HEIDENHAIN TNC 406 - Manual (Page 63)

42 4 Programming: Fundamentals, Files, Program Entry, Spark Erosion, Erosion Tables
4.1 F
u
ndamentals of P
o
sitioning
4.1 Fundamentals of Positioning
Introduction
This chapter covers the following topics:
„ What is NC?
„ The part program
„ Programming
„
Position encoders and reference marks
„
Reference system
„ Reference system with electrical discharge machines (EDM)
„ Programming electrode movement
„ Polar coordinates
„
Absolute and incremental workpiece positions
„
Setting the datum
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 TNCs 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 such information as the target position of an electrode
movement, the path function (how the electrode should move toward
the target position) and the feed rate.
Information on the radius and length of the electrode and the electrode
axis must also be included in the program.
Programming
Conversational programming is a particularly easy method of writing
and editing part programs.
HEIDENHAIN NCs were developed specifically for the machine
operator who keys in programs right at the machine. This is why they
are called TNC (Touch Numerical Control).
You begin each machining step by pressing a key. The TNC then asks
you for all the information it needs to execute the step.