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Credit- Degree applicable
Effective Quarter: Fall 2016

I. Catalog Information


DMT 84A
Introduction to Computer-Aided Numerical Control (CNC) Programming and Operation; Mills
5 Unit(s)
 

(Formerly MCNC 75A.)

Advisory: EWRT 200 and READ 200 (or LART 200), or ESL 261, 262 and 263; MATH 210 or equivalent; DMT 80 or experience in machining processes.

Three hours lecture, six hours laboratory (108 hours total per quarter).

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.


II. Course Objectives

A.Describe multi axis CNC milling machines.
B.Select and calculate logical path logic 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.Understand 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

 Scientific calculator

IV. Essential College Facilities

 Laboratory/classroom equipped with precision measuring tools, CNC machines, tooling, computers, peripherals and software

V. Expanded Description: Content and Form

A.Describe multi axis CNC milling machines.
1.CNC milling machine types and applications.
2.Numerical control components.
a.Computer.
b.Drive motor types.
c.Close loop systems.
d.Resolvers and encoders
3.Feed mechanism types.
a.Re-circulating ball screws.
b.Pneumatic and hydraulic.
4.Data mediums.
a.One inch tape and readers (historical reference).
b.Floppy disk and USB
c.Manual data input (MDI).
d.Direct numerical control (DNC).
5.Controller programming formats.
a.Word address, EIA/ISO standardized alphanumeric codes.
b.Conversational.
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.
b.Point to point.
c.Continuous path, contouring, linear and circular interpolation.
7.Methods of tool positioning.
a.Cumulative (incremental).
b.Coordinate (absolute).
B.Select and calculate logical path logic 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.
3.Pocket milling.
4.RPM and feed rate guidelines/calculations.
5.Cutter path development.
a.Zero point selection.
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.
c.Tool coordinates.
1.Circular interpolation: with I and J; with R.
2.Slotting.
3.Plunge milling methods: pre-drill; straight plunge or ramp.
4.Bolt hole circles.
d.Canned cycles with R plane.
1.Drill cycle.
2.Peck drill (fixed pitch).
3.Counterbore.
4.Use with L repeat command.
e.Tool length offset.
f.Cutter compensation.
1.Climb/Conventional milling
2.Ramp on/off moves
g.Incremental and absolute.
2.Verify CNC programs by means of solid model translator.
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.Understand the use of precision measuring tools to inspect the accuracy of machined parts
1.Travel and test indicators.
a.Parts, attachments.
b.Setups, cosine error.
2.Gage blocks
a.Classes
b.Care
c.Selecting blocks to build-up
d.Wringing
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.
1.Carbide
2.Coatings
3.Angles; relief and rake.
H.Explain the common types and characteristics of CNC milling machine tooling.
1.Tool holders.
a.Tapers, methods of securing.
b.Retention stubs, lengths.
c.Types.
1.End mill, set screw clamping.
2.Collet chucks, collet sizes.
3.Tapping: floating (tension/compression); rigid.
4.Stub arbors.
5.Adapters: Morse; Jacobs; boring head.
2.Workholding.
a.Vise and stop.
b.Strap and toe clamps.
c.Collet and V-blocks.

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

VIII. Methods of Evaluating Objectives

A.Two exams covering lecture material relating to safety, conventional machine tools and lab demonstrations of the three assigned lab projects.
B.Completion and accuracy of take home worksheets with emphasis on use of correct speed/feed formulas and coordinate calculations from drawings.
C.Evaluation and inspection of 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.MCNC Staff: "Manufacturing and CNC Syllabus 75A," De Anza College, Cupertino, CA, 2012.
B.Examples of Supporting Texts and References
1.Mattson, Mike: "CNC Programming Principles and Applications First 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)