Our Machining Center Stiffness Tester was built after we took delivery of a new vertical machining center and found that we could not run the same programs and tooling as the old machine. It seemed like the new machine was not as rigid as the old machine. After trying to find out how to test the stiffness, we came to the conclusion there is no commercially available tool to do this. A ball bar tests the positioning of the machine under no cutting load. We needed to measure what happens when there is cutting tool pressure pushing the tool away from the work piece.
The unit shown in the picture has an air cylinder to apply pressure between the table bracket and the arbor mounted in the spindle. A load cell tells you the pressure, this is similar to the force generated by an end mill cutting material. The dial indicator measures the deflection between the tool and the table.
We tested several small VMC’s and found our unit to be limper than any others. Had we had this tool available prior to taking delivery of the machine we could have saved $36,000.00.
If you would like to know more,
please call Ed Danzer at 360-264-2141