An accurate instantaneous uncut chip thickness model combining runout effect in micro-milling using cutters with the non-uniform helix and pitch angles

Abstract

As a key factor, the accuracy of the instantaneous undeformed thickness model determines the force-predicting precision and further affects workpiece machining precision in the micro-milling process. The runout with five parameters affects the machining process more significantly compared with macro-milling. Furthermore, modern industry uses cutters with non-uniform pitch and helix angles more and more common for their excellent properties. In this article, an instantaneous undeformed thickness model is presented regarding cutter runout, variable pitch, and helix angles in the micro-milling process. The cutter edge with the cutter runout effect is modeled. Then, the intersecting ellipse between the plane vertical to the spindle axis and the cutter surface which is a cylinder can be gained. Based on this, the points, which are used to remove the material, on the ellipse as well as cutter edges are calculated. The true trochoid trajectory for each cutting point along the tool path is built. Finally, the instantaneous undeformed thickness values are computed using a numerical algorithm. In addition, this article analyzes runout parameters’ effects on the instantaneous undeformed thickness values. After that, helix and pitch angles’ effects on the instantaneous undeformed thickness are studied. Ultimately, the last section verifies the correctness and validity of the instantaneous undeformed thickness model based on the experiment conducted in the literature.

Precision micro-milling process: state of the art

“…Although their work only considered conventional machining, much of what was learned could also be applied to micro-milling, with the effect becoming even more significant at the microdomain. Guo et al [ 104 ] then presented an instantaneous UCT model regarding tool runout and tool geometry in micro-milling. Using their early work as a foundation, they determined that five parameters were necessary to characterize tool runout in micro-milling, namely, runout offset length, inclination angle, cutter axis length, location angle, and initial rotation angle.…”

Micro milling force prediction of arc thin-walled parts considering dual flexibility coupling deformation

“…However, as an important factor affecting the milling force during arc milling, the actual instantaneous uncut thickness has not been taken seriously in these studies. In these studies, many experts and scholars have proposed new methods for determining the instantaneous uncut thickness and established models for various milling forces [7,8], yet the problem of arc milling has been simplified into a linear milling process.…”

Mechanistic model and probability characteristics of micro-milling force with a new parameter identification method

“…Wang et al 5 redefined and calculated the cutting radius and instantaneous uncut chip thickness in the machining process to predict the cutting force in the micro end milling process. Further, Guo et al 6 proposed an instantaneous undeformed thickness model for micro-milling considering tool runout, variable pitch, and helix angle. Based on multi-scale modeling and analysis, Niu and Cheng 7 proposed an innovative expression of micro machining cutting force.…”