End users are realizing the benefits of having both additive and subtractive functionality in a single, self-contained system. As one of the few manufacturers that introduced a hybrid machine last September at IMTS 2016, we are among those creating this fresh path with tweaks and trends surrounding this combined technology, and the advancements continue to unfold quickly. One of the areas leading the way at this moment surrounds real-time, adaptive CAM software that is spurred by the current workpiece condition, gleaned from metrology device data.
To explain this in more practical, relatable terms, let’s consider an actual manufacturing scenario: We all know that in the aerospace jet engine turbine industry there are high-value components within the engine. Many are structural parts using very expensive, complex-featured castings and/or forgings. A new trend with our customers in that sector is using the hybrid approach and creating a much simpler casting strategy. The complex features are added—in our case via laser deposition—and then finish-machined conventionally (subtractive). You can readily recognize just a couple of the benefits so far: lower raw material costs and greater material yield for the material supplier, greater cutting tool life and less need for high-priced, highly engineered cutting tools for machining.
The first operation conducted on the simplified casting/forging is scanning the current geometric condition of the workpiece. A variety of metrology devices could be used for this that can be integrated into the machine, or if it’s scanned on a station just outside of the machine’s work envelope, a structured-light scanning system or laser-scanning system might be used. The point cloud data from that scan is collected offline on a shop-hardened and extra-powerful PC stationed near the machine. That data is compared to the CAD model of the workpiece, functioning almost as a “master” gage, and any geometric variances are noted and passed on to the CAM software. The CAM software makes an adaptive shift of the toolpath to ideally position the additive structure elements on the workpiece based upon the present part condition. The CAM software adapts its program to ensure that the variances are taken into account when adding and subtracting material.
Sounds so simple, doesn’t it? Obviously there is heavy-duty data manipulation going on that is mind-bending for those of us who lean more towards mechanics and kinematics than bits and bytes, but it is incredibly fascinating to me. So, in our scenario the material is deposited and then a subsequent, programmable scan occurs in the machine, likely with a scanning probe or laser light striping probe, to determine the current condition of the workpiece and its geometry. Once again the instrument data and the CAM software do their magic, and any variance information is fed back to the machine control and the subtractive machining operations ensue. This is an elementary explanation and example, but you get the idea of what’s happening and, with just a tiny spark of the imagination, where it can lead. Right now we are experimenting with a heat-treat routine in our laser head as well as an eddy or Foucault head in our system. And of course, all of the data collection aspects can connect into plant-wide systems.
This is an exciting time of discovery in our world of manufacturing technology. While the head-spinning is fun, we must remember that no matter what manufacturing method or functionality is used, the end game is to achieve the desired outcome on the workpiece. In other words—deliver the optimal results that our manufacturing customers need for that particular project, which are accurate parts made in the most efficient, economical way possible. Let’s not get so caught up in the next cool thing that we lose sight of the practicality and application of the next breakthrough. It might be cool but cooler heads prevail. What’s prevailing now in the hybrid-machining sector is the combination of metrology hardware and adaptive CAM software and its applications are very practical indeed.