Shunmugam M S

The functional behaviour of manufactured surfaces is influenced by the surface topography. Encouraged by the results obtained in the implementation of two-dimensional motifs for practical profiles, a few attempts have been made to arrive at areal motifs for characterization of the surfaces. In this paper, an approach for establishing three-dimensional motifs based on triangular motif is presented. The triangular motif is formed with three peaks and a deep valley between them. To represent the surface by significant motifs, initial motifs are combined using four rules that are extended from the rules defined in ISO 12085 for combining two-dimensional motifs. Application of this technique to practical surfaces shows interesting results for characterizing the manufactured surfaces. © IMechE 2005.

Sensing Acoustic Emission (AE) signals from a machining process is one of the most promising methods suitable for tool condition monitoring because of its sensitivity combined with quick and high frequency response. In this work, AE signals are monitored during rough, finish and plateau honing of cylinder liner using fresh and completely worn out honing tools. AE parameters such as Root Mean Square (RMS), peak to peak, skewness and kurtosis and dominant frequency in the power spectrum are analysed. The results show that the dominant frequency in the power spectrum is very sensitive to honing tool conditions and a good correlation exists with honed surface quality. Therefore, AE signals can be used for ascertaining the honing tool performance and establishing the end of tool life. Copyright © 2008, Inderscience Publishers.

Surface roughness and cutting velocity are considered as critical machining performance measures in Wire-Electro Discharge Machining (WEDM). In this presentation the results of experiment conducted on 5-axis CNC-WEDM machine on a Ti-6Al-4V alloy will be highlighted. The different setting parameters available on the machine are machining voltage, ignition pulse current, pulse duration, time between two pulses, maximum servo speed variation, servo-control reference voltage, wire speed, wire tension and injection pressure. Many levels of the input variables or parameters must be considered to understand their influence on performance. However, all parameters do not have same degree of influence. Thus experiments are conducted in accordance with Taguchi's L18 Orthogonal Array using three levels to predict the influencing parameters by analysis of variance (ANOVA). Six parameters are identified and experiments are conducted at five different levels for each parameter. The results, findings and observations will be highlighted in this presentation.

Using a line segment or circle as a structuring element, morphological operations have been carried out on surface profiles for filtering purposes. This paper brings out a new method of filtering surfaces with a combination of morphological operations using a 3D-structuring element, namely a toroid. A strategy to select appropriate radii for the structuring element depending on surface amplitudes and required amount of waviness separation is also proposed. The proposed filtering method is compared with envelope and closing filters which are also based on the concepts of morphological operations. An analysis of waviness transmission, distortion of roughness surface and effect of deep grooves on a reference surface is presented to bring out the advantages of the proposed method. Few examples of filtering of practical surfaces using the proposed method are also included to bring out the nature of the reference surfaces obtained. © 2006 IOP Publishing Ltd.

This paper presents a novel method, based on the particle impact damping (PID), for the attenuation of regenerative vibration in boring operation. A specially designed boring bar having a cavity near machining-end for partial filling of spherical particles has been developed. Characteristics of boring bar with and without PID have been found from impact and shaker tests. After identifying appropriate particle size and filling volume, experiments are conducted to evaluate the performance in actual boring operations. Additional boring experiments are also conducted to confirm the performance by changing particle size and filling volumes. The collision of the particles in PID is found to attenuate regenerative vibration by the energy dissipation and thus effectively enhances stability of the boring operation. Analysis of effect of PID on surface topography in terms of chatter marks, surface roughness, and roundness of bored holes shows that the proposed method results in improvement of bore quality when compared with a boring bar without PID. It is also established that radial vibration of the boring bar has a significant influence on the surface topography obtained in boring operation.

Surface topography of cylinder liners influences the functional behaviour of internal combustion engines. The cylinder liners after boring operation are subjected to rough, finish and plateau honing operations in which parameters such as rotary speed, reciprocating speed, pressure and honing time are selected on the basis of operator's experience. The present work is a comprehensive investigation carried out to identify the significant honing parameters and their values for different honing operations. The honing trials are carried out according to design of experiments. Before each operation, all cylinder liners are processed identically under conditions identified from the previous operation. Parameters considered for characterising the surface topography are roughness average (Ra) and all five bearing area parameters (Rpk, Rk, Rvk, Mr1 and Mr2). It is established in the present work that Ra can be replaced effectively by Rk in finish and plateau honing operations to control the final surface topography and these parameters (Ra, Rk) are influenced by honing pressure. For the most important bearing area parameter Mr2, the significant process parameters are medium honing time in finish honing and high reciprocating speed in plateau honing. These results are useful for controlling the honing operations during the manufacture of the cylinder liners. Copyright © 2009, Inderscience Publishers.

Among different filtering approaches used to remove waviness and obtain roughness, envelope and motif techniques are considered to be suitable for functional characterization. Morphological filtering being closely related to envelope technique can be used for filtering of surfaces. This paper discusses a new approach combining morphological operations namely closing and opening with circle as structuring element in a unique way to generate the reference profile representing waviness. The reference profile generated by this method is smooth without any slope discontinuities and robust against deep valleys present in the profile. Analysis of the proposed method for robustness and form-approximation capabilities is presented in this paper. Comparison is also made with envelope and morphological closing filters as well as Gaussian regression filter to bring out the effectiveness of this approach. © 2005 Elsevier Ltd. All rights reserved.

Establishing a reference profile representing wavelength components of waviness and form of measured surface profile is an important step in surface metrology. This paper describes a new method of fitting a reference profile by taking a combination of sinusoidal functions and a second degree polynomial using least absolute deviations (LAD) criterion. The reference profile so obtained is found to exhibit form approximation capability and robustness against outliers such as deep valleys in the surface profile. Few examples of practical and simulated surface profiles are taken to bring out the nature of the reference profiles and a comparison with robust Gaussian regression filtering method is also presented to show the effectiveness of the proposed fitting scheme in separating waviness and form.

Mechanical polishing is a finishing process practiced conventionally to enhance quality of surface. Surface finish is improved by mechanical cutting action of abrasive particles on work surface. Polishing is complex in nature and research efforts have been focused on understanding the polishing mechanism. Study of changes in profile is a useful method of understanding behavior of the polishing process. Such a study requires tracing same profile at regular process intervals, which is a tedious job. An innovative relocation technique is followed in the present work to study profile changes during mechanical polishing of austenitic stainless steel specimen. Using special locating fixture, micro-indentation mark and cross-correlation technique, the same profile is traced at certain process intervals. Comparison of different parameters of profiles shows the manner in which metal removal takes place in the polishing process. Mass removal during process estimated by the same relocation technique is checked with that obtained using weight measurement. The proposed approach can be extended to other micro/nano finishing processes and favorable process conditions can be identified.