Codes and Formats
Name two things you must understand from a programmer's viewpoint, about the configuration of the CNC machining center you are programming.
Any two of the following are acceptable answers.
- machine components
- directions of motion (axes)
- programmable functions
What is the most important reason why you should prepare to write CNC programs?
The most important reason for preparing to write a program is that you do not have to break your train of thought while programming to come up with the information you need to write the program.
What G code is used to specify clockwise circular interpolation?
G02
What G code is used to specify counter-clockwise circular interpolation?
G03
Provide the reason why the various types of compensation are required on a CNC machining center.
All compensation types allow you to ignore certain tooling related issues as you create CNC programs.
Provide the reason why you must understand the three basic motion types on a CNC machining center.
Without an understanding of motion types you cannot write commands that cause cutting tools to machine workpieces.
Name two reasons why programs must be structured in a strict manner on a CNC machining center.
Any two of the following are acceptable answers.
- to help familiarize you with programming
- to provide consistency among the programs you write
- to allow cutting tools to be re-run on their own
The easiest way to specify the arc size in a circular interpolation command is with:
an R word
Which G code is used to specify the XY plane?
G17
What G code is used to specify rapid motion?
G00
List four key concepts that you must understand to become proficient with a CNC machine tool as a programmer.
Any 4 of the following are acceptable answers.
- know your machine from a programmer's viewpoint
- prepare to create CNC programs
- know how to program the three basic motion types
- understand the compensation types
- provide structure to your programs
- understand features that simplify programming
List three key concepts that you must understand to become proficient with a CNC machine tool as a set-up person/operator.
Any 3 of the following are acceptable answers.
- know your machine from an operator's viewpoint
- the three basic modes of operation
- key operation procedures
- verify programs safely
Which G code is used to specify the YZ plane?
G19
What is the formula used to calculate per minute feedrate?
RPM x IPR
Which programming feature gives the CNC machine operator a choice between one of two conditions?
block delete
Which switch/selector is the most important on a CNC machine?
Mode switch
Which programming feature allows you to specify coordinates, like those on a bolt circle, relative to a central position with angle and radius?
Polar coordinates
When machining the outside profile of a workpiece, what is the extra motion called that moves the tool away from the last milled surface.
escape distance
What is the point of reference with absolute positioning?
the program zero point
What G code is used to specify linear interpolation?
G01
You can divide almost all movements that cutting tools making during the execution of a CNC machining center program into one of three types. List these three motion types.
- rapid motion
- linear interpolation
- circular interpolation
List four of the steps to follow as you prepare to create CNC programs.
Any 4 of the following are acceptable answers.
- prepare the machining process
- select the cutting tools
- calculate cutting conditions
- plan the workholding set-up
- calculate co-ordinates needed for programming
- create set-up and production run documentation
What is the point of reference with incremental positioning?
the cutting tool's current position
If you are programming a 1/2 inch diameter milling cutter's centreline path to cut a 1 inch fillet radius, what is the R word value?
0.750"
Name the four kinds of CNC program format.
- program start-up format
- tool ending format
- tool start-up format
- program ending format