Sherpa Design combines Carbon DLS printing and CNC machining for MBARI underwater vehicle component
Portland firm produces a complex polymer fluid manifold able to withstand 500 psi for use in autonomous ocean sampling
The Monterey Bay Aquarium Research Institute (MBARI) has made significant progress in refining the integration of a unique biological sampling system in an autonomous underwater vehicle (AUV).
MBARI required a fluid manifold for its Environmental Sample Processor (ESP) — a robotic laboratory that automates water sample collection and processing aboard a long-range autonomous underwater vehicle (LRAUV). The ESP handles up to 60 samples, and the manifold, a complex Toroid Ring with 60 dual ports, needed to be watertight, airtight, and capable of withstanding 500 psi without leaking.
A previous resin-based solution had failed in service due to excessive brittleness, inadequate performance at extreme temperatures, and poor compatibility with the institute’s cleaning agent — water with 10% bleach.
MBARI evaluated metal 3D printing as an alternative but found the cost prohibitive, so Jim Birch, Director of MBARI’s SURF Center, then identified Sherpa Design through Carbon’s certified production partner network and engaged the Portland, Oregon firm to manage both design and fabrication.
Material selection and process development
Sherpa selected Carbon’s EPX 150 resin for the application, citing its machinability, resistance to machining coolant, and compatibility with the 10% bleach cleaning agent. The material also offered a lower coefficient of thermal expansion than the previously used resin.
Because the part’s 60 internal fluid passages and difficult-to-access threads exceeded the surface finish and tolerance capabilities of 3D printing alone, Sherpa combined Carbon Digital Light Synthesis (DLS) printing with 5-axis CNC machining in a hybrid workflow. The team conducted iterative test printing, measurement, and scaling compensation to bring printed features within tolerance before programming a series of drilling, reaming, and T-slot cutting operations to maintain fluid port concentricity.
The manufacturing split shifted from an initial estimate of approximately 95% additive to 75%, with CNC finishing accounting for the remainder.
“Achieving such solutions efficiently required close collaboration between our additive specialists and our CNC machinist — a unique advantage of working with Sherpa as a Carbon Partner,” said Pat Barrett, Owner of Sherpa.
The finished component passed static pressure testing to 500 psi at MBARI. It was subsequently installed in the ESP and entered field trials aboard the LRAUV.
“MBARI’s scientific instruments are transforming our ability to monitor the health of aquatic ecosystems. The team at Sherpa helped create a custom component that will ensure our technology can gather much-needed environmental data even in challenging ocean conditions,” said James M. Birch, Ph.D., Director of the SURF Center at the Monterey Bay Aquarium Research Institute.
