CNC Programming
CNC Programming
Basics of NC Part Programming:
During secondary motion, either the tool moves relative to the workpiece or the workpiece moves relative to the tool. In NC programming, it is always assumed that the tool moves relative to the workpiece no matter what the real situation is.
The position of the tool is described by using a Cartesian coordinate system. If (0,0,0) position can be described by the operator, then it is called floating zero.
In defining the motion of the tool from one point to another, either absolute positioning mode or incremental positioning mode can be used.
1. Absolute positioning. In this mode, the desired target position of the tool for a particular move is given relative to the origin point of the program.
2. Incremental positioning. In this mode, the next target position for the tool is given relative to the current tool position.
CNC Programming
Manual
• Write code directly
Computer-assisted
• Draw cutter path
CAD/CAM (Computer Aided Design and Computer Aided Manufacture)
• Draw the part
• Cutter path is generated
CNC Programming
• Offline programming linked to CAD programs.
• Conversational programming by the operator.
• MDI ~ Manual Data Input.
• Manual Control using jog buttons or `electronic handwheel’.
• Word-Address Coding using standard G-codes and M-codes.
CNC
CNC
The term numerical control is a widely accepted and commonly used term in the machine tool industry. Numerical control (NC) enables an operator to communicate with machine tools through a series of numbers and symbols.
NC which quickly became Computer Numerical Control (CNC) has brought tremendous changes to the metalworking industry. New machine tools in CNC have enabled industry to consistently produce parts to accuracies undreamed of only a few years ago. The same part can be reproduced to the same degree of accuracy any number of times if the CNC program has been properly prepared and the computer properly programmed. The operating commands which control the machine tool are executed automatically with amazing speed, accuracy, efficiency, and repeatability.
The ever-increasing use of CNC in industry has created a need for personnel who are knowledgeable about and capable of preparing the programs which guide the machine tools to produce parts to the required shape and accuracy. With this in mind, the authors have prepared this textbook to take the mystery out of CNC – to put it into a logical sequence and express it in simple language that everyone can understand. The preparation of a program is explained in a logical step-by-step procedure, with practical examples to guide the student.
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