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The functional behaviour of manufactured surfaces is influenced by errors that are present on the surface. The errors on surface can be classified into roughness, waviness and form errors. Separation of the roughness component is done by 'filtering' that establishes a suitable 3D-reference surface consisting of waviness and form errors. In this article, details of Gaussian filtering technique are discussed and results of processing of a few typical manufactured surfaces using this filtering method are included. The practical and the reference surfaces established are further analyzed by random process techniques to bring out the waviness contents anaphase matching.

Feature Based System (FBS) capture information regarding manufacturing, function, and assembly at the design stage. This approach generates simple and easy to use database, which is necessary to integrate CAD/CAM. Most of the FBS use solid models, as they provide the most concise representation of part geometry. However special hardware and software are required for solid modeling. Also in majority of the industries, the design data currently exists in the form of 2D orthographic drawings as 3D modeling softwares are too expensive. This paper describes a fully automated experimental feature recognition system for process planning, which extracts the feature information from 2D orthographic drawing of sheet metal components for further use to generate process plan without any user interaction.

Geometric form of engineering surfaces is important in majority of applications. Form conformance is verified using appropriate measuring instruments/set-ups and the production process is monitored with the results of measurement. Confusion still exists in the minds of practitioners and researchers with regard to the form measurement and assessment method. In this paper, the important issues of form measurement and assessment of engineering surfaces are discussed taking appropriate examples.

Detailed analysis of revolute pairs with single axis, single notch and intermediate shape has been carried out with FEM package. Based on this analysis, the design of monolithic linear stages making use of single axis/single notch revolute pairs have been analyzed. Finally, the design of two axes monolithic stages with single axis and single notch revolute pair structures have been reported.

Computer aided process planning (CAPP) is an important interface between computer aided design (CAD) and computer aided manufacturing (CAM) in computer integrated manufacturing (CIM). Operation sequencing in process planning is concerned with the selection of machining operations in steps that can produce each form feature of the part by satisfying relevant technological constraints specified in the part drawing. A single sequence of operations may not be the best for all the situations in a changing production environment with multiple objectives such as minimizing number of set-ups, maximizing machine utilization and minimizing number of tool changes. This paper demonstrates the application of genetic algorithms as a global search technique for a quick identification of optimal or near optimal operation sequences in a dynamic planning environment. A novel initialization scheme for representing the genetic code and a new crossover operator are designed to retain the local operation precedence for each form feature. Since sequences can be obtained quickly, this approach can actually be used by the process planner to generate alternative feasible sequences for the prevailing operating environment. ? 1999 Taylor & Francis Ltd.

This paper discusses mutually orthogonal revolute pairs in tandem (MORPT) angular stage and mutually orthogonal and coincident revolute pair (MOCRP) angular stage for two axes deflection of � 1� (0.01745 rad). Theoretical analysis has been compared with the results of finite element method (FEM) analysis. Based on this analysis,single notch revolute pair has been selected for MORPT angular stage and single axis revolute pair has been selected for MOCRP angular stage for fabrication. The deflection of prototypes was measured with a Twyman and Green Interferometer set-up. The loading is done with piezo-actuator providing a resolution of 10 -6 rad for the range of 1� deflection.

In general, systematic and accidental non-conformities contribute to the non-deterministic nature of the manufacturing processes. The measurement data generated during production and inspection should be further processed to get the desired information contained in it. The measurement data can be considered as the sum of the desired information and certain random errors and variations. Processing requires a method that reduces the effect of wild non-conformities giving due importance to the desired information present in the original measurement data. In this paper an efficient L1-approximation is presented and used for form error evaluation of engineering surfaces to show its effectiveness when the measurement data contains wild points. The result is compared with the least-squares solution. The use of L1-approximation for form error evaluation will also help to identify the wild points present on the surface of the part that can be compensated by further operation(machining) to produce a better quality part. ? 1998 Elsevier Science S.A. All rights reserved.

In this part, the concept of enveloping tangent planes dealing with gear geometry and normal deviations is applied to bevel gears. Exact spherical involute is established by the procedure outlined in this paper. Straight tooth and spiral tooth bevel gears are considered in this paper. The method of determining the normal deviation from the idealized surface and the validation of the method are reported here. Effectiveness of the proposed method for obtaining normal deviation is established by considering spiral bevel gear geometry based on circular arc. ? 1998 Elsevier Science Ltd.

This part reports a preliminary work wherein spur and helical gears are established from first principle using the concept of tangent line and plane, respectively. The coordinates of the ideal surfaces are obtained which can be verified on a Coordinate Measuring Machine. From the measurements, the normal deviations from ideal surfaces can be obtained by the method proposed in this paper. This method is validated by introducing a known error at a specific point on the ideal surface. Significance of the normal deviation method proposed is brought out by considering crowned helical gear surface. ? 1998 Elsevier Science Ltd.

This paper analyses the effect of relief and rake angles on the effective generating profile of the helical gear shaping cutter. In a gear shaping process, the conjugate motion between the gear blank and the cutter, along with the cutting motion generates the gear. The cutter is a modified version of the rack/pinion incorporating rake and relief angles. Effect of different sharpening methods has also been discussed in this paper. Certain design modifications are proposed to minimize the deviation from the ideal profile in case of rack as well as pinion cutters.

Dissimilar metal welds between low-alloy ferritic steels and austenitic stainless steels are widely used in power station steam generators. This dissimilar metal joint has got problems and indeed several premature failures have occured well below the designed lifetime. To overcome the above problem a transition metal joint with Alloy 800 as transition piece is used between low-alloy steel and austenitic stainless steel. This paper gives the details of friction welding between Alloy 800 and 2.25 Cr-1 Mo steel. The joints were subjected to different mechanical strength tests, microstructural observation and thermal exposure studies simulating the service conditions.