Machinery's Handbook, 31st Edition
CNC PROGRAMMING
1355
Table clamp: Shows current status of table clamping. Coolant switch: Coolant control ON / OFF / AUTO. Gear selection: Shows current status of working gear range selection. Spindle rotation: Spindle rotation direction indicator (CW or CCW). Spindle orientation: Manual spindle orientation. Tool change: Switch allowing a manual tool change. Reference position: Switches and lights relating to machine zero position (HOME). Tailstock switch: Tailstock and/or quill switch to manually position tailstock. Index table switch: Manually indexes machine table during setup. M-S-T lock: Disables machine, spindle, and tool functions in the program. Machine lock: Disables all machine motions. Manual absolute: Coordinate system update on/off. Z-axis neglect: Milling Z-axis can be turned off during program verification. MDI mode: Manual Data Input mode. AUTO mode: Allows automatic operations. MEMORY mode: Allows program execution from memory of the CNC unit. DNC mode: Allows program execution from an external device. EDIT mode: Allows changes to programs stored in the CNC memory. MANUAL mode: Allows manual operations during setup. HOME mode: Allows manual return to machine zero. HANDLE mode: Manual Pulse Generator (MPG) for manual axis movement. JOG mode: Selects the jog mode for setup (manual feed rate motion). RAPID mode: Selects the rapid mode for setup. Memory access: Key (switch) to allow program editing. Lube light: Indicates low level of slide lubrication. Error lights: Red light indicating an error. Optional stop and block skip: Switches function only if the part program supports their use. For optional stop, part program must contain M01 function, and for block skip, the slash (/) symbol. Manual Data Input (MDI): This is a feature of the control panel that allows quick entry of program data. An operating mode can be selected as MDI, which allows program data to be entered by the machine operator. MDI is not intended to enter complete machining programs, but allows the operator a great deal of flexibility during setup. Typical applications include position data for setup, tool motion to a given location, machine functions control, even some special settings of machine parameters. Knowledge of basic programming principles in necessary, as MDI requires the use of normal programming methods. CNC Program Data The program data is a collection of all the program entries that will be accepted by the CNC system. Although the basic program principles are the same, the actual methods of inputting will always vary to a certain extent with different control models. Program Structure.— A CNC program structure is a method of developing a part pro gram that is well designed and written. This means that the program should be easy to read on paper or computer screen and written in a consistent manner. Program initialization should be logical; repetition of any tool should be made easy (without manual interaction); it should include important comments; and be as short as possible. A part program should always be designed with the machine operator in mind. Comments and Messages: Various comments and other messages can be included in the program, provided they are enclosed with a single set of matching parentheses. An abundance of comments may strain the CNC memory, but when used in moderation,
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