The advent of private space vehicle development companies has transformed the manufacturing environment for rocket and satellite components. Previously, government organizations, including NASA and the U.S. Department of Defense, sponsored the majority of space-related manufacturing. Now, moneyed entrepreneurs behind Blue Origin, SpaceX and Virgin Galactic are driving the next generation of space technology progress.
The growing private space business constitutes a new industry with new relationships, new requirements and new opportunities for manufacturers.
Gray Manufacturing Technologies is one vendor benefiting. The Denver, N.C.-based shop has taken advantage of those opportunities with its application of advanced machining and, most importantly, automation technology to meet the increasing demands of the spaceflight industry.
Gray’s product mix is high and individual part volumes are low. “The vast majority of our business is either aerospace [aircraft] or space and satellite components,” said Gary Holcomb, president and CEO of Compass Precision, Gray’s parent company. “Most jobs are five to 10 pieces, and most are different from prior jobs. They are not exactly prototypes but are complicated parts in very small volumes, and we ship upwards of 100 jobs per month.”
Because the space vehicle companies constantly modify and improve their technologies, engineering changes are frequent. “We may make five parts for a customer, then they may order five more parts, but with different dimensions,” Holcomb explained. “There are frequent change notices and a lot of moving in and out of production schedules. We might get six orders due three months from now, but a week later they need two of the orders sooner while two others get moved out of the production schedule.”
Automation has proven to be a key component of Gray’s approach to space and satellite products machining services. “When we first talked about automation, we were looking at it from a capacity issue,” said Gray Manufacturing Operations Manager Evan Grose. “We didn’t have the room to keep loading the same part over and over again on the same pallet.”
To increase its spindle uptime and production flexibility, the shop acquired two five-axis MILL E 700 U machining centers from GF Machining Solutions LLC, Lincolnshire, Ill., situated in a cell that includes a System 3R Transformer modular robot along with a 12-pallet loading station. The robot rides on a rail to switch pallets in and out of the machines, as well as to load and unload pallets offline at the loading station. These combined capabilities provide for extended lights-out operations at Gray.
GF Machining Solutions automation enables Gray to efficiently handle its low-volume/high-mix workload. “The flexibility of the equipment is very important,” Holcomb said. “During the day we focus our resources on making the one-, two- or five-piece jobs for space customers. Then, before we go home, we take the non-space work—basically higher-volume aerospace jobs that are already programmed—and run it at night. We utilize what the MILL E 700s offer in terms of programmability for the complicated, very small lots during the day, then use the automation capabilities for the somewhat higher volume, non-space work that we run lights out.”
Unlike typical multi-pallet systems that may limit the amount of untended production to whatever is loaded on the pallets before the lights are turned off, the Transformer robotic system removes pallets with completed work from the machine and replaces them with loaded pallets. It then unloads and reloads parts on the idle pallets while machining continues uninterrupted. “We refer to it as automation for the automation,” Holcomb said.
For unattended operation, tool breakage detection is set in the machining program. If a tool breaks, the machine stops and changes the tool. The MILL E 700 U machines have more than enough tool storage to support Gray’s extended untended operation, with tool wear compensation and substitution of redundant tooling called out in the program as necessary.
“We proceeded down the path of automation because of the increasing complexity of our work and because it’s harder to find employees with the right technical skill sets,” explained Holcomb. “We chose the robust Transformer robot instead of an articulated robot because the machining center’s ability to make complex movements makes the use of a fully articulated robot unnecessary,” he added.
The alternative to the robotic automation system would be more machines, Holcomb said, “and depending on how many machines are in use, more people too, because we can’t expect an operator to run seven or eight machines. Based on our current order levels and without the robotics, we would need at least three more machines for a total of five and two more people. And at this point in our business, it’s more difficult to find the people than acquire the machines.”
While part volumes presently are low, higher volumes are anticipated that will enable the shop to fully exploit the capabilities of the Mikron MILL five-axis machines and robotic pallet system. “Higher volumes in this case doesn’t mean millions of pieces,” Holcomb said, “We need a few dozen pieces as opposed to five to 10.”
Automation will become more important as the commercial space vehicle business grows and matures. According to Holcomb, the shop is experiencing a migration to higher volumes of parts that it has already programmed. This means less demand for programming and more demand for extended machine time that the GF Machining Solutions automated cell provides.
Holcomb went on to say that machining speed, in addition to automation, is critical to successful aerospace and space vehicle component production—most of which requires processing of complicated aluminum parts at high rpms.
In addition to the two machines in the automated cell, Gray has a Mikron MILL E 500 U and a MILL S 600 that feature seven-pallet carousels. One machine has a 36,000-rpm spindle, the other a 20,000 rpm.
Contributing to the shop’s responsiveness and efficiency, Gray is committed to a “single-setup” approach to machining, according to Jerry Soots, former Gray Manufacturing general manager and president and now consultant. To achieve this production goal on a five-axis milling machine, Soots explained, Gray leaves strategically placed 0.005"- to 0.010"-thick tabs on raw workpieces and grips the work in a dovetail fixture that permits machining of all part features.
The fixturing provides plenty of distance between the bottom of the part and the machine. Because of this, the shop can reach features underneath and machine at every angle. Once the part is finished, it is measured on a CMM; when it’s compliant, they machine off the tabs.
The burgeoning private space manufacturing industry is creating new relationships between spacecraft companies and their suppliers. Thirty years ago, vendors had to pitch their capabilities to the aerospace companies, who generally weren’t actively looking for suppliers. Unless a component was part of a new aircraft program, part design changes were rare.
“Today, the commercial space companies are doing everything on the fly,” Holcomb said, “It’s a completely different mindset. They are aggressively looking for qualified suppliers who can be responsive to their constant stream of new products and ongoing design changes.
“The latest ISO certifications and AS 9100D are the minimum qualifications. You’ve got to be very technically competent. You’ve got to be able to make these demanding parts in relatively low volume, sometimes in aluminum, sometimes in more difficult materials. You’ve got to be agile enough to accommodate the fluidity they require in production scheduling. Our five-axis mills and automation from GF Machining Solutions play a key role in achieving all these demands.”
For information on Gray Manufacturing Technologies, visit gray-mfg.com or call 704-489-2206. For information on GF Machining Solutions, visit www.gfms.com or call 800-282-1336.
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