2 Operation
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2.2 Program Editing
2.2.1 Programming Overview
2.2.1.1. Part Programs
Prior to part machining, the part shape and machining conditions must be converted to a
program. This program is called a part program. A comprehensive machining plan is
required for writing the part program. The following factors must be taken into account
when developing the machining plan:
1. Determine the machining range requirements and select a suitable machine.
2. Determine the work-piece loading method and select the appropriate tools and
chucks.
3. Determine the machining sequence and tool path.
4. Determine the machining conditions, such as the spindle speed (S), feed rate (F),
coolant, etc.
A part program is a group of sequential commands formulated according to a part diagram,
machining plan, and command code of the numerical control unit. It is used to plan the tool
path with the assistance of the auxiliary functions of the machine. The part program can be
transmitted to the memory of the control unit via a PC, punched paper tape, or keyboard.
2.2.1.2. Programming Methods
A numerical control unit executes actions exactly in accordance with the commands of
the part program. So, programming is very important for numerical control machining.
There are two ways to design a CNC part program and they are briefly described in the
following:
1. Good capability of reading part diagrams.
2. Rich experience in machining processes.
3. Familiar with the functionality, operation procedure and programming language of
the machine.
4. Basic capability in geometric, trigonometric, and algebraic operations.
5. Good capability of determination of machining conditions.
6. Good capability in setting chucks.
7. Good capability in determination of part material.
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