G81 - > G85 are modal preparatory words used to perform drilling, tapping or boring. G81 -> G85 are used with the following address registers:

Q: Specifies peck depth.

P: Specifies dwell time.

R: Specifies retract plane.  

There are various names for cycles: subroutines, patterns, loops and macros. Cycles are very useful for machined features which are repeated, they only have to be programmed once so saving time, space and reducing the possibility of error.

Cycles fall into three main categories:

1. Fixed or Canned Cycles, supplied by the control writer or machine tool builder. They can not be changed by the machine user and are available to all programs. Drilling cycles are an example of these.

2. User Cycles, written by the user. They are available to all programs and are loaded and saved in the main program memory of the machine. A standard feature specific to your business may be programmed and made a User Cycle. An example may be if a keyhole shaped slot is machined in a lot of your parts it may be made a User Cycle.

3. Program Cycle or subroutine, written by the user. They are attached to a specific program and loaded or saved as a part of the file. An example would be a specific shape machined more than once in a particular product.

Some or all of the above may be available on your machine. Additionally the method of using them changes from machine to machine.