Microturning of landing gear components used in miniature unmanned aircraft vehicles

Abstract

The microturning of landing gear components used in miniature unmanned aircraft vehicles is described in this article. The finite element method (FEM) is used to predict variables such as microturning forces and temperatures at two different levels of roughing cut (1 and 3 mm depth of cut) with variable geometry cutting tool inserts. The predicted results are compared to experimentally determined magnitudes of forces and temperatures using a dynamometer and an infrared thermal camera. The results show that tool inserts with novel chip breaker functions reduce the magnitude of the machining forces and temperatures predicted using the FEM and validated by performing controlled experiments using Al-380 aluminum alloys machined with polycrystalline diamond-coated cutting tool inserts.

Similarity and difference in machining at mixed scales using nanostructured coated tools milling hypoeutectoid carbon steel

“…The internal force array of the elements is normalRnormalinormalanormalinormalnnormalt=false∫BOnormalPnormali,normaljnormalNnormala,normaljnormaldnormalVnormalo, where N a,j denotes shape functions of repeated indices, the comma representing a partial differentiation with respect to spatial coordinate(s), and P i,j is the nominal “Piola-Kirchhoff” stress tensor for the matrix of elements. 10, 11…”

“…The camera was connected to the computer through a composite video card, while an Osprey capture card was used to freeze dynamic thermal images. 10 The camera was directed at the tip of the cutting tool and the maximum temperature was recorded during machining experiments.…”

“…For micromilling, the A, D, E, and F criteria have not normally been calculated or measured. However, Jackson et al 10, 11 conducted experiments to begin characterizing similarity measures in micromilling. When micromachining aluminum alloys with 1–3 mm depth(s) of cut, Jackson et al 10, 11 noted that the A-criterion ~40–101, D-criterion ~0.3, E-criterion ~1.4–2.67, and F-criterion ~20–454 for coated and uncoated tools.…”

“…The following sections describe the calculation of forces and temperatures in micromilling of AISI SAE 1020 hypoeutectoid steel (~0.2 wt.% carbon in iron) using methods described in references. 10–12, 22, 24, 28, 29…”

“…However, during micromachining, the feed per tooth is equal to or less than the cutting edge radius (f tooth ≤ r c ). 10 Conventional milling tools are designed with slenderness ratios (l/d ~ 2–3), which prevents bending, whereas microtools are susceptible to bending because their diameters are only a few hundred microns. 11 During macroscale cutting, the leading tool edge encounters bulk material (composite structures), and therefore, avoids contact with hard particles, while a microcutting edge encounters individual grains ensuring contact with soft and hard particles.…”