CNC Programming & Machining — Comprehensive Notes

Course Synopsis and Topics

• The course aims to provide knowledge about CNC programming and the skills to operate CNC machines, enabling effective performance whether individually or in teams.
• Topics covered include:
  • CNC milling & turning
  • Process planning
  • Programming for CNC Milling
  • Programming for CNC Turning
  • EDM Wirecut
• Course structure emphasizes both theory and practical lab work to develop practical capabilities in CNC programming and machining.

Course Learning Outcomes (CLO)

• CLO 1: Apply the knowledge of CNC machine tools and CNC tool path programming to related manufacturing technology systems. (PLO1, C3)
• CLO 2: Follow the appropriate practical method from setting up the machine parameters until execution of the program. (PLO5, P3)
• CLO 3: Display the ability to lead a specific task individually or in group within the allocated time. (PLO9, A5)

Assessments

• Theory Test 1 (10%) - UNIT 1, 2 & 3
• Theory Test 2 (10%) - UNIT 4, 5 & 6
• Final Examination (30%) - UNIT 3, 4, 5, 6, 7, 8 & 9
• Practical (30%) – 3 lab
• Project (10%) – 1 project
• Project (10%) - Affective

Chapter Structure (Course Contents)

• CHAPTER 1 – INTRODUCTION
• CHAPTER 2 - CNC MILLING & CNC TURNING
• CHAPTER 3 - NUMERICAL CONTROL SYSTEMS
• CHAPTER 4 - PROCESS PLANNING AND CUTTING TOOL SELECTION
• CHAPTER 5 - TOOL CHANGING AND TOOL REGISTERS
• CHAPTER 6 - CNC PROGRAMMING - MILLING (1)
• CHAPTER 7 - CNC PROGRAMMING - MILLING (2)
• CHAPTER 8 - CNC PROGRAMMING - TURNING
• CHAPTER 9 - CNC PROGRAMMING - EDM WIRECUT

References

• SEDMON MANUFACTURING Engineering and Technology, Seventh Edition, Serope Kalpan, Steven R. Snid, PEARSON
• CNC PROGRAMMING HANDBOOK, Michael Fitzpatrick
• Machining and CNC Technology, PETER SMID
• Precision Machining TECHNOLOGY, Second Edition
• COMPUTER NUMERICAL CONTROL Concepts & Programming, 4OTION
• Haas Factory Outlet – Lathe Series Training Manual
• Haas CNC Lathe Programming – Haas Factory Outlet (A Division of Prodacty)
• Haas CNC Mill Programming – Haas Factory Outlet
• NIMS (Peter Hoffman, Eric Hopewell, Brian Jans, Warren Seames)

Chapter 1: Introduction

• 1.1 NC and CNC Technology
• 1.2 Conventional and CNC Machining
• 1.3 Types of CNC Machine Tools
• 1.4 Personnel for CNC
• 1.5 Safety and Maintenance

Unit Objectives (Chapter 1)

• After completing the unit, students should be able to:
  • Explain numerical control.
  • Describe the difference between a conventional machine and a CNC machine.
  • Identify the types of CNC Machine Tools.
  • Explain the personnel for CNC.
  • List the safety and maintenance related to CNC.

1. Introduction to Numerical Control (NC) and CNC

• Numerical Control (NC) technology emerged in the mid-20th century.
• Key origin: 1952, U.S. Air Force and MIT in Cambridge, MA, with John T. Parsons (1913-2007) associated with NC.
• Production manufacturing adoption: early 1960s.
• The CNC boom: around 1972, followed by affordable microcomputers in the following decade.
• History and development are well documented in publications.

1.1 Numerical Control (NC) and CNC Technology

• Definitions:
  • NC: Operation of machine tools by means of specifically coded instructions to the machine control system.
  • CNC: Generated by merging the computer with numerical control; uses a computer to provide the data needed for a part via a part program or CNC program.
• Basic components:
  • NC/CNC Program: set of instructions stored for future use to achieve identical machining results.
  • Program can be stored and used repeatedly for consistent results.
• Key distinction:
  • NC uses fixed, built-in logical functions inside the control unit; cannot easily change the program at the control.
  • CNC uses an internal microprocessor with memory to store routines; programmers/operators can modify programs at the control with instantaneous results.
• Memory and storage:
  • NC often used punched tapes/cards; CNC stores programs as software in memory chips.
• Practical implication:
  • CNC enables greater flexibility and adaptability in manufacturing due to software-based control.

