CNC Programming Basics Quiz

Control Numerical (CN) Definition

• CN is a programmable automation method
• Instructions (programs) control machine actions and movements
• Suitable for low to medium production volumes
• Easier to write new programs than modify existing equipment

Basic Elements of a CN System

• Program: Set of instructions to guide the processing equipment, written in a specific language (code).
• Control unit (CN): Interprets instructions from the program, converting them into signals that operate the machine devices.
• Processing equipment: Performs the actual work; includes worktables, machine tools, and motors/controls for their movement.

Classification of Numerical Controls

• Reference System: Fixed or floating
• Trajectory Control: Point-to-point or continuous
• Actuation Type: Hydraulic, electric, or pneumatic
• Control Loop: Open or closed
• Control Technique: Numerical Control (CN) Hardware, Computerized Numerical Control (CNC) Software, and Adaptive Numerical Control (CNA)

Characteristics of a CN Machine Tool

• Positioning mechanisms: Actuators (motors, valves, etc.) and control systems (open or closed loop)
• Measurement systems: Sensors (induction, photoelectric, etc.)
• Machine design: Precision and repeatability, chip removal systems
• Tool changing mechanisms: Turrets, tool magazines
• Control techniques: CN, CNC, and CNA

When is CN Applicable?

• Low to mid-volume production
• Complex part geometry
• Frequent design changes
• High precision and reliability requirements
• High production costs for part failures
• 100% inspection requirement

Types of Programming

• Manual Programming: Calculating trajectories manually, entering code on a console or PC
• Computer-Aided Programming (Pseudo-aided): CAD drawings to define points and manual operation using a console or PC
• Computer-Assisted Programming (CAM): CAD drawings generate trajectories, automatic calculation, collision detection, process simulation

Manual Programming Steps

• Analyze the part drawing (dimensions, tolerances, finishes, materials)
• Define elementary operations and their order
• Calculate each operation's trajectories and path
• Select appropriate machines and operation sequence
• Choose appropriate tool for each operation

Programming Results (Steps 1-5)

• Analyzing part drawing
• Defining elementary operations
• Calculating trajectories
• Selecting machines and operations
• Selecting tools

Programming Definition (Step 6)

• Following an ISO standard
• Coding the program

Programming Tests and Execution (Steps 7-8)

• Testing: Simulation in software, testing on soft material, verifying Z-axis corrections
• Execution: Block-by-block execution, overseeing each operation before proceeding, automatic execution (normal operation).

Stages in CNC Processing

• Preparation Stages: Planning the work and setting the data for the program
• Programming Stage: Creating and testing the programs for the machine to execute
• Adjustment Stage: Adjusting the machine to the program
• Ordering Launch Stage: Sending the program to be processed on the machine

Axes and Coordinate Systems

• Z-axis: Principal spindle axis. Indicating positive direction away from the part or in a consistent direction depending on the machinery.
• X-axis: Generally horizontal axis, dependent on the orientation of the Z-axis.
• Y-axis: Generally horizontal axis, perpendicular to the X and Z axes forming a right-handed coordinate system.
• Auxiliary Axes: Other axes (U, V, W) that are parallel to the principal axes or axes of rotational movement (A, B, C).

Points of Reference

• Machine Zero (M): Coordinate origin relative to the machine. Standardized according to machine axes.
• Machine Reference Point (R): Reference point for tool changes.
• Part Zero (W): Reference point on the part. Freely chosen by the programmer.
• Tool Adjustment Point (E): Specific point on the cutting tool used to calculate movements and compensate for tool wear.

ISO Programming Language

• Header (Program identifier, part information, process details).
• Program Body (Program steps, numerical instructions, and parameters, comments and function calls, etc.)
• End of Program Section.

Numerical Control Parameter Programming

• Programming Parameters: Quantities defining the machine tool settings.
• Variable parameters
• Numerical Constants

CNC Coordinate Systems

• Absolute positioning
• Incremental positioning

Control Numerical System

• Point-to-Point System
• Paraxial System
• Contouring System

CNC Programming

• Formatting
• Data Entry
• Verification
• Execution