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  2. CENTRAL INSTITUTE OF HAND TOOL • CIHT is an autonomous organization. • CIHT is a National Institute. • CIHT was established in 1983 with assistance from UNDP, Government of India and Government of Punjab. • CIHT is aspiring for latest technology to be a leader in region.
  3. SERVICE OFFERED AT CIHT • Consultancy. • Tool Room Services. • Heat Treatment Shop. • Forge Shop. •Testing and quality control. •Training services.
  4. ADDRESS OF THE COMPANY:-Central Institute of Hand Tools Maqsudan, Opp. ShaheedBhagat Singh Colony, G.T. Road, Bye Pass, Jalandhar City - 144 008, State - Punjab, India. Phone: +91.181.2290196 E-mail:
  5. COMPUTER NUMERICAL CONTROL (CNC) MACHINES CNC is a microprocessor based control system that accepts a set of program instructions, processes and sends output control information to a machine tool, accepts feedback information acquired from a transducer placed on the machine tool and based on the instructions and feedback, assures that proper motion, speed and operation occur. A CNC system basically consists of the following: (a) Central processing unit (CPU) (b) Servo control unit (c) Operator control panel (d) Machine control panel (e) Programmable logic controller (f) Other peripheral devices
  7. Basic CNC Principles Coordinates System
  8. TYPES OF CNC MACHINE •Lathes for metal and plastics  Used to produce 3D product shapes and moulds for plastic products. •Milling machine for mould making and surface milling. Used to produce dies for die cutting printed products •Drilling machine used in making drill in surface. •Boring machine to increase the diameter of the hole. •Grinding machine to obtain better surface texture.
  9. CNC LATHE •Automated version of a manual lathe. Programmed to change tools automatically. •Used for turning and boring wood, metal and plastics.
  10. HOW CNC WORKS •Controlled by G and M codes. •These are number values and co-ordinates. •Each number or code is assigned to a particular operation. •Typed in manually to CAD by machine operators. •G&M codes are automatically generated by the computer software
  11. FEATURES OF CNCMACHINERY •The tool or material moves. •Tools can operate in 1-5 axes. •Larger machines have a machine control unit (MCU) which manages operations. •Movement is controlled by a motors (actuators). Feedback is provided by sensors (transducers) •Tool magazines are used to change tools automatically.
  12. •Most are made from high speed steel (HSS), tungsten carbide or ceramics. •Tools are designed to direct waste away from the material. •Some tools need coolant such as oil to protect the tool and work. TOOL
  13. CNC PROGRAMMING BASICS •CNC instructions are called part program commands. •When running, a part program is interpreted one command line at a time until all lines are completed. •Commands, which are also referred to as blocks, are made up of words which each begin with a letter address and end with a numerical value.
  14. •Each letter address relates to a specific machine function. “G” and “M” letter addresses are two of the most common. A “G” letter specifies certain machine preparations such as inch or metric modes, or absolutes versus incremental modes. •A “M” letter specifies miscellaneous machine functions and work like on/off switches for coolant flow, tool changing, or spindle rotation. Other letter addresses are used to direct a wide variety of other machine commands.
  17. IMPORTANT THINGS TO KNOW • Coordinate System • Units, incremental or absolute positioning • Coordinates: X,Y,Z, RX,RY,RZ • Feed rate and spindle speed • Coolant Control: On/Off, Flood, Mist • Tool Control: Tool and tool parameters
  18. CNC PROGRAMMING •Programming consists of a series of instructions in form of letter codes. •Preparatory Codes: G codes- Initial machining setup and establishing operating conditions •N codes- specify program line number to executed by the MCU •Axis Codes: X,Y,Z - Used to specify motion of the slide along X, Y, Z direction •Feed and Speed Codes: F and S- Specify feed and spindle speed •Tool codes: T – specify tool number •Miscellaneous codes – M codes For coolant control and other activities
  19. O - Program number (Used for program identification) N - Sequence number (Used for line identification) G - Preparatory function X - X axis designation Y - Y axis designation Z - Z axis designation R - Radius designation F – Feed rate designation S - Spindle speed designation H - Tool length offset designation D - Tool radius offset designation T - Tool Designation M - Miscellaneous function
  20. EXPLANATION OF COMMONLY USED G CODES • G00 – Preparatory code to control final position of the tool and not concerned with the path that is followed in arriving at the final destination. • G01 – Tool is required to move in a straight line connecting current position and final position. Used for tool movement without any machining- point to point control. (linear interpolation) • G02 – Tool path followed is along an arc specified by I, J and K codes.( circular interpolation)
  21. IMPORTANT G CODES G00 Rapid Transverse G01 Linear Interpolation G02 Circular Interpolation, CW G03 Circular Interpolation, CCW G17 XY Plane,G18 XZ Plane,G19 YZ Plane G20/G70 Inch units G21/G71 Metric Units G40 Cutter compensation cancel G41 Cutter compensation left G42 Cutter compensation right G43 Tool length compensation (plus) G43 Tool length compensation (plus) G44 Tool length compensation (minus) G49 Tool length compensation cancel G80 Cancel canned cycles G81 Drilling cycle G82 Counter boring cycle G83 Deep hole drilling cycle G90 Absolute positioning G91 Incremental positioning
  22. IMPORTANT MCODES M00 Program stop M01 Optional program stop M02 Program end M03 Spindle on clockwise M04 Spindle on counterclockwise M05 Spindle stop M06 Tool change M08 Coolant on M09 Coolant off M10 Clamps on M11 Clamps off M30 Program stop, reset to start
  23. RULES FOE PROGRAMMING • Restrictions on CNC blocks • Each may contain only one tool move • Each may contain any number of non-tool move G- codes • Each may contain only one feed rate • Each may contain only one specified tool or spindle speed
  24. • The block numbers should be sequential. • Both the program start flag and the program number must be independent of all other commands (on separate lines) • The data within a block should follow the sequence.
