| Credit- Degree applicable | | Effective Quarter: Fall 2020 | I. Catalog Information
| DMT 84A | Introduction to CNC Programming and Operation; Mill | 5 Unit(s) |
| | (Formerly MCNC 75A.) Advisory: EWRT 200 and READ 200, or ESL 261, 262 and 263; MATH 210 or equivalent; DMT 80 or experience in machining processes. Lec Hrs: 36.00
Lab Hrs: 72.00
Out of Class Hrs: 72.00
Total Student Learning Hrs: 180.00 Introduction to mill tool path programming using G & M code format. CNC systems and components including machine controller functions and operations. Program entry, editing, and verification. Calculation for mill cutter compensation. Precision inspection techniques. Basic mill setups, including cutting tool selection, and work holding. |
| Student Learning Outcome Statements (SLO)
| | | Demonstrate the set up and basic operation of vertical machining centers. |
| | | Create basic word-address programs to successfully construct projects using vertical machining centers. |
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II. Course Objectives | A. | Describe three axis CNC milling machines. |
| B. | Select and calculate logical tool paths and positioning for mill cutters. |
| C. | Prepare basic three-axis programming for milling machine operations |
| D. | Operate mill CNC controller to download and dry run part programs |
| E. | Describe mill setup procedures for work piece and fixture offsets |
| F. | Apply the use of precision measuring tools to inspect the accuracy of machined parts |
| G. | Describe mill cutting tool materials; characteristics, and uses. |
| H. | Explain the common types and characteristics of CNC milling machine tooling. |
III. Essential Student Materials IV. Essential College Facilities | | CNC machine tool manufacturing lab. |
V. Expanded Description: Content and Form | A. | Describe three axis CNC milling machines. |
| 1. | CNC milling machine types and applications. |
| 2. | Numerical control components. |
| a. | Re-circulating ball screws. |
| b. | Pneumatic and hydraulic. |
| a. | One inch tape and floppy disks (historical reference). |
| b. | USB and direct file transfer |
| c. | Manual data input (MDI). |
| d. | Direct numerical control (DNC). |
| 5. | Controller programming formats. |
| a. | Word address, EIA/ISO standardized alphanumeric codes. |
| 6. | Mill axis and machine interpretation. |
| a. | Cartesian coordinate system. |
| 1. | X, Y, and Z axis designations. |
| 2. | A, B, and C rotary axis designations. |
| c. | Continuous path, contouring, linear and circular interpolation. |
| 7. | Methods of tool positioning. |
| a. | Cumulative (incremental). |
| B. | Select and calculate logical tool paths and positioning for mill cutters. |
| 1. | Effective rough, semi-finish and finish cuts for productivity and accuracy. |
| a. | Rules for depth calculation. |
| b. | Close tolerance and thin wall applications. |
| 2. | Climb and conventional milling. |
| 4. | RPM and feed rate guidelines/calculations. |
| 5. | Cutter path development. |
| 1. | X and Y for symmetrical and non-symmetrical parts. |
| 2. | Z locations and considerations. |
| b. | Mill cutter centerline calculations. |
| 1. | Right triangle laws: computing unknown sides and angles; conversion of minutes/seconds to decimal degrees and decimal degrees to minutes/seconds; scientific calculator operation. |
| 2. | Calculation of cutter compensation: definition of point, line, angle and arc; plot coordinate points for mill cutters (to form inside/outside square obtuse and oblique corners)(to form inside/outside corners with 90 degree arcs). |
| C. | Prepare basic three-axis programming for milling machine operations |
| 1. | CNC program preparation. |
| a. | Basic prepatory and miscellaneous functions. |
| b. | Speed, feed and tool address. |
| 1. | Circular interpolation: with I and J; with R. |
| 3. | Plunge milling methods: pre-drill; straight plunge or ramp. |
| d. | Canned cycles with R plane. |
| 2. | Peck drill (fixed pitch). |
| 4. | Use with L repeat command. |
| 1. | Climb/Conventional milling |
| g. | Incremental and absolute. |
| 2. | Verify CNC programs by means of machine simulators and software verification tools. |
| D. | Operate mill CNC controller to download and dry run part programs |
| 1. | Down load programs from PC or DNC. |
| 2. | Down load programs from floppy disk or USB |
| 3. | Review commonly used controller functions. |
| 4. | Use jog functions to accurately locate spindle. |
| 5. | Input and operate in MDI. |
| 6. | Call up and run programs in memory. |
| 7. | Run tool tryout with single block and adjusted feed rates. |
| E. | Describe mill setup procedures for work piece and fixture offsets |
| 1. | Workpiece/fixture alignment. |
| 2. | Workholding procedures for accuracy. |
| 3. | Location and setting of workpiece/fixture zero. |
| F. | Apply the use of precision measuring tools to inspect the accuracy of machined parts |
| 1. | Travel and test indicators. |
| c. | Selecting blocks to build-up |
| 3. | Sine bar set-ups for angles. |
| a. | Calculate block build-up for angles. |
| b. | Calculate error of measured angle. |
| G. | Describe mill cutting tool materials; characteristics, and uses. |
| 3. | Angles; relief and rake. |
| H. | Explain the common types and characteristics of CNC milling machine tooling. |
| a. | Tapers, methods of securing. |
| b. | Retention stubs, lengths. |
| 1. | End mill, set screw clamping. |
| 2. | Collet chucks, collet sizes. |
| 3. | Tapping: floating (tension/compression); rigid. |
| 5. | Adapters: Morse; Jacobs; boring head. |
VI. Assignments | A. | Lab projects demonstrating mastery of skills using three axis CNC machines, simulators and verification software covered in this course. |
| B. | Take home and in class worksheets involving feeds, speeds, and cartesian coordinate calculations. |
| C. | Reading from textbooks and references. |
VII. Methods of Instruction | | Lecture and visual aids
Discussion of assigned reading
Discussion and problem solving performed in class
Quiz and examination review performed in class
Laboratory discussion sessions and quizzes that evaluate the proceedings weekly laboratory exercises
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VIII. Methods of Evaluating Objectives | A. | Exams covering lecture and lab material relating to CNC machine tool programming and operation. Evaluation based on completeness and accuracy of word address programs and related CNC machine set-up and operation. |
| B. | Completion and accuracy of take home worksheets with emphasis on use of correct speed/feed formulas and coordinate calculations from drawings. |
| C. | Manufacturing rubric used to evaluate and inspect laboratory projects and exercises. |
| D. | A comprehensive, final exam that requires students to critically analyze and apply concepts examined throughout the course. |
IX. Texts and Supporting References | A. | Examples of Primary Texts and References |
| 1. | Schmid, Peter,"CNC Programming Handbook, Third Edition", New York, New York: Industial Press, 2008 |
| 2. | DMT Staff: "Design and Manufacturing Technologies 84A Syllabus" De Anza College, Cupertino, CA, 2018. |
| B. | Examples of Supporting Texts and References |
| 1. | Mattson, Mike: "CNC Programming Principles and Applications Second Edition", Albany, New York: Delmar Publishing, 2009 |
X. Lab Topics | A. | Multi - Axis CNC milling machine |
| B. | Word address programming |
| C. | CNC mill controller operations |
| D. | CNC mill set up procedures |
| E. | Measuring tools and Inspection |
| F. | CNC milling tooling (cutting tools and holders) |
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