2-1 milling fixture with two hydraulic clamps having adjustable clamping pressure. The results of static deformations match within 20%. Subsequently, clamping force-deformation characteristics are plotted for implementing corrective clamping mechanism to control workpiece deformations. This methodology will be integrated with the Computer Aided Fixture Design (CAFD) System to realize design of adaptive clamping fixtures, thereby, reducing rejections and increasing quality and productivity.