Investigation of tool deflection during milling of thread in Cr-Co dental implant

Abstract

Milling is a good option for manufacturing internal threads in hard-to-cut dental components due to lower cutting forces. In the case of a very small drilled diameter, the tool cannot be large enough to reduce tool deflection nor sufficiently small to avoid the influence of the tool penetration. As a consequence, both situations need to be considered and no other research study dealt with this aspect for the modeling of thread milling forces. This article deals with the analysis of forces, deflection, and undercutting during machining of one typical internal thread geometry used for implants in a chrome-cobalt dental alloy. The geometry is analyzed considering the influence of tool penetration and it is presented new equations to identify the regions where it occurs. Machining experiments are conducted acquiring cutting forces and tool axis position in order to calculate the tool radial forces and estimate tool deflection. Manufactured threads geometry is measured to evaluate dimension quality. It can be claimed that the tool trajectory should consider one extra revolution around the drilled hole in order to machine the undercut material due to tool deflection for this small tool diameter.

Integrated Design of Spindle Speed Modulation and Cutting Vibration Suppression Controls Using Disturbance Observer for Thread Milling

“…Therefore, some studies have focused on the effects of cutting force and cutting torque dynamics during thread milling. For example, Araujo and Fromentin [5] studied the relationship between the cutting forces and tool deflection in a typical internal thread machining and proposed a tool trajectory planning method for the hard-to-cut materials by considering the tool deflection characteristics. Sharma et al [6] studied the influence of tool geometry on the cutting forces and concluded that the cutting forces can be minimized by applying a proper penetration strategy for the cutting tool.…”

Analytical derivation of thread profile in internal thread milling process

“…Jun and Araujo 15 investigated the thread milling process by using a thrilling tool that can perform both drilling and thread milling operations. Araujo and Fromentin 16 used the thread milling process in the production of micro threaded holes (M2) for dental implants and stated that undercut material due to the tool deflection can be machined with extra pass. Khorasani et al 17 investigated the effect of cutting fluid pressure on the surface quality in the thread milling of two different workpieces and stated that the fluid pressure is an important parameter in achieving better surface quality.…”

Mathematical Model for Tapping Simulation to Predict Radial Pitch Diameter Difference of threads

“…Tapping is a process widely used in the manufacturing of internal threads. Although in the past few years, other processing methods have been used to manufacture internal threads with great success, such as thread milling and turning [11][12][13][14][15][16], tapping is almost the only method to manufacture small diameter internal threads [17]. However, there are relatively few literatures on thread quality in tapping.…”