Standard |
Rev.08/01/03
Provides a comprehensive introduction to computer numerical controlled (CNC) machining processes. Topics include: math review, safety, jigs and fixtures, tooling and tool holders, reference points, tool offset, program loading and editing, and safety.
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Competency Areas |
Hours
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Jigs and Fixtures |
Class |
6 |
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Tooling and Tool Holders |
D. Lab |
0 |
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Reference Points |
P. Lab/O.B.I. |
3 |
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Tool Offset |
Credit |
7 |
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Program Loading and Editing |
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Safety |
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Prerequisite: |
MCH 116 |
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Corequisite: |
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Course Guide |
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Competency |
After completing this
section, the student will: |
Hours |
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Class |
D.Lab |
P.Lab/ O.B.I. |
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JIGS AND FIXTURES |
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Theory |
Explain the differences between jigs and fixtures, list the advantages of each, and define the basic function of each. |
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Explain the qualities and features of a good fixture. |
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Design |
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Include type of holding device used to secure the jig or fixture to the table and the workpiece to the jig of fixture. |
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List the type of milling operation that is to be completed on each part. |
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Application |
Build a simple jig or fixture to hold a workpiece to mill a single feature. |
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TOOLING AND TOOL HOLDERS |
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Make a list of sound tooling practices which take into consideration cost of tools, speed and feeds, production time, surface quality and geometry of the tool. |
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Describe the overall impact of proper tooling on NC/CNC machines. |
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Explain how correct use of cutting tools and tool holders affects overall machine performance and productivity levels. |
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REFERENCE POINTS |
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Theory |
Explain the Cartesian coordinate system. |
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Define absolute and incremental dimensioning and control systems. |
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Explain how fixed and full floating zero systems work. |
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Programming |
Write simple CNC programs using both systems of dimensioning. |
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TOOL OFFSET
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Theory |
Define tool offset and the relationship between ID and OD operations. |
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Discuss the primary differences between random and sequential tooling. |
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Explain how tool offset is set on CNC machines. |
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Explain how varying differences in cutter diameters are compensated and programmed. |
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Determine how a turret machine with multiple cutting tools and operations can be programmed to compensate for various sized cutters. |
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Programming |
Write a program with a tool part that uses the center line aligned with the center of the cutter, left and right side of the cutter. |
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PROGRAM LOADING AND EDITING
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Theory and procedures |
Demonstrate loading tape programs, floppy disks and direct programming into the computer. |
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Explain the use of plotters to check and edit programs. |
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Program loading |
Load a program into a plotter and graph the movements of the plotter point. Check the measurements to determine the accuracy of the program. |
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Load a program into a CNC machine and use a pen and paper to check machine table movements. |
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Load a program by hand directly into the computer. Check by using the pen and pencil to check table movements. |
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SAFETY |
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Suggested Resources |
Baril, R. (1987). Modern machining technology. Albany, NY: Delmar.
Luggen, W. W. (1986). Introduction to NC-CNC operation. Englewood Cliffs, NJ: Prentice
Hall.
Machining metals handbook. (1989). Materials Park, OH: ASM International.
McMcGeough, J. A. (1988). Advanced methods of machining. New York: Routledge
Chapman & Hall.
Rizzo, L. (1985). CNC lathe. Garden City, NY: Bergwall.
Smith, G. T. (1989). Advanced machining. New York: Springer-Verlag.
Walker, J. R. (1989). Machining fundamentals. South Holland,
IL: Goodheart.