Hydrant Guard (R) is an innovative solution to a long-standing problem with one of the urban world's most familiar sights: the fire hydrant. By preventing water loss when an above-grade hydrant is sheered (or broken), Hydrant Guard can save thousands of gallons of water–not to mention lots of money for taxpayers.
In warm regions like Southern California, these kinds of sheers are frequent, but before Hydrant Guard no viable solution had been offered. Now, the fixture has already been implemented in over 65 hydrants and the numbers are growing rapidly.
By coordinating with Hydrant Guard's founder and design team, Eagle CNC provided a full-service manufacturing solution that turned a great idea into a great product.
First Contact
Hydrant Guard's founder and inventor had spent several years finishing prototypes and searching for a suitable manufacturing partner. Some had made redesign suggestions that undermined the feasibility of the product, while others failed to provide the capacity needed to package and distribute the product. Eagle CNC became involved through a distributor, and immediately got to work collaborating with Hydrant Guard's design team.
When Eagle CNC first received the design, it was a solid housing shaped like a modified spool. The body of the part was a dual flange with a groove around it that was designed to break on impact. Each item would be consumable. As with most of our new prospects, we took the design and got costing and recommended manufacturing methods.
Meanwhile, Hydrant Guard's founder reached out to end-users, or potential customers of the product, and discovered that they overwhelmingly preferred a reusable product to a consumable one. The design would have to be reevaluated.
Hydrant Guard sent a new design that involved two flange components held together by breakaway bolts. Instead of the product breaking in a controlled fashion, only the bolts would break. The only thing necessary to replace after a sheet would be those bolts.
Design for Manufacturability
One of Eagle CNC's main roles in product development is to incorporate Design for Manufacturability, or DFM, in order to maximize the quality to cost ratio. Eagle CNC's sales team used their previous knowledge and leveraged contacts in the industry to determine the best overall manufacturing methods.
Eagle CNC explored different methods of manufacturing. They looked at making components out of powdered metal, and they evaluated various casting methods. Volume is a big factor in determining the best manufacturing method, because setup costs are highly variable. Eventually, they decided on investment casting for the valve plates.
Value Engineering is also a big part of Eagle CNC's role. This role consists of Leveraging available processes to reduce costs. In some cases, like with powdered metal, it’s extremely precise and little machining would be used at all. There would be a lot of machining with investment casting or shell casting.
Eagle CNC also worked with a partner engineering firm to conduct an FEA analysis on the design. They sent the blueprints, production and material specifications to a group of engineers, who then simulated high amounts of water pressure that the product would be exposed to in the field. This FEA analysis led to further suggestions, pointing out potential weak points and ways to simplify the overall product.
A Regulatory Snag
As a cautionary measure, we recommend that all casting customers familiarize themselves with regulations regarding material and performance of products within their own industries. When designs were starting to look final and production was about to begin, Hydrant Guard's design team came across a surprising regulation that affected their product's legality.
In California, use of the high-grade steel suggested by Eagle CNC was not allowed for products interacting with municipal water supplies. Hydrants fell squarely into that category, and if they had continued with their planned material the product would not have met NSF standards. This discovery rendered the FEA analysis invalid, and they had to start again using only allowed materials.
Once again, Hydrant Guard provided a design and a concise list of desired functions. Eagle CNC made suggestions to improve Design for Manufacturability. Once both parties agreed that the design was ready, they created models and sent them to the same partner engineering firm to conduct another FEA. Once again, the firm conducted pressure simulations and provided Eagle CNC with color map overlays illustrating stresses in the design. Based on the FEA analysis, Eagle CNC suggested areas where the design could be improved, and they sent it to Hydrant Guard for approval.
Patented design
In early stages, Hydrant Guard's valve plates interlocked and were aligned by a pin that extended from the housing across the center. The FEA analysis revealed that much of the stress from water pressure fell onto that pin. Eagle CNC determined that if they cast a boss on the end of the plates, the FEA performance would be drastically improved. The pin would no longer need to bear the force.
In making this suggestion, Eagle CNC led Hydrant Guard to make a key change: they eliminated a component. Not only did this add strength to the finished product, but also improved its tolerance stackups. As with any product, fewer components mean fewer chances to deviate from desired tolerances.
Box: Tolerance Stackups
Imagine a stack of CNC-machined metal bricks. Each brick has to be precisely machined, but tolerances are measured based on the entire stack. If every brick is off by a small amount, that deviation is compounded in the stack. If you reduce the number of bricks in the stack, it's much easier to maintain that overall tolerance.
Most products aren't as simple as a stack of bricks, but the principal still holds: the fewer components go into a finished product, the easier it is to meet stringent tolerance requirements.
While Eagle CNC isn't responsible for making design decisions, a big part of Design for Manufacturability is to reduce tolerance stackups whenever possible. The design change sent to Hydrant Guard for approval was part of Eagle CNC's basic product development process, but it turned out to be an integral aspect of Hydrant Guard's patented design.
Full-Service Production
Hydrant Guard needed not just manufacturing, but also manufacturing resources. They didn’t have manufacturing resources in house, and they needed as clean a supply chain as possible. Hydrant Guard was able to supply engineering, design and sales, but they needed a partner to handle the rest of the business: manufacturing, sourcing, procurement and distribution. Before finding Eagle CNC, they were able to identify vendors that were capable of doing elements of the assembly, but they weren’t having any luck finding someone that could do the whole thing.
Eagle CNC is responsible for the following aspects of Hydrant Guard's production:
Machining
Castings arrive at Eagle CNC and must be machined to spec. Eagle CNC has machining fixtures designed and ready, and operators machine sub assemblies together to ensure fitup.
Serialization
Hydrant Guard requires full traceability because of their widespread distribution. Eagle CNC needs to serialize parts and show inspection documents and reports on every single part to prove that it meets the standard.
Assembly
Not only are Hydrant Guard valves machined and finished at Eagle CNC, they're also assembled into their final form.
Testing
Eagle CNC is responsible for pressure testing a set percentage of final products to ensure quality.
Distribution
Eagle CNC handles storage and distribution for Hydrant Guard. They distribute to different retailers because Hydrant Guard doesn't have a warehouse.
Eagle CNC also adjusted the stabilizer tabs. At one point it was a crosspiece running all the way across the valve to prevent them front rotating in the wrong direction. They found a way to integrate the stabilizer tab into another piece, not having it run all the way across.
Google dual plate check valves. They all have bosses on the underside that are not in line with the center of the plate. With HG it’s right in the middle.