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CNC MACHINE TOOLS (18ME821)

CNC MACHINE TOOLS

Course Code 18ME821 
CIE Marks 40
Teaching Hours /Week (L:T:P) 3:0:0 
SEE Marks 60
Credits 03 
Exam Hours 03


Course Learning Objectives:

  • To understand fundamentals of the CNC technology.
  • To get exposed to constructional features of CNC machine tools.
  • To know the concepts of CNC machine tool drives and feedback systems.
  • To understand the programming methods in CNC machines.
  • To understand the cutting tools used, and work holding devices on CNC machine tools.


Module-1

INTRODUCTION TO CNC MACHINE TOOLS: Evolution of CNC Technology, principles, features, advantages, applications, CNC and DNC concept, classification of CNC Machines – turning centre, machining centre, grinding machine, EDM, types of control systems, CNC controllers, characteristics, interpolators– Computer Aided Inspection.

Module-2

STRUCTURE OF CNC MACHINE TOOL: CNC Machine building, structural details, configuration and design, guide ways – Friction, Anti friction and other types of guide ways, elements used to convert the rotary motion to a linear motion – Screw and nut, recirculating ball screw, planetary roller screw, recirculating roller screw, rack and pinion, spindle assembly, torque transmission elements – gears, timing belts, flexible couplings, Bearings.

Module-3

DRIVES AND CONTROLS: Spindle drives – DC shunt motor, 3 phase AC induction motor, feed drives –stepper motor, servo principle, DC and AC servomotors, Open loop and closed loop control, Axis measuring system – synchro, synchro-resolver, gratings, moirĂ© fringe gratings, encoders, inductosysn, laser interferometer.


Module-4

CNC PROGRAMMING: Coordinate system, structure of a part program, G & M Codes, tool length compensation, cutter radius and tool nose radius compensation, do loops, subroutines, canned cycles, mirror image, parametric programming, machining cycles, manual part programming for machining centre and turning centre. Computer Aided CNC Part Programming: Need for computer aided part programming, Tools for computer aided part programming, APT, CAD/CAM based part programming for well-known controllers such as Fanuc, Heidenhain, Sinumerik etc., and generation of CNC codes from CAM packages.

Module-5

TOOLING AND WORK HOLDING DEVICES: Introduction to cutting tool materials – Carbides, Ceramics, CBN, PCD–inserts classification, qualified, semi qualified and pre-set tooling, tooling system for Machining centre and Turning centre, work holding devices for rotating and fixed work parts, modular fixtures, economics of CNC, maintenance of CNC machines.

Course Outcomes: At the end of the course the student will be able to:

CO1: Understand evolution, classification and principles of CNC machine tools.
CO2: Learn constructional details of CNC machine tools, selection of standard components used for CNC machine tools for accuracy and productivity enhancement.
CO3: Select drives and positional transducers for CNC machine tools.
CO4: Apply CNC programing concepts of for two axis turning centers and three axis vertical milling
centers to generate programs different components.
CO5: Generate CNC programs for popular CNC controllers.
CO6: Analyse and select tooling and work holding devices for different components to be machined on
CNC machine tools.

Question paper pattern:

  • The question paper will have ten full questions carrying equal marks.
  • Each full question will be for 20 marks.
  • There will be two full questions (with a maximum of four sub- questions) from each module.
  • Each full question will have sub- question covering all the topics under a module.
  • The students will have to answer five full questions, selecting one full question from each module.

Textbook

1 Mechatronics HMT Tata McGraw-Hill Publishing Company Limited, New Delhi 2005
2 Computer Control of Manufacturing systems Koren Y McGraw Hill 1986
3 Computer Numerical Control Machines Radhakrishnan P New Central Book Agency 2002

Reference Books

1 CNC Machining Hand Book James Madison Industrial Press Inc 1996
2 Programming of CNC
Machines Ken Evans, John Polywka& Stanley Gabrel Industrial Press Inc, New York Second Edition2002
3 CNC Programming Hand book Peter Smid Industrial Press Inc 2000
4 CAD/CAM Rao P.N. Tata McGraw-Hill Publishing Company Limited 2002
5 Computer Numerical Control Warren S. Seames Thomson Delmar Fourth Edition 2002

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