1.1.1 NC and CNC Technology: NC vs CNC comparison

• NC and CNC definitions restated for clarity.
• Input methods:
  • NC: punched tapes and punch cards; keyboards in some cases.
  • CNC: digital memory and software; easier parameter alteration.
• Parameter alteration:
  • NC: alteration in operation parameters is generally not possible at the control.
  • CNC: alteration in operation parameters is possible at the control.
• Memory/storage:
  • NC: typically no memory for storing instructions.
  • CNC: memory exists to store instructions.
• Cost and maintenance:
  • NC: less expensive; lower maintenance costs.
  • CNC: highly expensive; higher maintenance costs.
• Skill requirements:
  • NC: highly skilled operators required.
  • CNC: less skilled operators required.
• Flexibility:
  • NC: less flexible.
  • CNC: more flexible.

1.2 Conventional vs CNC Machining

• Conventional Machining:
  • Operator-directed; uses manual control via levers, buttons, wheels to set tool path and machine parameters.
  • Gear shifting for speed, tool changing, feeding performed manually.
• CNC Machining:
  • Managed by pre-programmed computer designations; tools may not require direct contact with raw material.
• Key contrasts:
  • Conventional: manual setup and operation; variability between operators and batches; higher risk of human error.
  • CNC: programmable, repeatable results; potential for complex geometry; higher consistency.

1.2 Practical Differences and Considerations

• Conventional advantages and limitations:
  • Simplicity for simple or one-time jobs.
  • Manual operation can be faster for simple tasks but less repeatable.
• CNC advantages and limitations:
  • Repeats identical results once a program is proven.
  • Suitable for complex parts; may not always be the most efficient for simple one-off tasks.
• Overall comparison: both approaches produce high-quality parts; differences lie in programing ease, storage, flexibility, tolerance, and repeatability.

1.3 Types of CNC Machine Tools

• List of CNC machine tools:
  • Mills and Machining Centres
  • Lathes and Turning Centres
  • Drilling machines
  • Boring mills and Profilers
  • EDM wire machines
  • Punch presses and Shears
  • Flame cutting machines
  • Routers
  • Water jet and Laser profilers
  • Cylindrical grinders
  • Welding machines
  • Benders, Winding and Spinning machines
• Example machine brands and configurations appear in visuals (e.g., 875-5AX, FANUC, MultiCam).

1.3 Examples of CNC Machines

• Examples shown include:
  • CNC Lathe: clamps workpiece, rotates on spindle, tools shape the workpiece; used for symmetrical objects (spheres, cones, cylinders).
  • CNC Milling: high-precision ball screws move to programmed coordinates; multiple axes available.
  • CNC Laser Cutting: cutting via laser; program send instructions to laser cutter.
  • CNC Plasma Cutting: cutting via accelerated plasma jet through conductive materials.
• EDM (Electrical Discharge Machining) details later in 1.4.

1.4 Personnel for CNC

• Core roles:
  • CNC Programmer: responsible for problems related to CNC operations; reads technical drawings; visualizes tool motions; analyzes and integrates data into a safe part program; determines manufacturing methodology; needs mathematical understanding for arc angles and equations.
  • CNC Machinist/Operator: handles setup and actual machining; can be integrated with programmer role in small shops; ensures program feasibility and machine readiness.
• Typical organizational structure varies by company size and product, but distinct roles usually exist.
• Personnel responsibilities (summary from examples):
  • CAD/CAM and software skills
  • Reading drawings and understanding engineering intent
  • Tool selection, jig/fixture design and fabrication
  • First article inspection and test cuts
  • Troubleshooting, maintenance, and change control
  • Knowledge of G- and M-codes and CAM integration
• Salary and job description samples (illustrative):
  • Programmer profiles with ranges such as Junior, Average, Senior wages; examples in MYR with ranges provided (e.g., MYR 2,900 - 4,060 per month, etc.)
• Example job postings (illustrative):
  • CNC Programmer roles requiring: programming, setting up, operating CNC turning/milling; reading drawings; process engineering involvement; training machinists; fixture design; trouble-shooting; change control; project improvement; training responsibilities.

1.4 CNC Programmer: Expanded Responsibilities and Background

• Core responsibilities:
  • Programming of CNC machines
  • Defining how to optimize machining of different components
• Background and skills:
  • Academic degree in engineering, mathematics, or computer science
  • Strong knowledge of M- and G-codes
  • CAD and manufacturing software proficiency
• Salary exemplars (illustrative):
  • Junior: 60{,}000 per year
  • Average: 75{,}000 per year
  • Senior: 100{,}000 per year
• Example company profiles and job postings illustrate real-world expectations for CNC programmers.

