HEIDENHAIN TNC 360 User Manual - Manual (Page 24)

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
• Conversational programming
• Cartesian coordinate system
• Additional axes
• Polar coordinates
• Setting a pole at a circle center (CC)
• Datum setting
• Absolute 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.
Conversational programming
Conversational programming is a particularly easy way of writing and
editing part programs. From the very beginning, HEIDENHAIN numerical
controls were designed for the machinist who keys in his programs
directly at the machine. This is why they are called TNCs, or "Touch
Numerical Controls."
You begin programming each machining step by simply pressing a key.
The control then asks for all further information required to execute the
step. You can also program the TNC in ISO format or download programs
from a central host computer for DNC operation.