Re: Quality assurance for CNC programs - Help needed.
- From: Eric Stevens <eric.stevens@xxxxxxxxx>
- Date: Tue, 09 May 2006 22:10:35 +1200
On Tue, 09 May 2006 08:38:32 GMT, Anthony <tonytn36sp@xxxxxxxxxxx>
wrote:
Eric Stevens <eric.stevens@xxxxxxxxx> wrote in
news:2d5062lae6etbgp21eabr0v32fvt6pv8do@xxxxxxx:
I would be grateful if somebody could point me to relevant Standards
or Code of Practice documents, or the like, if any actually exist.
I doubt you will find anything specific to CNC, however, CNC macro
programming is basically the same as any other programming. It really
doesn't matter what type of programming you are doing, the same basic
rules and methodology still apply, the only real difference, in the grand
scheme of things, is the syntax, command names and definitions. And one
rule is to always check operator/user input for out of range variables.
Sadly, this rule is rarely followed in CNC programming because of the
extra time it takes to program, and depending on the macro's purpose. In
a job shop where you may have a macro for boring, but may be working on a
1" bore one day and a 30" bore the next, it would be hard to define out
of range variables. However, in a production environment where the
variable extremes are well defined, it only makes sense to check for out
of range variables in the macro.
Sanitiy checks are worth the time.
I know what you mean but this is beyond that.
The major demand for the machine is a range of cast bodies which can
be anything from C.I. to 316. They come in 4 sizes. Each size has a
range of simple variations which mean there is about 28 of each. Much
of the machining is hand coded (about 7000 lines in all) but some is
so complex that it has been machine coded. I don't know how many lines
but more than 30,000. What the machine actually does and how it does
it is determined by feeding the program a long list of parameters
which guide its weaving through the maze of options.
Somewhere along the line someone pressed the RESET key at the exactly
the wrong moment. On all but that machine that would not have mattered
but on that one machine it cleared a number of # variables which would
not have been touched on the other machines in the same circumstances.
This only mattered on the one 20 line program.
Until after the accident nobody knew that the machines were configured
slightly differently and would behave differently. In another
programming environment this might have been discovered, recorded and
perhaps the machine would have been reconfigured. But it seems to me
that the general CNC environment seems oblivious to the need to guard
against this kind of problem which is why I am asking if anyone knows
of any procedures for properly documenting the programming
environment.
I can't go into more details but it killed an entirely innocent man.
This is not a joke which is why I am asking for help.
Eric Stevens
.
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