HEIDENHAIN TNC 407 (280 580) User Manual - Manual (Page 11)

TNC 425/TNC 415 B/TNC 407 1-10
1 Introduction
1.2 Fundamentals of Numerical Control (NC)
Introduction
This chapter covers the following points:
• What is NC?
• The part program
• Conversational programming
• Reference system
• Cartesian coordinate system
• Additional axes
• Polar coordinates
• Setting a pole at a circle center (CC)
• 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, control of a machine tool by
means of numbers. Modern controls such as the TNC have a built-in
computer for this purpose and are therefore called CNC (Computerized
Numerical Control).
The part program
The part program is a complete list of instructions for machining a part.
It contains, for example, 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 given in the program.
Conversational programming
Conversational programming is an especially easy method of writing
and editing part programs. From the very beginning, the TNCs from
HEIDENHAIN were developed specifically for shop-floor programming
by the machinist. This is why they are called TNC, or “Touch Numerical
Controls.”
You begin programming each machining step by simply pressing a key.
The control then asks for all the information that it needs to execute the
step. It points out programming errors that it recognizes.
In addition to conversational programming, you can also program the TNC
in ISO format or transfer programs from a central host computer for DNC
operation.