Using a CMM as machine probe

Hey guys,

So I stole this idea, but the fellas that use it say it’s a common industry practice.

Does anyone use a CMM to get the offsets for a given part to use in a mill? This would replace in-machine probing with a macro to change work coordinate offsets using CMM data.

This wouldn’t work without a lot of assumptions. First, you’d have to have a pallet system that goes from the CMM to the mill. Said pallet would need to repeat within very tight tolerances. The pallet-receivers would likewise need to be indicated perfectly straight in the mill and CMM, and every fixture would need a universal location for a tooling ball. Last, you’d have to track measurement for a given part or fixture, especially if you were using multiple mills.

I can hear the opposition now. Hear me out. I know it doesn’t have the same functionality as a machine probe, but if your pallet system is universal for all your jobs and never moves, fixture probing would only speed up certifying that the base plate hasn’t moved. There are several advantages to the concept, but it’s less of an alternative to probing as much as it is a specialized process for specific parts, say with multiple datums.

I don't know about it being common industry practice as I only know 2 companies going this route including my employer. But the process is expensive to setup so the gain's have to be big enough for upper management to see. I would think only large production shops would have the money and the reason to automate this way.

You could get around a sloppy pallet system or if your machine's pallet system isn't connected to a CMM just have 3 tooling balls on the fixture so you can have a 3+2+1 alignment based of the tooling balls. Obviously your machine would still need to probe but it would reduce cycle time.

Using this process only for setting up work coordinate systems is not the end goal either.