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Intro to NC Machining

Intro to NC Machining. A Cuyler , Baehr Production!. What is this NC Machining All about?. What is it? How can it be set up? Let’s take a look. NC. DNC. CNC. NC-Numerical Control A Programmed path is loaded into a machine then executed by a series of codes the machine can understand.

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Intro to NC Machining

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  1. Intro to NC Machining A Cuyler , Baehr Production!

  2. What is this NC Machining All about? What is it? How can it be set up? Let’s take a look. NC DNC CNC

  3. NC-Numerical Control A Programmed path is loaded into a machine then executed by a series of codes the machine can understand.

  4. Computer Computer Computer Machine Tool Machine Tool Machine Tool CNC- Computer Numerically controlled A Dedicated Computer acts as the controller for each tool.

  5. Central Computer Machine Tool MachineTool Machine Tool Machine Tool DNC- Distributed Numerically controlled One central Computer controls all other Machine Tools on the factory floor.

  6. Which type of NC system do we use in class?

  7. Goals of NC Machining • Increase Production • Improve the Quality and Accuracy of parts • Stabilize Manufacturing Costs • Manufacture and assemble complex parts quickly

  8. Timeline of NC Machining • Single items produced by craftspeople • Eli Whitney (Cotton Gin) - Interchangeable Parts • Engineer designed parts for production (tolerances) • WW II - development of servo motors (electrically aimed guns) Military products created the need to produce precision quickly and accurately. • Servo motors applied to machine tools as a result.

  9. Timeline Continued • 1945- University of Pennsylvania- ENIAC to assist with Engineering calculations. • 1945- Parsons corporation awarded USAF contract • 1952- Parsons corporation subcontracted with MIT to develop first NC machine. • 1960’s- NC machines become affordable and common in industry to produce parts.

  10. Timeline Continued • 1970’s- Programs stored on Punch tapes and Cards. Programmable controllers replace relays. • 1980’s- Computer assisted Part Programming- computer is used for translating data and performing necessary calculations, creates punch tape. • 1990’s- CNC And DNC become widely used in industry. Punch cards become obsolete. • Currently 85 percent of machine tools produced are run by CNC. Punch Tape

  11. ENIAC

  12. First NC Machine at MIT Today

  13. Advantages Of CNC • Increased productivity after programming is completed • Reliability - reduces human error • Often eliminates need for special jigs and fixtures • Makes possible the machining of complex shapes requiring simultaneous 3 axis motion

  14. Advantages • Single part and production runs can be programmed and machined with minimum effort and cost. • Programs can readily be altered and re-run • Reduced inspection costs (more reliable) • Once programming, setup and verified the equipment can be operated by a less skilled operator.

  15. Disadvantages • Initial cost of CNC machine tools • Servicing of equipment • Larger machines require more space • Personnel must be trained in the programming and operation of this equipment.

  16. All videos Copywrite CNC Workshop Addison Wesley Longman 1999

  17. Definitions • FMS • Fixed Manufacturing Systems- An automated process that can not be reprogrammed. The system is most likely replaced. • Flexible Manufacturing System- An automated system that can be reprogrammed and broken apart to complete other tasks. This type of system is initially expensive but pays off in the long run.

  18. Definitions • NC - A method of accurately controlling the operation of a machine tool by a series of coded instructions, consisting of numbers, letters of the alphabet, and symbols that the machine control unit can understand. • MCU - Machine Control Unit - decodes NC codes to drive and monitor servo motor movements.

  19. Definitions • CAM Package: (Computer Aided Manufacturing) A software solution capable of generating NC code from assigned tool paths applied to part geometry. • Control Systems • Open loop system - servo motor driven by pulses without feed back encoders. • Closed loop system - servo motor is driven by electrical pulses. An encoder provides feedback to verify machine movements.

  20. Punched Paper Tape

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