Recent Advancement of CNC Technology
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The document discusses the history and development of computer numerical control (CNC) machines. It describes how CNC machines evolved from early numerical control machines run by punched cards to modern CNC machines with onboard computers. The document also covers CNC part programs, basic CNC machine components, motion control types, advantages like precision and disadvantages like higher costs compared to manual machines.
Recent Advancement of CNC Technology
- 1. LOGO 1
- 2. Dept. of mechanical Engineering, GIET,BBSR Highlights 1 HISTORY OF CNC 2 ABOUT CNC 3 CNC PART PROGRAM 4 ADVANTAGE & DISADVANTAGE 5 APPLICATION AND IMPROVEMENT 2
- 3. Dept. of mechanical Engineering, GIET,BBSR HISTORY OF CNC The concept is credited to John Parson (1947). Using punched cards he was able to control the position of a machine in an attempt to machine helicopter blade. US Air Force teamed up with MIT to develop a programmable milling machine (1949). In 1952, a three-axis Hydrotel milling machine was demonstrated. The term Numerical Control (NC) originated. The machine had an electromechanical controller and used punched cards. A new class of machines called machining centers and turning centers that could perform multiple machining processes was developed. Modern NC machine has a computer on board, Computer Numerical Control (CNC). They can run unattended at over 20,000 rpm (spindlier speed) with a feed rate of over 600 rpm and an accuracy of .0001 3
- 4. HISTORY OF CNC Dept. of mechanical Engineering, GIET,BBSR More recently, microprocessors have made CNC controls even cheaper. The Enhanced Machine Controller project, or EMC2, was a project to implement an Open Source CNC controller that was started by NIST, the National Institute of Standards and Technology as a demonstration. Some time in 2000, the project was taken into the public domain and Open Source, and EMC2 appeared a short time later in 2003. (1959 CNC Machine: Milwaukee-Matic-II was first machine with a tool changer) 4
- 5. ABOUT CNC Dept. of mechanical Engineering, GIET,BBSR Computer Numerical Control CNC Stands for Numerical control is a method of automatically operating a manufacturing machine based on a code of letters, numbers, and special characters. The numerical data required to produce a part is provided to a machine in the form of a program, called part program or CNC program. 5
- 6. ABOUT CNC The program is translated into the appropriate electrical signals for input to motors that run the machine. A CNC machine is an NC machine with the added feature of an on-board computer. Dept. of mechanical Engineering, GIET,BBSR 6
- 7. ABOUT CNC Dept. of mechanical Engineering, GIET,BBSR HAAS CNC Machines 7
- 8. ABOUT CNC Dept. of mechanical Engineering, GIET,BBSR Basic Components An NC system consists of the machine tools, the part-program, and the machine control unit (MCU). 8
- 9. ABOUT CNC Dept. of mechanical Engineering, GIET,BBSR Machine Tools The machine tools perform the useful work. A machine tool consists of. A worktable, One or more spindles, motors and controls, Cutting tools, Work fixtures, and. Other auxiliary equipment needed in the machining operation. The drive units are either powered by stepping motors (for open-loop control), servomotors (for close-loop control), pneumatic drives, or hydraulic drives. 9
- 10. CNC PART PROGRAM The part-program is a collection of all data required to produce the part. It is arranged in the form of blocks of information. Each block contains the numerical data required for processing a segment of the work piece. Dept. of mechanical Engineering, GIET,BBSR PART PROGRAM MANUAL PROGRAM COMPUTER ASSITED PART PROGRAM Part program is of two type: 10
- 11. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR PROCESS PLANNING JOB & TOOL SET UP PLANNING AXES SELECTION MACHINING PATH PLANNING TOOL SELECTION PART PROGRAM WRITTING CUTTING PROCES PARAMETER PLANNING PART PROGRAM PROVING 11
- 12. CNC PART PROGRAM MANUAL PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Manual part program is written in a special set of instruction called manuscript. The instruction are prepared in précised manner because the typist prepare the NC tape directly from the manuscript Manuscript includes instructions and also other data such as other preparatory commands, miscellaneous instructions and speed/feed specifications all of which need to operate the machine under tape control . MANUAL PART PROGRAM PTP JOBS COUNTOURING JOBS 12
- 13. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR COMPUTER ASSISTED PART PROGRAMMING Programmers Activities: Geometry workspace entry Entry of sequence of operation Computer Activities: Input Translation Advance computation Cutting tool offset calculation Post processing 13
- 14. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Preparatory command (G code) The G codes prepare the MCU for a given operation, typically involving a cutter motion. G00 rapid motion, point-to-point positioning G01 linear interpolation (generating a sloped or straight cut) G06 parabolic interpolation (produces a segment of a parabola) G17 XY plane selection G20 circular interpolation G28 automatic return to reference point G33 thread cutting 14
- 15. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Miscellaneous commands (M code) M00 program stop M03 start spindle rotation (cw) M06 tool change M07 turn coolant on Feed commands (F code) Used to specify the cutter feed rates in inch per minute. Speed commands (S code) Used to specify the spindle speed in rpm. Tool commands (T code) Specifies which tool to be used, machines with automatic tool changer. 15
- 16. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR CNC Machine Axes of Motion The coordinate system used for the tool path must be identical to the coordinate system used by the CNC machine. The standards for machine axes are established according to the industry standard report EIA RS-267A. 16
