Cutting force prediction for ball-end mills with non-horizontal and rotational cutting motions

Abstract

Accurate cutting force prediction is essential to precision machining operations as cutting force is a process variable that directly relates to machining quality and efficiency. This paper presents an improved mechanistic cutting force model for multi-axis ball-end milling. Multi-axis ballend milling is mainly used for sculptured surface machining where non-horizontal (upward and downward) and rotational cutting tool motions are common. Unlike the existing research studies, the present work attempts to explicitly consider the effect of the 3D cutting motions of the ballend mill on the cutting forces. The main feature of the present work is thus the proposed generalized concept of characterizing the undeformed chip thickness for 3D cutter movements. The proposed concept evaluates the undeformed chip thickness of an engaged cutting element in the principal normal direction of its 3D trochoidal trajectory. This concept is unique and it leads to the first cutting force model that specifically applies to non-horizontal and rotational cutting tool motions. The resulting cutting force model has been validated experimentally with extensive verification test cuts consisting of horizontal, non-horizontal, and rotational cutting motions of a ball-end mill.

Nonlinear Modeling and Dynamic Simulation Using Bifurcation and Stability Analyses of Regenerative Chatter of Ball-End Milling Process

“…The relationship between the cutting force and the chip thickness that was employed in the present study is represented by as follows [1]: 3 where d , ( , ) and d , ( , ) are the differential tangential and radial cutting force components of a cutting element, respectively; ( ) and ( ) are the cutting-mechanics parameters for horizontal cutting motions, which play a role in characterizing the local cutting mechanics of the differential cutting edge. Unlike the cylindrical end, the ball end of a ball-end mill is considered in the present model through these cutting-mechanics parameters ( and ), which vary along the tool axis ( -axis) and are generally determined from experimental data [1], and and are the exponents of the chip thickness, which explicitly characterize the size effect in metal cutting [4]. ( , ) is a screen function that is equal to 1 if the th cutting edge is in the cut; otherwise, it is equal to 0.…”

“…Furthermore, to determine the stability of ball-end milling systems, investigation of the cutting force effect is also required. Based on the relation between the cutting force and the uncut chip thickness in the ball-end milling process, two types of models are commonly used to predict the cutting forces: nonlinear models [1][2][3][4] and linear models [5][6][7][8][9]. Nonlinearity in the cutting force model is known to exist because of the size effect [10].…”

Cutting Force Modeling and Experimental Study for Ball-End Milling of Free-Form Surfaces

“…Tuysuz et al [19] proposed a mechanical model to predict the cutting force in three directions during the milling process of ballend cutters by simulating the chip thickness distribution, cutting, and indentation mechanics. Azeem et al [20] proposed a method for characterizing the thickness of undeformed chips in three-dimensional tool motion and improved the cutting force model for multiaxis ball-end milling. Zhang et al [21] proposed an accurate model of instantaneous undeformed chip thickness considering tool runout effect.…”

Enhancing surface integrity by high-speed extrusion machining

“…However, the continuous chip flow breaks down and serrated chips begin to form with the increasing cutting speed [5,6]. The chip morphology transition from continuous to serrated chips leads to the intense cutting force fluctuation [7][8][9][10], which is generally believed harmful for the cutting tool and surface integrity [11][12][13][14]. Therefore, the serrated chips should be suppressed in order to improve the surface integrity of machined components during HSM.…”