1.4 CNC Programmer: Example Roles (Illustrative Job Postings)

• Bend Weld Engineering (M) Sdn Bhd (Pontian, Malaysia):
  • Responsibilities include: programming, setup, operation, manufacturing processes; first article inspection; jig/fixture design; training machinists; training and problem solving; project improvements.
• RICHSUN PRECISION ENGINEERING (M) Sdn. Bhd. (Johor):
  • Responsibilities include: translating drawings into CAM programs; operating Fanuc CNC machines; selecting feeds/speeds; preparation of setup sheets; defect investigations; technical support for daily processes.
• Other examples include roles for turning and milling; tool changes and process optimization responsibilities listed.

1.4 CNC Machine Operator and CNC Machinist

• Roles may be combined in smaller shops; key responsibilities:
  • Tool and machine setup; part handling and in-process inspection; reporting findings to programmers; ensuring quality and safety; understanding limitations of programs.
• Typical duties include:
  • Setting up, operating, inspecting parts, and maintaining equipment and records
  • Reading schematics and blueprints; maintaining documentation such as job completion lists
  • Ensuring proper operation of drills, lathes, and milling equipment
  • Ensuring proper software/hardware integration and program integrity
• Examples of job postings illustrate wage ranges (e.g., MYR 1,300 - 4,000 depending on role and experience).

1.5 Safety and Maintenance

• Safety is the most important element in programming, setup, machining, tooling, fixturing, inspection, shipping, and any operation in a machine shop.
• Hazards: mechanical and electrical hazards; sharp cutting tools and chips; moving machinery.
• A clean work area prevents accidents (no chips/oil spills on the floor); avoid loose clothing, jewelry, ties, scarves, unprotected long hair; avoid improper glove use.

1.5.1 Safety Awareness

• CNC machines are generally safer due to enclosed designs, reducing risk of flying chips, debris, or contact with spinning tools.
• However, shop environments remain dangerous; chips are sharp; eye injuries can occur from chips; chips can reach skin; machines can move quickly; contact with a spinning tool is dangerous.
• Examples of safety failures that caused injuries:
  • Not wearing safety glasses leading to eye injury from flying chips.
  • Leaning on benches with chips on the floor causing cuts.
  • Wearing open sandals leading to foot injuries from falling chips.
  • Leaning into a machine leading to contact with stored tools and severe cuts.
  • Reaching into a machine and getting cut by an end mill.
  • Grinding aluminum on a bench grinder with a wheel that can shed embedded debris.

1.5.2 Personal Conduct & Shop Etiquette

• Follow strict rules of personal conduct and etiquette:
  • Be aware of hand positioning and potential slip hazards.
  • Do not interrupt someone operating a machine.
  • Clean up after yourself; leave work area clean and tools in their place.

1.5.3 Shop Clothing

• Dress rules for safety:
  • Wear safety glasses (with side shields) at all times in the shop.
  • Use hearing protection for loud operations.
  • Do not wear long sleeve shirts that could get caught.
  • Remove rings and watches when at the machine.
  • Do not wear gloves while operating machines; latex gloves may be acceptable in some contexts.

1.5.4 General Safety Practices

• Safe workplace rules:
  • Do not operate equipment without proper training.
  • Do not tamper with machine safety guards or switches.
  • Handle cutting tools with care; never by the cutting flutes.
  • Use a brush to clean chips; never use hands or rags to remove chips.
  • Ensure work area is clear before starting; never start or jog the machine until setup is verified.

1.5.4 (continued) General Safety Practices (Additional Rules)

• Additional cautions for starting and tool changes:
  • Do not start until the setup can safely withstand cutting forces.
  • Know the location of emergency stop and practice its use.
  • Position the part near the operator at the end of the program to avoid leaning into the machine.
  • Avoid coolant contact; water-based coolant can harbor microbes.

1.5.5 CNC Safety Practices for First Runs

• Use rapid and feed override controls to slow down the machine for initial testing.
• Incorrect tool or fixture offsets are a major cause of crashes; pay attention to moves at the start of the program and after tool changes.
• Use single-block mode to advance line-by-line until the tool reaches cutting depth.
• Stay at the machine with a hand near the emergency stop button.
• Stop machine motion at the first sign of trouble.

1.5.6 Maintenance

• Daily/Preventive maintenance checks and procedures:
  • At the start of each opportunity to work on any turning or machining center, verify lubrication reservoirs are filled with the correct oils as specified in manuals.
  • Modern CNC machines have sensors to prevent operation when oil levels are too low.
  • Check pneumatic (air) pressures and regulate properly; insufficient pressure may disable functions.
  • Check coolant tank level and mixture; a site glass is used for viewing.
  • Check and adjust coolant pH level routinely with a refractometer; adjust mixture to prevent bacterial growth; use water-soluble coolant mix or synthetic coolant or cutting oil; clean and refill coolant tank periodically.
  • Clean the machine thoroughly when many chips are present; exterior surfaces may need only wiping.
  • Clean ways and working envelope with coolant to wash the table and guards; chips can be removed with a wet/dry vacuum; avoid using compressed air to blow chips away from ways as it can push chips behind guards and worsen micro-switch issues.

