Delcam will highlight the ways in which machining and inspection can be integrated more closely on the ADS pavilion at the Paris Air Show to be held at Le Bourget from 20th to 26th June. These new processes, which can be grouped under the heading of "adaptive machining”, include techniques like electronic fixturing and On-Machine Verification.
The traditional relationship between machining and inspection is that machining is completed first and the component is then transferred to a dedicated piece of inspection equipment to be approved or rejected. However, as machining techniques become more sophisticated, and as components become larger and more complex, there are a growing number of cases where closer integration is required to give higher productivity and reduced wastage. Instead of a simple linear progression from CAD to CAM to machining to inspection, a more complicated series of steps is needed, with extra data needed to fill any gaps in the information available at the various stages.
The programming of most machining operations is based around knowing three things: the position of the workpiece on the machine, the starting shape of the material to be machined, and the final shape that needs to be achieved at the end of the operation. Adaptive machining techniques allow successful machining when at least one of those elements is unknown, by using in-process measurement to close the information gaps in the process chain.
Delcam is in a strong position to advise companies wishing to implement these new techniques. The company has a unique combination of expertise in software for both machining and inspection, which has been built up over many years of development of PowerMILL, the world’s leading specialist CAM system, and PowerINSPECT, the world’s leading hardware-independent inspection software.
The most common cases when adaptive machining techniques are needed are those where the exact position of the workpiece on the machine is unknown. With larger components, such as aerospace structures and tooling, achieving the correct position and orientation of the stock on the machine is a major challenge, taking many hours of checking and adjustment. It is often easier to adjust the datum for the toolpaths to match the position of the workpiece, than it is to align the stock in exactly the desired position.
On-Machine Verification also uses probing equipment on the machine tool. It allows initial checking of machined parts to be carried out in situ on the machine rather than having to transfer them to coordinate measuring machines for inspection. The main advantage is that any mistakes are discovered where they can be corrected – on the machine tool. Repeated cycles of machining and inspection, interspersed with long set-up times on the respective pieces of equipment, are avoided, meaning that overall manufacturing times can be reduced.
The most obvious benefit of On-Machine Verification is for those companies that do not have existing inspection capabilities or for cases when the component is too large for their equipment. However, On-Machine Verification can also give huge time savings by enabling the quality of the component being machined to be monitored at all stages in the manufacturing process. This allows any errors to be detected earlier, and so corrected more quickly and at lower cost.