Chip Flow and Scaling Laws in High Speed Metal Cutting

Abstract

Chip formation in machining plays an important role in the cutting process optimisation.Chip morphology often reflects the choice of cutting conditions, the tool wear and by consequences the integrity of the machined surface and tool life. In this study, photographs of the chip morphology during high speed machining of a middle hard steel (C20 similar to AISI1020} are taken by using a ballistic setup. From these recordings, the evolution of the chip morphology is presented and analysed in terms of cutting conditions. A simplified modeling is then proposed by considering the workpiece material as elastic perfectly plastic. The existence of a scaling taw governing the chip morphology in high speed machining is demonstrated. The cutting velocity is shown to have a weak effect at high speed machining as opposed to the well known strong influence of the velocity in the range of low cutting speeds.

Analysis of the Displacement of Thin-Walled Workpiece Using a High-Speed Camera during Peripheral Milling of Aluminum Alloys

“…In the study [ 23 ], a high-speed camera was used to analyze the morphology of chip formation in the cutting process, the study was additionally confirmed with an analytical model and an inconsiderable influence of the cutting speed change on the geometric features of the chip. On the other hand, Guo et al [ 24 ] presented a method of using a high-speed camera to analyze the dynamics of flow, deformation fields and chip formation in the process of sliding and cutting H02 bronze.…”

State-dependent distributed-delay model of orthogonal cutting

“…According to measurements reported in [24,42,44,39], this ratio is in the range 2 < A < 20 depending on the workpiece material (e.g. A ≈ 5 for steel, A ≈ 10 for copper in [42], and A ≈ 20 for aluminum in [24]).…”

“…Whereas τ is the regenerative delay, which is now equal to the rotation period and can be expressed with the angular velocity Ω of the workpiece: τ = 2π/Ω. Experiments show [24,39] that the chip thicknessh(t, θ) along the rake face (also called the deformed chip thickness) is proportional to the shifted uncut chip thickness h(t + θ) (also called undeformed chip thickness):h(t, θ) = Ch(t + θ), where 1 < C < 10 is a constant depending primarily on the workpiece material and the rake angle. Thus,…”

“…Now we improve his model by recognizing that the size l of the chip-tool interface is not constant, but is a function of the time-varying uncut chip thickness h. According to experimental results presented in [24,42,44,39], the relation between the contact length and chip thickness can be described using a linear (or shifted linear) function in a wide range of uncut chip thickness values. Therefore, we assume that the contact length is proportional to the uncut chip thickness at the tool tip:…”

“…According to experiments [24,42,44,39], the length and the shape of the force distribution depends on the chip thickness, which implies that the corresponding distributed delay in the model equation is state-dependent. The scope of this paper is to explore whether this state-dependent delay affects the linear and the global stability properties of the machining operation compared to the same model with distributed delay of constant length.…”