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Part Programming Commands
This chapter details the part programming codes used to run your Excellon machines automatically. The CNC-7, like all Excellon machines, has a set of part programming codes that can be used to control the machine for drilling, toolchanging, setting up machine parameters (such as feeds and speeds), and routing (if soequipped). Also, like other Excellon machines, the part program codes are backward compatible. This means that part programs from a CNC2,4,5 or 6 can be run on your CNC-7 without modification. Since newer controls contain new features, the reverse is not necessarily true (You may not be able to run all CNC-7 programs on a CNC-2,4,5 or 6). Part programs are simply data files, coming from any one ofa variety of sources or devices. This chapter will detail all available part program codes available for your use.
Part Program Headers
The M48 header is used to give your machine general information about the job. This includes the size of tools you want to drill and/or rout the PC board, the kind of measurement system you are using, the direction of the X and Y axis of the work, and otherdetails. These instructions may be generally listed in any order in the header. The part program header is optional. Most commands that you can program into the header can also be entered at the CNC-7 console before the program runs.
Part Program Body
The set of drilling and/or routing commands is called the part program body. It is usually much longer than the header and tells the machineexactly where each hole is to be drilled, which drill bit to use, what shape you want routed, etc. The commands are laid out in the sequence you want them carried out on the PC board. For example, one line of the program will tell the machine where to drill a hole, the next line will tell where to drill the next hole, the next line will tell the machine to stop and change the drill bit. Usually theprogram is carried out in sequence from top to bottom. However, some commands will tell the machine to move to another location on the PC board, go back to a previous line in the program, and repeat the pattern.
Excellon Program Format vs. Other Manufacturers
Because Excellon is a pioneer in the manufacture of computerized drilling and routing equipment, it was necessary for Excellon to developa set of commands to control the machines. The set is called Excellon Numeric Control and it uses the same commands for all Excellon machines. Some of these commands have become standard in the industry and are widely used by other manufacturers. The first machines introduced by Excellon were drilling machines. The set of commands used on drillers later became known as Format One. When Excellonintroduced machines with routing capability, a set of commands called Format Two was created. Then in 1979, Excellon revised Format Two to combine drilling and routing commands into one common set. The machines introduced prior to 1979 are called generation one machines and cannot use Format Two. They do not have all the capabilities of the newer machines. However, newer generation two machines canrun part programs with either Format One or Format Two commands.
What a Part Program Must Include
There is some information that the CNC-7 cannot know without being told. Some of the things that the part program must tell the machine are: Where to drill each hole Where to rout What size tool to use
Additionally, if the programmer wants to change the speed of the direction of a particulartool of the worktable, without file://C:\CNC%20Programming.htm 12/11/2003
Program Commands stopping the machine, the change must be made in the part program. Examples of these changes are: Reverse the direction of routing Change the table feed rate Change the spindle RPM
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Writing a Part Program
This section describes what you need to know to write a part program header and a...