Have been running machining centres for ten years and have seen issues with tool numbers. At my first place the work was divided up into small operations requiring on average 5 tools and at most 12-16 tools per op. It was our common practice to program from T1 onwards. We would clear the carousel between ops and we had drawers to keep tooling for each op. Each op had a standard setting sheet with a spreadsheet style tool list. Tools were always numbered in the order they appeared in the program. This is a great system when you are using smaller consumable tooling eg little drills and end mills.
I now work at a place with larger machining centres (60 pot ATC) and they mainly use modular tooling systems and indexable insert tools. With all the separate components it is not desirable to keep stripping down the carousel between jobs so people tend to keep favourite tools set in their machine and program with the tool number in mind. The things that annoy me about this approach are: -
1 Programs end up looking untidy and so do setting sheets.
2 When there is tooling shortage (which is most of the time) tools tend to disappear from your carousel anyway, then you have to remember their original position when you get them back.
3 You end up spending all day looking for something that is tucked away in someones machine not being used.
4 When you take a program with out of sequence tool numbers and run a machine with a migratory tool changer, things can get pretty confusing.
It will take a long time to resolve all the issues in our 'system' but in the meantime I have implemented a system on the machine I run that makes us more responsive in terms of setting tools/jobs. The control is a recent Fanuc. We setup a folder for an op/job. In there are main and sub pgms. We also write a 'parameters' pgm that lists the tools, work offsets and any other parameters required, eg
#101=1 (Spot Drill)
In our main program, rather than program tool numbers and corresponding offsets eg T1 M6;G43 H1 D1; we now put T#101 M6; G43 H#101 D#101;
This approach means that: -
1. The pgm is tidier, always starting from T#101 and continuing in sequence.
2. If a tool you can use (eg a spot drill) is already set up in the carousel at pot57 you merely change the value in the list (eg #101=57 Spot Drill).
3. No more swapping tools around, resetting tools, editing pgms (very risky with T, H and D to find), no loading up offsets or changing values in offset tables, even when running multiple ops - as each op has its own parameter list.
It works well and is saving us time and heartache. There are many other benefits you find out as you go.
We now do the same for Work Offsets as we never seem to get the same combination of setups twice...
Hope this hasn't confused the issue!