- 17. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR CNC Machine Axes of Motion 17
- 18. CNC PART PROGRAM CNC MOTION CONTROL POINT TO POINT MOTION STRAIGHT CUT MOTION COUNTORING MOTION Dept. of mechanical Engineering, GIET,BBSR 1. Point-to-point (PTP) MOTION The cutting tool is moved relative to the work piece (i.e. Either the cutting tool moves, or the work piece moves) until the cutting tool is at a numerically defined position and then the motion is paused. The cutting tool then performs an operation. When the operation is completed, the cutting tool moves relative to the work piece until the next point is reached, and the cycle is repeated. The simplest example of a PTP NC machine tool is the NC drilling machine. 18
- 19. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Straight-cut MOTION Straight-cut system are capable of moving the cutting tool parallel to one of the major axes (X-Y-Z) at a controlled rate suitable for machining. It is appropriate for performing milling operations to fabricate work pieces of rectangular configurations. Straight-cut NC systems can also perform PTP operations. 19
- 20. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Contouring NC In contouring (continuous path) operations, the tool is cutting while the axes of motion are moving. The axes can be moved simultaneously, at different velocity. The path of the cutter is continuously controlled to generate the desired geometry of the work piece. 20
- 21. CNC PART PROGRAM Dept. of mechanical Engineering, GIET,BBSR Example of a part program N1 G00 X-35 Z-5 N2 G01 X10 Z0 F100 N3 G01 X0 Z-30 F100 N4 G01 X10 Z0 F100 N5 G01 X0 Z-30 F100 N6 G01 X10 Z-0 F100 N7 G01 X0 Z-40 F100 N8 G00 X-35 Z-5 M30 (This is a manual part program for lathe machining) 21 P1 P2 P3 P4 +X +Z -X -Z
- 22. Dept. of mechanical Engineering, GIET,BBSR ADVANTAGE & DISADVANTAGE ADVANTAGE CNC machines can be used continuously 24 hours a day, 365 days a year and only need to be switched off for occasional maintenance. CNC machines are programmed with a design which can then be manufactured hundreds or even thousands of times. Each manufactured product will be exactly the same. Less skilled/trained people can operate CNCs unlike manual lathes / milling machines etc.. which need skilled engineers. CNC machines can be updated by improving the software used to drive the machines Training in the use of CNCs is available through the use of ‘virtual software’. This is software that allows the operator to practice using the CNC machine on the screen of a computer. The software is similar to a computer game. 22
- 23. Dept. of mechanical Engineering, GIET,BBSR ADVANTAGE & DISADVANTAGE CNC machines can be programmed by advanced design software such as Pro/DESKTOP®, enabling the manufacture of products that cannot be made by manual machines, even those used by skilled designers / engineers. Modern design software allows the designer to simulate the manufacture of his/her idea. There is no need to make a prototype or a model. This saves time and money. One person can supervise many CNC machines as once they are programmed they can usually be left to work by themselves. Sometimes only the cutting tools need replacing occasionally. A skilled engineer can make the same component many times. However, if each component is carefully studied, each one will vary slightly. A CNC machine will manufacture each component as an exact match. 23
- 24. Dept. of mechanical Engineering, GIET,BBSR ADVANTAGE & DISADVANTAGE DISADVANTAGES CNC machines are more expensive than manually operated machines, although costs are slowly coming down. The CNC machine operator only needs basic training and skills, enough to supervise several machines. In years gone by, engineers needed years of training to operate centre lathes, milling machines and other manually operated machines. This means many of the old skills are been lost. Less workers are required to operate CNC machines compared to manually operated machines. Investment in CNC machines can lead to unemployment. Many countries no longer teach pupils / students how to use manually operated lathes / milling machines etc... Pupils / students no longer develop the detailed skills required by engineers of the past. These include mathematical and engineering skills 24
- 25. Dept. of mechanical Engineering, GIET,BBSR ADVANTAGE & DISADVANTAGE COMPUTER NUMERICAL CONTROL - MACHINE MANUALLY OPERATED CENTRE LATHE 25
- 26. APPLICATION AND ADVANCEMENT APPLICATION CNC machine is used In the metal removal industry In the metal fabrication industry In the electrical discharge machining industry In the woodworking industry Laser welding in automobile industry Laser machining and Cutting Dept. of mechanical Engineering, GIET,BBSR Small parts made using EDM Laser welding in automobile industry LASER MACHINING 26
- 27. Dept. of mechanical Engineering, GIET,BBSR APPLICATION AND ADVANCEMENT Other Industries where CNC machines are used: Many forms of lettering and engraving systems use CNC technology. Water jet machining uses a high pressure water jet stream to cut through plates of material. CNC is even used in the manufacturing of many electrical components. For example, there are CNC coil winders, and CNC terminal location and soldering machines. 27
- 28. APPLICATION AND ADVANCENENT ADVANCES OF CNC: CNC are operated using DNCs Reverse engineering is possible only because of CNC Robotics technology is introduced in CNC technology 3D printing is done using CNC. Advance machining process such as EDM,LBM, Stereolithography (SLA), Fused Deposition Modeling (FDM) Rapid prototyping, Rapid manufacturing concepts are developed after CNC . Dept. of mechanical Engineering, GIET,BBSR 28 A rapid prototyping machine using selective laser sintering
- 29. LOGO Dept. of mechanical Engineering, 29 GIET,BBSR
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