The US Navy's new CMMs

One of my dear friends recently passed his basic training in the Royal Navy. Getting an inside perspective into the Royal Navy from him, albeit just for the basic training, has already proven to be very interesting. Steeped in tradition, yet constantly modernising, it’s a sector that seems to be ever evolving. Therefore, it shouldn’t come as a surprise that there is a story relevant to MQ as well as the navy. Granted, it’s about the US Navy, but the timing of it is nonetheless an interesting coincidence.

The Fleet Readiness Center East (FRCE) is one of the US Navy’s aviation repair and maintenance facilities. Its main responsibility is to repair and maintain airframes, engines and components, but also updates these systems. FRCE focuses on vertical lift aircraft and supports the US Navy and Marine Corps with engineering and logistics support.

Due to the nature of their focus, their tolerances in manufacturing, repair or maintenance is extremely tight. For this reason, they have long operated Coordinate Measuring Machines (CMM), but they have recently acquired two additional CMMs.

The new machine was acquired for the Precision Measurement Center (PMC), a component of the Advanced Measurement Services and Reverse Engineering Labs (AMSREL) division of the Maintenance, Repair and Overhaul (MRO) engineering department at FRCE. The importance of the new machines lies in their size as well as their accuracy. The new CMMs are able to measure large items down to an accuracy level of minute scale. An example given of the size of objects that may be scanned is the sponson fixture of the CH-53 helicopter, which is one of the US Navy’s largest helicopters. The sponson fixture itself needs to be accurately measured, which can be a challenge for other CMMs when it stands more than 2.1m tall and around 1m wide.

Stressing the importance of accuracy in aerospace technology, the FRCE gives us a useful analogy for the accuracy of the new CMMs: “To get a sense of this level of this accuracy, consider that the average human hair would need to be split into more than 30 slices to divide it into slivers ten-thousandth of an inch thick.”

Michael Wagoner, FRCE’s Metrology Engineering and PMC branch manager, commented on the effect that the new CMMs will have on productivity levels:

“The installation of two new CMMs increases the depot’s large-volume CMM capabilities by fifty percent; this translates into a significant reduction in turnaround time for the Naval Aviation Enterprise large support equipment and components. The new technology on these machines allows for both non-contact and contact measurements. We are very excited to grow our technology with these machines and deliver faster and more accurate measurements for our customers.”

The FRCE already had nine CMMs in use, but bringing their total up to eleven is a large advantage. Quite literally: it’s the size of the new CMMs that brings the most benefits for FRCE. Ben Pate, PMC operations manager, said that the FRCE has previously only had one large-sized CMM in use and the two new ones makes a range of operations more efficient: “Having access to multiple CMMs of this size gives us the capability to move more products at a faster pace, reduce downtime, better support equipment tooling, and eliminate that single point of failure when the machine is down for maintenance or yearly certification.”

Although the addition of the new equipment is a great boost in potential for the FRCE, the installation was not without its challenges. The size of the machines played a large part in this: the CMMs came with a massive granite table, each of which weighed nearly 14 imperial short tons. Delivery and installation of nearly thirty tons of equipment was only possible by excellent planning. The machines arrived on trailers, from where the lifting was outsourced to a local company that used a 40-ton forklift to manoeuvre them into the building. The whole process of planning up to installing the machines took just over seven months, with everyone involved making absolutely sure that all logistics and contractual processes were properly planned.

After a technician from the manufacturer of the machines fully finished the installation of the machines, they were put to use almost immediately. Additionally, there will be annual check-ups from the manufacturer to make sure that the CMMs are still operating to the ISO 10360 standard.

Among other processes, one of the main tasks that the new machines will be used for is first article inspection. This involves the FRCE measuring prototype parts created for them by defence contractors, so that they can be approved if they qualify according to the tight tolerances. From there, the contractors can be given permission to commence full production. Pate explained it as such:

“When the Defense Logistics Agency puts out a bid to purchase parts from different vendors, we use the CMM to do first article inspections on the parts to ensure they meet drawing requirements. The CMMs also support engineering investigations. We assist the engineers when they have a part and suspect something may be wrong with it. They’ll bring it down here for us to check against the drawings.”

The array of 11 CMMs now operated by the FRCE allows them to be incredibly flexible with their operations. Whether it’s oversized components that are brought to them to be measured on their large machines, or mobile CMMs that can be transported to measure components on site elsewhere, they have the capacity to do it. With their new acquisitions, they expect a significant rise in productivity, as their large-volume capabilities have increased by fifty percent.