Modelling of workpiece temperatures for the dry milling of aluminium alloys

• Main Author: Richardson, David James
• Published: University of the West of England, Bristol 2007
• Subjects: 673.72235
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436903

The understanding of how temperatures are distributed in the machining process and the effect that they have on the workpiece material for different machining conditions is critical to successful dry milling of aluminium alloys. This research examines the amount of heat generated in the workpiece for the dry machining of aluminium alloys and measures the affect of this heat on the structural integrity of the material. An analytical peripheral milling thermal model has been developed. This was defined by the chip formation mechanisms occurring in peripheral milling and the geometry of contact between the cutting tool and workpiece. This model required cutting tool heat flux as an input. A cutting tool heat flux model was generated for a 7000 series aluminium alloy by using the peripheral milling thermal model in an inverse framework; with measured workpiece temperature results forming the input to the model. Workpiece temperatures were measured using embedded thermocouples in a fixture and the model was validated through extensive cutting tests. The research has demonstrated that for peripheral milling the local workpiece surface temperature rises are so low that they do not affect the surface integrity of the aluminium alloy workpiece. The thermal model illustrates that workpiece surface temperatures are low because the high temperatures generated in the shear zone are not transferred to the finished machined surface. The research has also established that local workpiece temperatures can be reduced by increasing surface cutting speeds or the feed per tooth, or by reducing the diameter of the cutting tool. The research has demonstrated that the proposed thermal model can represent temperature distributions in the workpiece for the peripheral milling of aluminium alloys for a wide range of cutting conditions and cutting speeds. The peripheral milling model was also implemented in an inverse framework over a wide range of cutting conditions to produce a cutting tool heat flux model for 7000 series aluminium alloy.