Hinkley Lighting, an innovative lighting manufacturer, wanted to develop a new light for its outdoor landscape category. Its design team wanted to break the design constraints of traditional luminaire housing materials for the LED light. Coated metals were the housing material of choice, but required designers to omit complex elements that would be too costly, not durable enough, or difficult for production.
Compared to metal fabrication, which requires time-consuming secondary operations, injection moulded plastic formulations can be produced as a net-shape moulded part in a single step, boosting productivity and lowering system costs. The materials also allow designers to integrate features into the part without the need for fasteners or post-production secondary operations.
Today’s consumers expect greater durability from outdoor luminaires, so the LED housings must have strong chemical and corrosion resistance, UV tolerance, high strength, high impact resistance and long-lasting aesthetics.
Metal, while high in mechanical strength, is still prone to corrosion failures as a result of weather exposure. Coatings such as zinc and paint, designed to delay corrosion, will wear eventually. This wear can occur more quickly in situations where metal is exposed frequently to elements, such as rain or salt water. Painted metals are also susceptible to chipping and scratching from daily use. This exposes bare metal, which reduces aesthetics and may eventually lead to luminaire housing failures.
Hinkley understood the potential for polymers to replace metal in this application, thus reducing cost, expanding design freedom, and closing the durability gap.
Metal replacement on the rise
Lighting manufacturers have historically shied away from polymers due to challenges of heat generated by non-LED lighting technologies. This particular application for the landscape light often referred to as “hardscape” lighting, poses unique challenges for polymers due to the light’s outdoor setting of temperature extremes and weather exposure. While metals have some proven performance in this environment, most polymers require numerous additives to achieve the UV stability, flame retardance, and long-term colour stability inherent to traditional materials.
Hinkley engaged PolyOne to understand the possibilities of creating their first polymer luminaire. Technical designers from both companies met to discuss design and performance requirements for the new product. In addition to robust durability requirements, the manufacturer was seeking multiple modern metallic finishes and sleek design.
PolyOne proposed recently launched Resilience™ LS polymer to address the requirements of the luminaire housing. The Resilience LS line of polymer formulations offers long-term colour hold, UV stability and thin-wall 5VA flame retardance to meet the technical requirements. Unlike other polymer compounds, rigid vinyl’s inherent flame retardancy and UV resistance require minimal amounts and reduced types of additives in order to maintain long-lasting colour and protection for the LED’s and electronic circuitry. So final parts have performance better than metal because the polymer is not susceptible to issues such as corrosion of such metal.
In order to achieve their design vision, Hinkley’s team leveraged PolyOne’s engineering and moulding expertise. Together they looked at options. They could mould parts from highly pigmented polymers but were concerned about unsightly weld lines, a possibility when two or more material flow fronts collide in the mould. The team needed a breakthrough approach that would deliver the bold, metallic colours and attractive designs that consumers desired, with the cost efficiency and modern design that Hinkley needed.
But what about the weld lines? If these lines showed up on the front of the luminaire, they would ruin the quality aesthetic the team was seeking.
Getting the mould right
Tooling design can be one of the most challenging aspects to polymer moulding. As industry leaders, PolyOne provided recommendations to minimise visible mould and gating lines in the final part. Close cooperation between the Hinkley and PolyOne design groups solved this issue by optimising the part’s geometry as well as the mould flow/gating system within the mould. Using computer design and simulation analysis, combined with years of experience in configuring vinyl tooling, the PolyOne team suggested changes to the mould geometry that strategically positioned location of the weld lines, if present, in an area not readily visible to consumers. The result was an exceptionally sleek product, apparently devoid of visible mould lines, which highlighted the modern design of the luminaire.
“Customers rely on PolyOne for the latest in material technology and technical expertise,” said James Mattey, marketing director, performance products & solutions at PolyOne. “We’re able to push the service envelope with in-house capabilities supporting the design, colour selection and processing guidance to drive successful commercialization of their products.”
Once in full production, the benefits of the vinyl material over metal was substantial:
- Fast Cycle Time: The high flow properties of the Resilience LS material allowed the moulder to reduce packing and cooling time while still producing warp-free parts.
- Increased Production: The new material allowed the moulder to increase part output, resulting in a machine cost-per-part savings.
- Reduced Scrap Rate: The new material’s properties and performance created parts with improved toughness and impact resistance.
- Total Manufacturing Cost Savings: Total costs were reduced by more than 25% compared to metal as a result of faster cycle times, increased productivity and reduced scrap.
Nuvi wins
The collaboration resulted in the award-winning Nuvi hardscape luminaire, which features a textured housing in multiple brilliant finishes. The durability of Resilience LS rigid vinyl complements the beautiful design to provide low maintenance performance and many years of lasting colour.
The development of Nuvi highlights the design potential of polymers in future lighting technology. The Resilience LS material provided Hinkley with cost savings and offered improved performance over the lifespan of the product. This is the first such product to switch from metal to polymer and prove the durability over alternate materials for the manufacturer. Due to its commercial success, a second, bigger iteration of the Nuvi hardscape light is underway.
© Chemical Today News
Read More: Nuvi landscape light relies on Polyone Resilience LS performance polymer
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