Informatics Publishing Limited

M. Chellamalai ¹, Ali Maruf Hassan ¹, G. Ugrasen ¹, P. V. Shashi Kumar ¹

Affiliations
1 Central Manufacturing Technology Institute, Bangalore, IN

Abstract

Conventional dressing methods available commercially are single point and roller dressers. Dressing is essentially a sharpening operation designated to generate a specific topography on the working surface of the grinding wheel. These techniques have seldom been satisfactory for super abrasive wheels. There are problems of high dresser wear, insufficient grain protrusion, improper generation of profiles, stresses being induced into wheels, time consuming, shortcomings of loading induced deformation&shape distortion and very low dressing efficiencies. Numerous works have been published on the feasibility of laser dressing of grinding wheels till now. Based on the reports and research works, the present effort has been to actualize the same conditions of laser dressing in actual high speed grinding conditions. The work presents a favourable and opportune environment for the technology of laser dressing to shape into reality.

Keywords

Superabrasive, Grinding Wheel Dressing and Pulsed Fiber Laser.

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S. Usha ¹, P. V. Shashi Kumar ¹

Affiliations
1 Central Manufacturing Technology Institute, Bangalore, IN

Abstract

Conventional coordinate measuring machine posses problem for handling delicate components. Optical profile projectors require enormous time for manual cursor positioning to make measurements. A separate setup is called for inspecting the surface finish (microscope). These issues are addressed by a single setup using vision techniques for both precision measurements as well as to identify surface defects. This paper discusses about machine vision technique for metrology requirement and explain how ‘Vision for Metrology’ differs in terms of sensor requirement, lighting techniques, calibration methods and algorithm from a conventional vision system used for feature identification, recognition etc.

Keywords

Vision Metrology, Non-Contact Measurement.

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K. Niranjan Reddy ¹, Nithin Narayanan ², P. V. Shashi Kumar ¹, Sudhakar C. Jambagi ²

Affiliations
1 Micro Engineering & Nano Technology Department, Central Manufacturing Technology Institute, Tumkur Road, Bangalore, IN
2 National Institute of Technology Karnataka, Surathkal, IN

Abstract

Coordinate Measuring Machine (CMM) is a measuring system with a movable probing system and capability to determine spatial coordinates on a work piece surface, that can be further analyzed to arrive at the required parameters. As geometry of feature is not ideal, the number of points, their distribution and their computation method have an effect on the results of dimension, form and position and therefore on also coordinate system. Discrete point probing uses only few points to calculate the ideal circle; the outcome of this is incorrect information on form shape. For features having functional requirement like assembly, running accuracy form is critical and true shape of the feature is required. Hence, CMMs are developed with scanning feature; which supplies the large data quantities for evaluation. The optimization of scanning parameters like number of points for a feature is one of the important parameters in the coordinate metrology. The aim of the paper is to describe the effect of number of points for scanning a feature and optimization of this scanning parameter and to adopt the optimized scanning data to the discrete point probing system.

Keywords

CMM, Scanning, Discrete Point Probing, Form, Feature, Optimization.

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N. Balashanmugam ¹, K. Ankit ¹, K. Niranjan Reddy ¹, V. Shanmugaraj ¹, P. V. Shashi Kumar ¹

Affiliations
1 Central Manufacturing Technology Institute, Bangalore, IN

Abstract

Productivity in manufacture of high aspect ratio cylinders depends on how quickly the inspection parameters are measured and corrective actions are token. Long cylinders undergo a series of processes including bend removal and machining. These processes undergo a series of iterations consuming considerable amount of time for the measurement of straightness of cylinder. In this paper, a concept is proposed, where, the straightness of the bore of a cylinder (barrel) is measured in-situ on the machine. In this method, the barrel diameter and thickness are measured at number of planes using touch trigger probe and ultrasonic transducer respectively. Ultrasonic transducer assembly and the touch trigger probe are mounted on the turret of the CNC Turn Mill Centre. The setup for ultrasonic based measurement includes a nozzle for the supply of stream of liquid on the work piece, an ultrasonic transducer and a data capturing unit. Echo from ultrasonic waves is obtained back from the stream enabling the measurement of the relative position from the outer profile of the work piece to its internal profile. By orienting (rotating) the work piece at different locations in the same plane, thickness and diameters are measured. Straightness is measured by continuing to measure along the length of the cylinder. The thickness and diameters obtained are then used for the evaluation of straightness of the bore.

Keywords

Straightness, Cylinder, Touch Trigger Probe, Ultrasonic Transducer.

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S. Gopi Krishna ¹, Prakash Vinod ¹, P. V. Shashi Kumar ¹

Affiliations
1 Micro-Engineering and Nanotechnology Department, Central Manufacturing Technology Institute, Bangalore, IN

Abstract

The paper addresses the key design considerations for aerostatic bearings for ultra precision machines requiring nanometer precise spindle rotation and moderate axial and radial stiffness. The development in optical & opto-electronic industry, defence, space and nuclear research demands for high form less than 0.1 μm and surface finish in the order of 2-5 nm components to be used as optics. Aerostatic bearing spindles with nanometric accuracy are required to manufacture such high precision optics. Many research and developmental work has been carried out for the past three decades in the field of aerostatic bearing design and performance testing. The selection of suitable bearing type and configuration plays a critical role in achieving the spindle running accuracy in nanometre range. This paper focuses on the selection criteria of bearing film thickness, air bearing types and configurations, air inlet feeding media, and the material selection. The errors associated with the aerostatic bearings and its effect on the surface finish and form accuracy of the component is also discussed in the paper. This gives a clear and basic insight to designers to begin with the aerostatic bearing spindle design for ultra precision machines.

