One of my cardinal rules is that all sizing adjustments should be done with offsets. However, I do – from time to time – see operators making sizing adjustments by changing programs.
I’m normally speaking from an efficiency standpoint; sizing adjustments with offsets can be done while the machine is in cycle. Modifying a program requires the machine to be stopped. But there can be a safety issue here too. Modifying programs requires more skill – and if mistakes are made – the results could be disastrous.
While mistakes can be made when modifying offsets, the danger is not nearly as great. Operators change offsets for the purpose of sizing on a very regular basis – and they get good at it. Applications for which operators elect to modify programs are pretty scarce. Possibly tool pressure is causing a turned diameter to be a given diameter at one end and another diameter at the other (taper is being induced). This is an application that can be easily handled with offsets that some operators elect to handle with program modifications. And again, since it isn’t something they do on a regular basis, some of your operators may not be very good at it.