HEIDENHAIN TNC 360 ISO Programming - Manual (Page 23)

TNC 360 1-6
1 Introduction
1.2 Fundamentals of Numerical Control (NC)
Introduction
This chapter addresses 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 mark evaluation
What is NC?
NC stands for Numerical Control. Simply put, numerical control is the
operation of a machine by means of coded instructions. Modern controls
such as the HEIDENHAIN TNCs have a built-in computer for this purpose.
Such a control is therefore also called a CNC (Computer Numerical
Control).
The part program
A part program is a complete list of instructions for machining a work-
piece. It contains such information as the target position of a tool move-
ment, the tool path — i.e. how the tool should move towards the target
position — and the feed rate. The program must also contain information
on the radius and length of the tools, the spindle speed and the tool axis.
Programming
The TNC is programmed in the ISO format; some programming sections,
however, are guided by dialog prompting. The single commands (words)
can be entered in any sequence within a block (except G90/G91). The TNC
automatically sorts the single commands as soon as the block is conclud-
ed.