Common Daily Maintenance Practices

• Verify lubrication reservoirs are filled; verify air pressure via regulator.
• Check chip pan, coolant level, and mixture; keep work area clean.
• Ensure automatic chip removal equipment is operational when cutting metal.
• Ensure worktable and mating surfaces are clean and free from nicks or burrs.
• Check chuck pressure settings to ensure proper clamping.
• At end of use, clean machine with wet/dry vacuum or wash guards with coolant to remove chips.

Daily Preventive Maintenance (DPM) Checklist (Sample)

• Responsibility: Production staff
• Checkpoints include:
  • Lubrication system oil level (Month, Machine, etc.) with inspection methods: visually or actual value entries
  • Hydraulic oil level with actual value
  • Coolant oil level with actual value
  • Clamping pressure of chuck with actual value
  • Check machine guards and panel doors in position
  • Check for abnormal sounds and oil/coolant leakages
  • Check for tightness of cutting tools and holders
  • Cleanliness of slideways
  • Clean waste oil collection box and coolant collection points
  • Check air conditioning and coolant filtration and overall machine cleanliness
• Documentation includes signatures (Operator, In-charge) and approvers; example form named VSPLCNCDPMCL_001-00 with a structured check schedule

1.5.6 Maintenance (Additional Notes)

• Focus on lubrication, hydraulic oil, coolant levels, and cleanliness; emphasize sensor-based protection in modern machines.
• Emphasize routine checks before operations and during daily usage to prevent unexpected failures.

1.6 Safety Posters and Housekeeping Reminders

• Safety posters and house rules emphasize:
  • No unauthorized access to rooms and cupboards
  • No running or fooling around during practical work
  • Do not climb, sit, stand, walk, ride, or touch conveyors
  • Do not perform maintenance on conveyors without lockout/tagout
  • Keep tools and equipment away when not in use; tidy as you go
  • Wear goggles; ensure safety gear is used when asked by the instructor
  • Report injuries to the teacher
  • Keep work areas tidy and free of spills; ensure all controls and stop/start mechanisms are visible and accessible
  • Understand location and function of all stop and start controls and emergency stops

1.7 Final Notes and Next Steps

• The document ends with a prompt to continue to the next class; students should reflect on the safety rules and maintenance practices introduced before moving forward.

Quick Reference: Key Concepts Summary

• NC vs CNC: definitions, input methods, memory/storage, cost, skill requirements, and flexibility
• Conventional vs CNC Machining: manual control vs programmable control; pros and cons
• Types of CNC Machines: mills, lathes, drilling, boring, EDM, plasma, laser, waterjet, routers, and more
• CNC Programming Roles: Programmer vs Operator/Machinist; combined roles common in small shops
• Safety and Maintenance: essential practices for safe operation, personal conduct, PPE, and preventive maintenance
• Daily Maintenance: lubrication, coolant, air pressure, cleanliness, and inspection routines
• Documentation: daily checks, signature sign-offs, and preventive maintenance records
• Real-world relevance and ethical implications: responsibility for safety, continuous improvement, training, and process reliability

Equations and Formulas (LaTeX)

• There are no explicit numerical formulas or engineering equations in the transcript. Where pricing or percentages appear, they are provided in percentage form for assessment weights: 10\%, 30\%, 30\%, 10\%, and so on.

Connections to Foundational Principles

• The material connects to foundational manufacturing principles: standardization, repeatability, and process control; the shift from manual to automated, programmable processes; safety culture as a core component of engineering practice; and the integration of CAD/CAM with CNC tooling for efficient production.

Real-World Relevance and Implications

• The content reflects industry expectations for CNC literacy, including the ability to read drawings, program tools, select processes, and maintain machines.
• Emphasizes the importance of safety, housekeeping, and continuous improvement in a machine shop environment.
• Illustrates how CNC technology enables higher consistency, complex geometries, and efficient production, while also requiring specialized skills and ongoing maintenance.

Ethical and Practical Considerations

• Safety culture and proper PPE usage protect workers and reduce liability.
• Responsible handling of tools, machines, and maintenance records supports quality and reliability.
• Training and ongoing skill development are essential due to evolving technology and software in CNC environments.

End of Notes