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V. A. P. Sarma ¹, H. K. Mallappa ¹, P. V. Shashi Kumar ¹

Affiliations
1 Metrology Laboratory, Micro Engg. & Nano Technology Dept., Central Manufacturing Technology Institute, Tumkur Road, Bangalore-560022, IN

Abstract

Some of the artifacts used extensively as calibration masters for precision measuring instruments are made up of accurate spherical surfaces. In some of such artifacts, only a small portion of sphere is exposed (coverage area) where the diametrical methods can't be used for calibration. In addition, some of the optical elements with spherical surfaces having large radius of curvature present only small area for measurement. The methodology adopted in measuring such spherical surfaces and effect of coverage area on the accuracy of measurements along with associated uncertainty of measurement (UOM) are investigated and discussed in this paper.

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K. Niranjan Reddy ¹, P. V. Shashi Kumar ¹, Somashekar Rao ¹

Affiliations
1 Micro Engineering and Nano Technology Dept., Central Manufacturing Technology Institute, Tumkur Road, Bangalore, IN

Abstract

Today, wire EDM is providing the most economical solution for manufacture of Dies, Punches and special tools required in almost all the engineering industries. Often, Wire EDM is found to be the only solution for parts, which are extremely difficult or Impossible to handle with any other method of machining. Now, the same process is found to be Ideally suited for manufacture of micro components. These products require very high surface finish, profile accuracy and smallest possible radius In the corners. With the continuous refinement and innovations in the technology, the design of the machine, the spark generator and the operation software the Micro finish and Micro Wire EDMs have been developed. This paper gives the main features of the Micro Finish & Micro wire EDM and the some of the parts machined on this type of machine, which give insight to the use of this type of machine In precision manufacturing.

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P. V. Shashi Kumar ¹, A. H. Naveen Kumar ¹, C. Gajendran ¹

Affiliations
1 Central Manufacturing Technology Institute, Tumkur Road, Bangalore 560022, IN

Abstract

Nano surfaces are the surfaces having geometrical parameters in nano scale. The enhanced geometrical, physical and chemical properties of nano surfaces play an important role in redefining the functionality of the products. The concept of redefining the function represents a shift of emphasis from manufacturing towards function or performance. To some extent the manufacturing requirements of the surface has masked the more relevant functional parameters. Ideally, in order to be of use, the definition and operation should mimic the function. Parameters such as Ra are simply descriptions of the waveform. Further, surface finish is critical in vertical flow of, say, electricity or heat because it determines the number and shape of contacts. This paper discusses the properties and the processing techniques to produce nano surfaces. The process variables of these processing techniques can be controlled and manipulated to suit the functionality of the product under production. The processing techniques include conventional machining, advanced non-conventional machining and advanced nano-surface engineering techniques. Finally the applications of nano surfaces in different fields are also discussed.

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K. Niranjan Reddy ¹, P. V. Shashi Kumar ¹

Affiliations
1 Micro Engineering & Nano Technology Department, CMTI, Bangalore, IN

Abstract

In Non Destructive Testing (NDT) ultrasonic flaw detectors are extensively used for inspection of metallic raw materials like forgings, castings and rolled sections for internal imperfections and defects like cracks, voids, inclusions etc. In these Ultrasonic flaw detectors Ultrasonic standard reference blocks are used as masters for allowable level of flaws in metallic raw materials. These reference blocks are also used for calibration of flaw detectors. These reference blocks are made with precisely drilled flat bottom holes (FBH) of different diameters depending on the allowable level of flaws. Reference blocks with flat bottom holes of dia from 2 mm down to dia 0.5 mm are mainly used in aerospace applications. These blocks are to be made in the same material that is to be inspected. The typical test materials are Aluminium, Steel, Titanium and Nickel base alloys. This paper deals with micro-drilling of 0.5 mm diameter flat bottom holes in Titanium material Ultrasonic Standard Reference Blocks.

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P. V. Shashi Kumar ¹, C. Gajendran ¹

Affiliations
1 Central Manufacturing Technology Institute, Tumkur Road, Bangalore-560 022, IN

Abstract

Micro engineering is divided into two major areas. These are, Micro devices and Micro sensors, Micro devices include, electro statically driven motors. Micro-robots, Micro-pumps, Micro gears, etc. Micro sensors include. Mechanical sensors. Accelerometers, Pressure sensors, Transducers, etc. In any case, the overall dimension of any micro-system are in the order of few millimeters. This article gives a overview of this new technology-'Micro Engineering", covering the latest trends In micro-fabrication, microsensor technology and micro devices.

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V. A. P. Sarma ¹, P. V. Shashi Kumar ¹

Affiliations
1 Central Manufacturing Technology Institute, Tumkur Road, Bangalore-560 022, IN

Abstract

Describes various micromachining phenomena, the types of micromachining processes amenable to these phenomena. The micromachining processes considered are micro milling, micro grinding, EDM, LBM, EBM, LBM chemical etching, ECM, recomposition, vapour deposition, etc. Describes the characteristics of each of these processes and the advantages/ limitations of them.

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