Nebia | The Premium Sustainable Shower
Nebia | The Premium Sustainable Shower
“You’ve taken thousands of showers. You’ve never experienced Nebia.”— Nebia
After raising more than $3 million on Kickstarter in less than a month in August 2015, Nebia was committed to an aggressive launch date for their premium water-saving shower system.
To get their product to market in a timely manner, Nebia and their San Francisco-based industrial design partner, Box Clever, determined that they needed a product engineering partner at the table who could provide a wide range of design engineering expertise: mechanism design, fluid seal design, design for reliability, Design for Manufacturing (DFM) and Design for Assembly (DFA). The partner would also need a deep appreciation for Box Clever’s premium fit and finish standards and a willingness to see the original ID vision through to production.
With an initial surface model and Color-Material-Finish (CMF) document already complete, PCH Lime Lab’s first work-stream was to quickly assess if the mechanical components driving the product volume could, in fact, fit within the confines of the surface model. This required several CAD “sprints” on critical features to determine the minimum mechanical envelope: the pressure regulator, the fluid switching mechanism in the neck and wand, the head articulation mechanism, and the flow path stack-up through the head assembly. In each case, the goal was to conceive of solutions that preserved the original ID intent, even if doing so was at odds with readily available off-the-self componentry or standard manufacturing and design guidelines for wall thicknesses and clearance gaps.
In parallel with this effort, a product requirements document (PRD) was needed to explicitly define the performance specifications of each product feature. This document ensures that all stakeholders (Nebia, Box Clever, PCH Lime Lab, and the CM) are on the same page with regards to performance points critical to the product’s value proposition and definitions of success for all engineering solutions. For this shower, critical specifications included the max operating pressure that the hydraulic system must withstand without leakage, the force to move the arm up or down from any position, the range of adjustment and the cycle life performance for the arm and head angle adjustments.
The PCH Lime Lab team not only had these capabilities but also had the flexibility that Nebia required to incorporate undefined product requirements and adjust to new requests. While Nebia had a core competency in fluid mechanics PCH Lime Lab had the expertise in design for manufacturing (DFM), surfacing, procurement, prototype building and testing, and program management.
With major product specifications understood, the engineering team explored a wide range of concepts for the key mechanisms and user touch-points. To test their merits, both low-fidelity mockups as well as high-resolution breadboards were made of the leading concepts, utilizing an internal team of skilled fabricators and CNC machining and 3D printing capabilities. These quick iterative loops were critical to the team’s ability to hone in on the best solution for each feature in the 6 weeks allotted for the Explore phase.
While prototyping and empirical testing can often illuminate a good design path forward, there are some challenges in product design that are most efficiently solved via analysis and simulation first. PCH Lime Lab used Finite Element Analysis (FEA) to understand and improve both the design of the fluid pathways and plumbing connections to ensure the glued plastic assembly could withstand the operating pressures defined in the PRD with a sufficient factor of safety. Several strength calculations were also performed to help determine the optimal geometry needed for the arm-bracket connection, the head assembly connection to the arm, and the mechanical stops on the arm slide and head articulation.
Throughout the design process, the San Francisco-based PCH Lime Lab team worked with both U.S. component suppliers and PCH Lime Lab’s Shenzhen-based manufacturing and tooling engineering teams to de-risk the manufacturability of the most complex assemblies and components. This early design feedback loop saved a significant amount of time in the overall schedule as it prevented hundreds of hours of detailed CAD work from being sunk into parts that may need reconsideration in order to be compatible with high volume production manufacturing processes.
Refining designs for prototype.
Creating sealed fluid paths in the shower-head assembly.
Early wand assembly prototype for pressure testing.
Routing hydraulic lines through the arm assembly.
The end of the design phase culminated in the fabrication of three fully featured, functional, production-intent prototypes. These units were assembled in house by mechanical technicians trained to evaluate ease of assembly and identify opportunities to improve the design for assembly consistency and cycle time. After demonstrating gross function of all product features, the units were subjected to accelerated life testing on custom-built fixtures to help understand the expected durability and reliability of the real production units under both normal and extreme use case conditions. Taking these units to the limits of failure gave the collective team a clear understanding of the performance boundaries relative to the expected use cases and helped guide a series of small design changes to improve the product quality.
“A better shower experience that saves you thousands of gallons of water a year.”— Nebia
While most product features performed well in these tests, the two tightly bent PVC tubes that route water through the head articulation mechanism were not meeting expectations. Although the required no leakage below 10,000 full articulation cycles, the units were rupturing at cycle counts below 5000. A new work-stream was kicked off to identify the optimum tubing material and geometry that could handle the fatigue stress – the result was a 1/4″ OD thin-walled THV fluoropolymer tubing. This high performance material had just the right balance of flexibility, burst pressure, and crack resistance for the application and had the added benefit of a super smooth surface finish that would minimize pressure losses from the regulator at the wall to the exit nozzles at the head.
TRANSFER TO MANUFACTURING
The final phase of PCH Lime Lab’s engagement was an intensive design for manufacturing review with Nebia’s contract manufacturing partner who was identified and recommended by PCH’s domestic manufacturing team. While DFM expertise is core to PCH’s service offering, finalizing DFM details with actual molders and tool-makers often deserves a phase of its own as each supplier has his own preference for tool shut-off design, gating and part ejection strategy. Spanning nearly three weeks, PCH Lime Lab engineers used a series of slide deck exchanges, video chats, and on-site visits to nail down the final details of each part with suppliers before cutting tool steel. During this time, newly hired engineers at Nebia started coming up to speed with the details of each part and began the slow process of inheriting the fully parametric CAD database (3D surfaces, solids, and 2D drawings) in its entirety. After all tools were kicked off, the Nebia engineering team managed pre-production modifications, and began shipping their very first product in January, 2017.
Parts and materials sourced in the U.S.
During the nine-month program, PCH Lime Lab successfully engineered the Nebia shower to meet its performance requirements while preserving Box Clever’s original industrial design objectives. The team remained agile during the development process and was able to react quickly to changing product feature requirements. In the process, the team designed and sourced over 100 unique components that when assembled, yield a shower experience that has never before existed on the market. The result is Nebia’s first product: a system that is both beautiful and innovative, saves 70% of water compared to a traditional shower, and is currently being manufactured in the United States at scale.