Surface Generation In Diamond Research Articles

A theoretical and experimental study of spindle imbalance induced forced vibration and its effect on surface generation in diamond turning

Abstract In diamond turning, spindle error motions exhibit dynamic characteristics under spindle imbalance, which significantly deteriorate form accuracy and surface roughness. However, in the spindle error motion community dynamic characteristics of spindle imbalance induced forced vibration have not attracted much attention, involving unbalanced magnetic forces induced forced spindle vibration, unbalanced air bearing pressure induced forced spindle vibration, and spindle whirling and spindle tilting under bearing hydrodynamics along with inertial effect. In this study, a theoretical and experimental investigation has been conducted to discuss dynamic characteristics of spindle imbalance induced forced vibration and its effect on surface generation in diamond turning. Firstly, an analysis model of magnetic forces for a spindle motor was built up to study dynamic characteristics of unbalanced magnetic forces induced forced spindle vibration. Secondly, a mathematical model of Reynolds equations for air bearings was established with a five-DOF dynamic model for spindle motion to discuss dynamic characteristics of unbalanced air bearing pressure induced forced spindle vibration, spindle whirling and spindle tilting. Finally, it has been verified by two kinds of designed face-turning tests for comparison carried out in diamond turning. The theoretical and experimental results revealed that bearing hydrodynamics coupled with inertial effect would jointly induce synchronous quasi-elliptical spindle whirling/tilting, accordingly producing a quasi-elliptical concave/convex surface in diamond turning, whose cyclic frequency is 2 rev.−1. Under spindle imbalance, unbalanced magnetic forces induced forced spindle vibration with the fundamental cyclic frequency of 2p rev.−1 (the spindle motor pole number) would occur as well as unbalanced air bearing pressure induced forced spindle vibration with the cyclic frequency of α rev.−1 (the air bearing orifice number) further to produce the corresponding straight radial patterns at the machined surface. This research work gives a deep insight into dynamic characteristics of spindle imbalance induced forced vibration and its effect on surface generation in diamond turning.

Surface Characterization in Diamond Turning of Highly Anisotropy Brittle Crystals: A Multi-Spectrum Analysis Approach

This paper presents a multi-spectrum analysis method for the characterization of the surface generation in single-point turning of brittle single crystals. The features on the diamond turned surfaces were extracted and analysed by the power spectrum analysis of the surface roughness profiles measured at a number radial sections of the workpiece. By the analysis of the variation of the spectral patterns in the multi-spectrum plots, the surface roughness and materials effect on surface generation are found to be strongly related to the power spectrum. This provides an important means to explain quantitatively the effect of factors affecting the surface generation in diamond turning brittle crystals.

Effect of reinforcement in ultra-precision machining of Al6061/SiC metal matrix composites

The effect of reinforcement on surface generation in diamond turning of Al/SiC metal matrix composites is investigated. The surface generation is affected by the cut through and pulled out mechanisms in cutting the reinforcement. Better surface finish can be achieved with the use of whisker reinforcement and smaller volume fraction of SiC reinforcement.

A theoretical and experimental investigation of surface generation in diamond turning of an Al6061/SiC p metal matrix composite

In this paper, the surface generation in ultra-precision diamond turning of Al6061/15SiC p metal-matrix composites was investigated based on different analytical approaches which include parametric analysis, cutting mechanic analysis, finite element method (FEM) analysis and power spectrum analysis. Parametric analysis was performed to explore the in situ inter-relationships between the process parameters and the surface roughness. The surface properties of the diamond turned surface were extracted and analyzed by the power spectrum analysis of the surface roughness profiles. Different surface generation mechanisms were deduced based on the cutting mechanics and FEM analysis. The results of the theoretical analyses were verified through a series of cutting tests conducted under various cutting conditions and a good correlation between the theoretical and experimental results was obtained.