American manufacturers are starting to talk more like Europeans, where fuel is costly, and words like “sustainability” pepper conversations.
One case in point is the 2020 Sustainability Report for freight and transit rail manufacturer Wabtec Corp., Wilmerding, Pa. The report describes the Metroflexx smart brake for mass transit rail, which was “designed with sustainability in mind—95 percent of the system’s parts can be recycled at end of life.” Using additive manufacturing (AM) also combined 30 parts into one.
Another highlight in the report is the FLXdrive, Wabtec’s new battery-electric rail locomotive, powered by a 2.4-mW system. In October the locomotive was in trial use by BNSF Railway in California.
More important is Wabtec’s use of AM: 3D-printed parts are in the smart brake and the battery-electric locomotive, among many more components the company is producing. Wabtec claims to reduce manufacturing waste by up to 80 percent using AM.
“Although the energy consumption during the process is sometimes higher than conventional manufacturing methods, the material utilization leads to overall reduced resource usage,” said Jennifer Coyne, additive manufacturing leader. “Some other considerations that make AM more sustainable include less waste due to material optimization and reuse, eliminating specialized tooling and fixtures; and design freedom to produce more durable parts that require fewer replacements over their lifecycle.”
Wabtec has designed 42 different parts for AM production and made 18,000 of them to date. Such parts include seals, cable cleats, heat exchangers, pneumatic brake panels, HVAC parts and tools and fixtures. The company’s goal is to produce more than 25,000 AM parts a year by 2025.
One of the metal printing technologies under development is binder jetting, said Coyne. It needs maturing “but I think it has the right characteristics to make it the most cost-effective, medium-volume (100-1,000) AM for relatively simple and small parts (less than 200-300 mm).”
Coyne offered some considerations. Lattice structures are not possible; it’s not suitable for large parts because the builds have to be handled in their green state when they’re most fragile, and it is not good at making thick and thin features adjacent. Parts may need support in the sintering furnace, but the operator can also nest the green state components because they don’t have to be welded to the build plate. “Sintering, in our experience, is like the black magic in binder jetting,” Coyne joked.
Sintering considerations include 60-70 percent volumetric shrinkage; shrinkage combined with friction from the build plate can cause failure; and, because the material is almost the consistency of putty in the furnace, gravity’s effects can take over.
Wabtec uses the H2 binder jet printer from Coyne’s previous employer, GE. She cautions anyone shopping for a binder jetting solution to consider the economics of the entire process—not just the printer, but the necessary curing oven and sintering furnace too.