  25. 45 36 FACING G95G90G71G54 G96S500M03LMS=700F0.2 G00X92.0Z0.0 Z-1.0 G01X-1.5 X92.0Z-1.0 G00Z-2.0 G01X-1.5 G00X92.0Z-2.0 G00Z-3.0 G01X-1.5 G00X92.0Z-3.0 G00Z-4.0 G01X-1.5 G0X0Z0D0 M05 M09 M30 90
  26. TURNING 100 75 80 G95G90G71G54 G96S500M03LIMS=700F0.2 X79.0 G01Z-100.0 G00X79.0Z0.0 X78.0 G01Z-100.0 G00X77.0Z0.0 X76.0 G01Z-100.0 G00X77.0Z0.0 X75.0 G00X75.Z0.0 G00X80.0Z10.0 G0X0Z0D0 M05 M09 M30
  27. 5 10 5 STEP TURNING ɸ75 ɸ80 ɸ70ɸ82 G95G90G71G54 G96S500M03LIMS=700F0.2 T1D1M06 G0X84.0Z0.0 X81.0 G01Z-30.0 G0X81.0Z0.0 X80.0 G01Z-30.0 G0X79.0Z0.0 G01Z-15.0 G0X79.0Z0.0 X78.0 G01Z-15.0 G0X78.0Z0.0 X76.0 G01X76.0Z0.0 X75.0 G01Z-15.0 G0X75.0Z0.0 X73.0 G01Z-5.0 G0X73.0Z0.0 X70.0 G01Z-15.0 G0X72.0Z10.0 GOXOZODO M05 M09 M30
  28. TAPER TURNING ɸ75 ɸ70 G95G90G71G54 G96S500M03LIMS=700F0.2 T1D1M06 G00X76.0Z0.0 X74.0 G01X75.0Z-30.0 30 G00X76.0Z0.0 X72.0 G01X75.0Z-30.0 G00X76.0Z0.0 X71.0 G01X75.0Z-30.0 G00X76.0Z0.0 X70.0 G01X75.0Z-30.0 G00X76.0Z10.0 GOXOZODO M05 M09 M30
  29. GROOVING 60 5 30 30 ɸ60 G95G90G71G54 G96S500M03LIMS=700F0.2 T1D1M06 G00X62.0Z0.0 Z-30.0 G01X59.0 G00X62.0 G01X58.0 G00X62.0 G0157.0 G00X62.0 G01X56.0 G00X62.0 G0155.0 G00X62.0 Z10.0 G0X0Z0D0 M05 M09 M30
  30. ADVANTAGES (a) High Repeatability and Precision, e.g. Aircraft parts. (b) Volume of production is very high. (c) Complex contours/surfaces need to be machined, e.g. Turbines. (d) Flexibility in job change, automatic tool settings, less scrap. (e) Safer, higher productivity, better quality. (f) Less paper work, faster prototype production, reduction in lead times. (g) Easier to program. (h) Easy storage of existing programs. (i) Avoids human errors. (j) Usually generates closer tolerances than manual machines. (k) Program editing at the machine tool. (l) Control systems upgrades possible. (m) Option -resident CAM system at machine tool. (n) Tool path verification
  31. DISADVANTAGES (a) Costly setup, skilled operators. (b) Computers, programming knowledge required. (c) Maintenance is difficult. (d) Machines have to be installed in air conditioned places