IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A generalized algorithm is presented in this paper to establish the reference figures as specified in the international and national standards on form errors. This algorithm is guaranteed to give optimal results and is well suited for implementation on a computer-interfaced, form-measuring instrument or a coordinate measuring machine. © 1991.

Department of Mechanical Engineering

Journal of Manufacturing Systems

Establishing reference figures for form evaluation of engineering surfaces

This paper deals briefly with the concept of form measurement and brings out the different criteria for form evaluation of engineering surfaces. A new criterion based on the minimum average deviation has been suggested. The geometrical forms, namely straight line, circle, plane, and cylinder, are analyzed. Simple numerical examples are included in this paper to illustrate the different methods.

Journal of engineering for industry

Criteria for computer-aided form evaluation

Reaming is carried out after twist drilling to enlarge and finish the holes accurately. The experiments were carried out on mild-steel workpieces at different reaming conditions and the accuracy and surface finish values are very briefly compared with the results of earlier investigators. A detailed analysis of the harmonic contents of the axial and transverse profiles of the reamed holes was carried out to bring out the process characteristics. A preliminary study of the cutting forces in reaming based on the spectral analysis is also reported. © 1990 Taylor &amp; Francis Group, LLC.

International Journal of Production Research

Investigations into reaming processes using a frequency-decomposition technique

Certain engineering components have half-bore and large-bore features whose dimensions have to be critically controlled during manufacture. The present work deals with the measurement details systematically and brings out the characteristics of these measurements. The descriptions of the measuring devices are also included. © 1989.

Precision Engineering

Measurement of half-bore and large-bore features

Gear shaping cutters are provided with top-relief and rake angles to facilitate effective cutting. Due to this, the profile representing the cutting edge (effective profile) is altered. This paper outlines a method of obtaining the effective profile and its deviations from the theoretical involute form required. This paper also deals with a method that modifies the pressure angle, while maintaining zero deviation at the reference circle, so that the effective profile closer to the theoretical form is obtained after grinding the rake face. The Golden section optimization method is used to get the optimum value of the modified pressure angle. The effect of regrinding on the profile error of the cutting edge is also brought out. The method suggested in this paper will be useful to the designers and manufacturers of gear shaping cutters. © 1988, All rights reserved.

International Journal of Machine Tools and Manufacture

Minimisation of error on the effective profile of pinion type gear shaping cutters

In gear generation processes, the involute profile of the gear is obtained as an envelope of the successive cuts made by the flank of the generating tool. The irregularities of the profile thus generated limit the quality of the gear. This paper reports the minimum achievable quality based on the maximum theoretical height of the irregularity for the involute spur gears. © 1988, All rights reserved.

Minimum achievable quality of involute gears in generation processes

Boring Trepanning Association (BTA) drills are capable of machining holes having a large length-to-diameter ratio in a single pass. This is a unique self-piloted operation in which cutting and burnishing are both carried out at the same time. Wear studies on BTA drills reveal quite useful information regarding their life and performance. This paper deals with wear studies on 20 mm diameter BTA drills (solid boring) of the Heller design using En9 steel work samples. The studies include examination of the flank and crater wear on the cutting edge, circular land wear and the supporting pad wear. The variation in wear with respect to cutting time for different speeds and feeds is reported. © 1988.

GENERAL

Wear

Wear studies in Boring Trepanning Association drilling

For functional reasons, the relationships between geometrical features of engineering components must be specified and controlled during manufacture, as must their geometrical form. This paper describes the concepts involved in the measurement and evaluation of geometrical relationships and explains the application of the least-squares technique with simple numerical examples. © 1988.

Assessment of errors in geometrical relationships

Form errors of engineering components are usually evaluated using linear deviations, although sometimes, normal deviations are also considered. This paper compares linear and normal deviations, using least squares and minimum deviation techniques. © 1987.

Comparison of linear and normal deviations of forms of engineering surfaces

Manufactured features generally deviate in size, form and relations with respect to other features from the features desired by the designer. Designers specify certain limits for these deviations that depend on functional requirements. The specification of different form errors is dealt with by the International Organization for Standardization (ISO). ISO also specifies that an ideal geometric feature must be established from the actual measurements such that the maximum deviation between it and the actual feature concerned is the least possible value. In practice, the least squares (LS) method is sometimes used for establishing the ideal feature, as this method is based on sound mathematical principles. However, the least squares procedure does not yield a minimum value. Therefore some attempts have been made to arrive at a form error based on the minimum deviation (MD) principles. A stray peak or valley on the actual feature introduces considerable variation in the results obtained by the minimum deviation method. This paper suggests a new approach based on the minimum average deviation (MAD). In this method, the ideal feature is established by using a search technique for different geometric features such as straight lines, circles, planes, cylinders and spheres. Using simple numerical examples, the values obtained by this approach are compared with the values obtained by the least squares and minimum deviation methods. © 1987.

