Previous year question paper for CNCMA (Diploma Mechanical Engineering 6th)

DETAILED CONTENTS

1. Introduction (07 hrs)

Basic concepts of NC, CNC & DNC, advantages &disadvantage of CNC

Machines, Application of CNC Machines, difference between conventional &

CNC Machines, Profitable applications of CNC Machines. Introduction to CAM.

2. Construction of CNC Machines (14 hrs)

Machine control unit, NC control, PLC control, its advantages &

disadvantages, Application and limitations of PLC machines, Axis designate

of CNC machines, special constructional requirement of CNC machines,

slide ways, bolt screw & nut assembly, Lubrication & cooling of CNC

machines, Spindle & spindle motors, axis drives motor, Swarf removal &

safety provision of CNC machines, Feedback mechanism in CNC

machines.

3. Tooling of CNC Machines (07 hrs)

Introduction, various cutting tools for CNC machines, Work holdingdevices,

automatic tool changer.

4. Control System (09 hrs)

Open & close loop control system, fundamental problem in control:

Accuracy, resolution, repeatability, instability, response & damping, type

ofposition control:

• Point to point

• Straight line

• Continuous

5. Part Programming (09 hrs)

Part programming and basic concepts of part programming, NC words, part

programming formats, simple programming for rational components, part

programming using conned cycles, subroutines and do loops, tool off secutter

radius compensation and wear compensation 

6. Common Problems in CNC Machines (05 hrs)

Common problems in mechanical, electrical, pneumatic, electronic and PC

components of NC machines, diagnostic study of common problems and

remedies, use of on-time fault finding diagnosis tools in CNC machines

7. Industrial Automation (05 hrs)

Meaning of automation, need of automation, different types of automation,

advantages/disadvantages of automation, Components of automated

system, concept of FMS.