JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Pre-requisites

Machine Tools, Metrology

Course Objectives:

• To give the basic precision engineering methodology and state-of-the-art concepts for designing high-precision CNC machines and products.
• The course is specifically tailored to teach the novel design principles leading to improved machine performance and reliability.
• To apply the acquired knowledge to other design efforts and fields as well

Course Outcomes

At the end of the course, the student will be able to:

• Apply fits and tolerances for parts and assemblies according to ISO standards.
• Apply selective assembly concept for quality and economic production.
• Assign tolerances using principles of dimensional chains for individual features of a part or assembly.
• Evaluate the part and machine tool accuracies.
• Analyze the causes for dimensional and geometrical errors prior to and during machining and suggest remedies

UNIT - I

Concepts of Accuracy: Introduction – Concept of Accuracy of Machine Tools – Spindle and Displacement Accuracies – Accuracy of numerical Control Systems – Errors due to Numerical Interpolation Displacement Measurement System and Velocity Lags. Geometric Dimensioning and Tolerance: Tolerance Zone Conversions – Surfaces, Features, Features of Size, Datum Features – Datum Oddly Configured and Curved Surfaces as Datum Features, Equalizing Datum –Datum Feature of Representation – Form Controls, Orientation Controls – Logical Approach to Tolerance.

UNIT - II

Datum Systems: Design of freedom, Grouped Datum Systems – different types, two and three mutually perpendicular grouped datum planes; Grouped datum system with spigot and recess, pin and hole; Grouped Datum system with spigot and recess pair and tongue – slot pair – Computation of Transnational and rotational accuracy, Geometric analysis and application.

UNIT - III

Tolerance Analysis: Process Capability, Mean, Variance, Skewness, Kurtosis, Process Capability Metrics, Cp, Cpk, Cost aspects, Feature Tolerances, Geometric Tolerances. Tolerance Charting Techniques: Operation Sequence for typical shaft type of components, Preparation of Process drawings for different operations, Tolerance worksheets and central analysis, Examples. Design features to facilitate machining; Datum Features – functional and manufacturing. Components design – Machining considerations, Redesign for manufactured parts examples

UNIT - IV

Surface finish, Review of relationship between attainable tolerance grades and different machining process. Cumulative effect of tolerances sure fit law, normal law and truncated normal law.

R19 M.Tech. Advanced Manufacturing Systems

UNIT - V

Measuring Systems Processing: In process or in-situ measurement of position of processing point- Post process and on-machine measurement of dimensional features and surface-mechanical and optical measuring systems.

TEXT BOOKS:

• 1. Precision Engineering in Manufacturing by Murthy R. L., New Age International (P) limited, 1996.
• 2. Geometric Dimensioning and Tolerancing by James D. Meadows, Marcel Dekker Inc. 1995.

REFERENCE BOOK:

• 1. Engineering Design – A systematic Approach by Matousek, Blackie & Son Ltd, London. R19 M.Tech. Advanced Manufacturing Systems M. TECH. I Year I Sem. (AMS)