HEIDENHAIN TNC 407 (280 580) ISO Programming - Manual (Page 28)

TNC 426/TNC 425/TNC 415 B/TNC 407 1-10
1 Introduction
1.2 Fundamentals of NC
Introduction
This chapter discusses the following topics:
• What is NC?
• The part program
• Programming
• Reference system
• Cartesian coordinate system
• Additional axes
• Polar coordinates
• Setting the pole
• Datum setting
• Absolute workpiece positions
• Incremental workpiece positions
• Programming tool movements
• Position encoders
• Reference marks
What is NC?
NC stands for Numerical Control, that is, the operation of a machine tool
by a series of coded instructions comprised of numbers. Modern controls
such as the TNC have a built-in computer for this purpose and are there-
fore called CNC (Computerized Numerical Control).
The part program
The part program is a complete list of instructions for machining a part.
It contains such information as the target position of a tool movement, the
path function (how the tool should move toward the target position) and
the feed rate. Information on the radius and length of the tool, spindle
speed and tool axis must also be included in the program.
Programming
ISO programming is partially dialog-guided. The programmer is free to
enter the individual commands (words) in each block in any sequence
(except with G90/G91). The commands are automatically sorted by the
TNC when the block is concluded.