Terms used in CNC machining

Cycle Start:

The cycle start is a button that is used by the controller for the operation of the programs i.e., continues the previously stopped program or initiates the new program.

Cycle Stop:

The cycle stop is a button that is used by the controller for the operation of the program in the CNC machine, or pause the tool feed in this step, and simultaneously not stopping the spindle movement for the same.


Block Delete:

A predetermined series of program blocks are skipped by using the machine control. By using the block delete option we can run the same program with two versions.

Control panel:

The control panel is used to control the options of the CNC machine like ‘run the program’, ‘store’, ‘edit the commands’ given in the part programming, and also to control some other coordinates information.


CRT means cathode ray tube. The CRT acts as a main screen to display the information of the machine to the operator.


Dry running:

By using the dry running we can just perform trail option of the part programming, without using any parts and cutting fluid. It is also used to check the program.

Edit mode:

By using the Edit mode option we can edit the part program and store the program to those changes.

Emergency stop:

It is used to shut down all the machine function automatically.

Feed rate override

During the operation the override allows the operator to adjust the feed rates of the tool. It functions as the programmed value in the percentage.

Handle mode:

By using the handle mode function the operator must adjust the tool movement with the help of the handle wheel. In some machines they must combine with jog or handle mode.

Jog mode:

By using the jog mode function the operator must adjust the tool movement with the help of the jog button.in some machines they must combine with jog and handle mode.

Machine panel:

By using the machine panel the CNC machine must guide the tool movement directly and also the machine components operation.

Machine Zero:

The positions are located at the positive direction of X, Y, Z axis, and the position must be set permanently for each individual CNC machine.

Manual data Input Mode:

By using the manual data input mode, it allows the operator to enter and execute the blocks programming code manually at the control panel.

 Memory Mode:

The stored part program in the machine must be allowed by the operator to call up and execute.


The micrometer is a hand held measuring device used to inspect the dimensions of the parts. They measure an accurate value of nearly 0.001 inches or in meters i.e., 0.02 mm.


The mode is used to start the machine and determine the way it executes manual or automatic commands.

Optional Stop:

If we select the optional stop on the machine then the program is paused. By using the optional stop we can inspect the machine in between the operations.


During the operation by using the override option we can adjust the feed rate and the speed of the operation.

Part program:

Programmer is responsible for the construction of the part program. The part program is used to translate the work piece design into the program instruction for the CNC machine.

Proving out:

The proving out option is used to check the accuracy and the proper tool setup.

Rapid feed rate override:

During the operation the override is used to reduce the rapid tool movement rate. The rapid rate must be 25% of the original rate or a smaller amount.

Rapid Mode:

The rapid mode is used to allow the manual movement of the components in the machine at the time of high travel rates.

Single block mode:

The single block mode is used to allow the operator, and execute the part program at a time on the single block. For executing each block the operator must push the start button.

Soft key:

By using the soft key one can execute different commands. The key purpose depends on the CRT display.

Spindle speed override:

By using the spindle speed override we can adjust the spindle speed during the operation.


The undesirable but then adequate deviance from a preferred dimension is known as tolerance.

Tool offset:

The stored valve should be compensated for variations in tool lengths. The tools must require an offset and they are measured from the spindle position or turret.

Zero return:

The zero returns are controls automatically locates the spindle or turret in the machine zero position.

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