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BMFS 3373 CNC TECHNOLOGY Lecture 11

BMFS 3373 CNC TECHNOLOGY Lecture 11. Modern Developments in the Process of CNC Programming. In the past: P rogramming was done manually, written in word address and tailored to specific controller. Trigonometry was one of the fundamental knowledge in calculating the tool path.

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BMFS 3373 CNC TECHNOLOGY Lecture 11

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  1. BMFS 3373CNC TECHNOLOGYLecture 11

  2. Modern Developments in the Process of CNC Programming In the past: • Programming was done manually, written in word address and tailored to specific controller. • Trigonometry was one of the fundamental knowledge in calculating the tool path. • The CNC machine needed to be halted during the program key-in process into the MCU. • Program verification was a must, that leads to machining and inspecting a test part first before a full run. And that soon changes with the coming of the digital age.

  3. Modern Developments in the Process of CNC Programming Using off-line computer to write and store part program, it creates an optimum condition when running a part program.

  4. Modern Developments in the Process of CNC Programming Introduction of Computer Aided Programming Languages: • The CNC controller can only function with word address codes with specific format acceptable to that specified controller. Trigonometric computation is also required. • A computer aided programming language tries to address some of these issues by allowing the program to be written using English-like command. • Furthemore, a program known as postprocessor allows the translation of this computer aided programming languages to word address program for all suits of controller. • The most popular computer aided programming language in use today is Automatically Programmed Tool (APT)

  5. Modern Developments in the Process of CNC Programming • APT is short for Automatically Programmed Tools. It was the first and still is the most powerful computer programming language. • APT can used to program the machining of complex surfaces on four- and five-axis machining centers, though it was originally restricted to run on large mainframe computers. • Advances in microprocessor technology have allowed it to be available on workstations and personal computers.

  6. Modern Developments in the Process of CNC Programming

  7. An Introduction to CAD/CAM • CAD/CAM stands for Computer-Aided Design and Computer-Aided Manufacturing. • CAD/CAM approach is superior to the technique of using computer aided programming language in preparing a part program • Some of the advantages of using CAD/CAM are: • The system can be used to check the program off-line. Resulting tool paths can be graphically displayed on the computer screen, and the user can zoom in and view the tool paths at various orientations. The system can generate real-time material removal simulations and flag tool breakthrough or part violation problems. • Time and cost of machining the part can be quickly determined. • The system can determine optimum tooling, speeds, and feeds for the material selected.

  8. An Introduction to CAD/CAM The element comprising a CAD/CAM approach in creating a part program is as followed: • A CAM file is created. • The CAD model is sent to the CAM file for machining. • The portion of the model to be machined is identified by the operator. • The start point for the machining is also input. • The tool to be used is identified. Tool speeds and feeds are input. • A postprocessor file for a particular CNC machine controller is recalled from the computer’s memory. • The CAM file is retrieved and post-processed into a word address program file acceptable to the machine controller. • The word address program can then be played back for editing. Upon playback the computer can display all resulting tool paths. • The tool paths can be zoomed, viewed or simulated at any angle.

  9. An Introduction to CAD/CAM The CAD/CAM approach to part programming

  10. End Chapter 11

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