Effect of vibrations on the residual stress field formation during milling of high-strength aluminum alloys

The authors examine the influence of high-speed milling on the distribution of residual stresses in parts made of structural high-strength aluminum alloys Al-Cu-Mg, which are the main structural materials in the aerospace industry. Milling was carried out at high cutting speeds. Different tool settings were used to balance the instrument. Plastic deformation occurred in the part’s surface layers. Residual stresses were measured by the X-ray method. It was found that high-speed milling creates residual compressive stresses that are favorable for the operation of the part. The depth of the residual stresses depends on the cutting mode. The article shows the relationship between residual stresses and the type of metalworking tool, processing conditions in structural parts made of high-strength aluminum alloys.

Optimizing the High-Performance Milling of Thin Aluminum Alloy Plates Using the Taguchi Method

Most aerospace parts are thin walled and made of aluminum or titanium alloy that is machined to the required shape and dimensions. Deformation is a common issue. Although the reduced cutting forces used in high-speed milling generate low residual stress, the problem of deformation cannot be completely resolved. In this work, we emphasized that choosing the correct cutting parameters and machining techniques could increase the cutting performance and surface quality and reduce the deformation of thin plates. In this study, a part made of a thin 6061 aluminum alloy plate was machined by high-speed milling (HSM), and a Taguchi L16 orthogonal array was used to optimize the following parameters: linear velocity, feed per tooth, cutting depth, cutting width, and toolpath. The impact of cutting parameters on the degree of deformation, surface roughness, as well as the cutting force on the thin plate were all investigated. The results showed that the experimental parameters for the optimal degree of deformation were A1 (linear velocity 450 mm/min), B1 (feed per tooth 0.06 mm/tooth), C1 (cutting depth 0.3 mm), D4 (cutting width 70%), and E4 (rough zigzag). Feed per tooth was the most significant control factor, with a contribution as high as 63.5%. It should also be mentioned that, according to the factor response of deformation, there was a lower value of feed per tooth and less deformation. Furthermore, the feed per tooth and the cutting depth decreased and the surface roughness increased. The cutting force rose or fell with an increase or decrease of cutting depth.

Analysis of Cutting Forces From Conventional to High-Speed Milling with Straight and Helical-Flute Tools for Flat-End Milling Incorporating the Effect of Tool Runout

This paper presents a systematic study to analyze the dependence of cutting forces on tool geometry, workpiece material and cutting parameters such as spindle speed, tool engagement and cutting direction in flat-end milling with tool runout. The cutting forces are determined according to a mechanistic force model considering the trochoidal flute path to calculate the undeformed chip thickness, and average cutting force and linear regression model are applied for identifying the coefficients of the force model. A series of milling processes are conducted on AZ31 Magnesium (Mg) alloy and titanium alloy (Ti6Al4V) to analyze the instantaneous cutting force curves, amplitudes of cutting forces and peak forces over a wide range of spindle speeds from conventional to high-speed milling. It is demonstrated that the values of the cutting force coefficients are higher at conventional spindle speed and decrease with an increase in spindle speed, especially when machining Ti6Al4V alloy. For the edge force coefficients, it is observed a slight variation when using cutting tools with different helix angles. Besides, the cutting force amplitudes strongly depend upon the workpiece material. The helix angle has a significant influence on the transverse force amplitude at conventional speed. The forces obtained mechanistically are also substantiated by comparison with measurements.