Computer-Aided Design

New approach for evaluating form errors of engineering surfaces

B.T.A. drills are capable of machining holes having a large length to diameter ratio in a single pass to a higher degree of accuracy and surface finish. This is a unique self piloted operation in which cutting and burnishing are carried out at the same time. The accuracy of the hole in the axial as well as transverse sections is controlled by such a unique operation. In this paper, a complete profile analysis has been carried out in the axial and transverse directions. The results throw more light on the process characteristics and these are useful in the control of the process. © 1987.

Analysis of axial and transverse profiles of holes obtained in B.T.A. machining

In centreless through feed grinding the quality of the ground parts is influenced by several process variables. Some of these process parameters alter the frictional conditions at the control wheel-workpiece and the grinding wheel-workpiece interfaces which, in turn, influence the axial feed rate and rate of rotation of the workpiece. In addition, the type of cutting fluid plays an important role in determining the friction at the control wheelworkpiece interface. In this paper, an attempt is made to describe the influence of some of the process parameters on the slip in the axial movement and the change in the rate of rotation of the workpiece. Also the influence of different cutting fluids, which alters the nature of the frictional contact at the control wheel-workpiece interface, on the workpiece movements and quality of the ground parts is described. The experimental work carried out, in connection with this, is included. Further, from the analysis of the experimental results some useful conclusions have been derived which would be helpful in improving the performance of the process. © 1987.

Frictional behaviour and its influence on quality in centreless grinding

Centreless grinding is carried out with workpiece centre above the line joining the centres ofgrinding and control wheels. When a workpiece has a slight bend or a projection on the surface, it is safer to grind below the centres. This paper analyses the process of grinding above and below the centres. The results show that the roundness error increases only by a few microns when ground below the centres and the change in the surface finish is insignificant. © 1987 Pergamon Journals Ltd.

World University root node

Influence of workpiece position on roundness error and surface finish in centreless grinding

The grinding action and the rounding mechanism are highly complex in centreless grinding. The axis of the workpiece not only moves laterally but also tilts during the grinding process. Rowe and Barash have developed a two-dimensional model for an infeed centreless grinding neglecting the tilt of the workpiece. In this paper, an attempt has been made to develop a simulation model which incorporates the tilt of the workpiece. The theoretical and experimental investigations have been carried out with workpieces having specific geometries and the results are discussed. © 1987, Institution of Mechanical Engineers. All rights reserved.

Fulltext

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Three-dimensional geometric analysis of the plunge centreless grinding process

Selection of optimum setting in centreless grinding is based on the roundness error obtained. However, the roundness profile can be characterized in many ways, including mean line average height and harmonic analysis. In this paper, an approach based on a detailed analysis of the roundness profile is suggested. Theoretical and experimental results are presented. © 1987.

Optimizing workpiece position in centreless grinding by roundness profile analysis

Boring Trepanning Association (BTA) drills are capable of machining holes, having large length-to-diameter ratios, in a single pass. This is a unique self-piloted operation in which cutting and burnishing are carried out at the same time. A study of surface integrity, which comprises surface topography and subsurface metallurgy on machined and burnished layers of the work sample in BTA drilling, would reveal quite useful information regarding the performance of BTA drills. Surface integrity is also useful in understanding the functional behaviour of the manufactured part, namely wear, friction etc. This paper deals with surface integrity studies on En - 9 steel samples machined using a BTA drill under different machining conditions. The study includes the analysis of scanning electron micrographs, surface profiles and the variations in microhardness and residual stress on machined and burnished layers with different machining conditions. © 1987.

Investigations into surface topography, microhardness and residual stress in Boring Trepanning Association machining

The height and spacing characteristics of the surface profile influence the functional behaviour of the manufactured part. A new method known as motif combination has been recommended in French standards to obtain the height and spacing characteristics of the surface profiles. An attempt has been made in this paper to compare motif combination techniques with the mean line and envelope systems, taking practical profiles. © 1987.

Comparison of motif combination with mean line and envelope systems used for surface profile analysis

Selection of optimum conditions in centreless grinding is based on the roundness error and surface finish which are post-process measurements. In-process measurement of the roundness error and surface finish, because of its complexity, has hardly been attempted in centreless grinding. But monitoring of some of the process parameters during grinding can be done to control the quality of the ground parts. In this paper, the influence of some of the process parameters on the quality of the ground parts is brought out and how monitoring of these parameters can lead to the optimum conditions is discussed. Experimental work carried out in this connection is reported.

PROCESS MONITORING IN CENTRELESS GRINDING FOR OUT-OF-ROUNDNESS AND SURFACE FINISH CRITERIA.

The geometrical features of the engineering components should maintain good form accuracy and proper relationship among them. This paper discusses the problems encountered in the measurement of relationship and explains the application of least squares technique with simple numerical examples. Evaluation of different errors on the component would be useful in controlling the manufacturing process and in understanding the functional aspects.

MEASUREMENT AND EVALUATION OF RELATIONSHIP BETWEEN GEOMETRICAL FEATURES OF ENGINEERING COMPONENTS.

Measurements are carried out on engineering components and analysed to check the conformity of the components to specification. This paper discusses different methods that are useful for assessing the errors on the dimensions, form and position of geometric features. A new approach called the median technique, which gives minimum values of errors is introduced. © 1986 Taylor and Francis Group, LLC.