The Challenge: Identify a partner who is able to aid in the development of an injection molded plastic spring
The Solution: Spectrum was able to deliver the resulting product to Lee Spring for market in eight weeks, from first concept discussions through to final production.

Mold base, ID core pin, and spring

Engineers at Lee Spring, an ISO 9001 Certified manufacturer of stock and custom mechanical wire springs, knew what they wanted, but weren’t quite sure how to get it. They knew they wanted the mechanical properties of Ultem, a plastic from SABIC Innovative Plastics, which offers outstanding elevated thermal resistance, high strength and stiffness, and broad chemical resistance. They contacted SABIC for recommendations of molders who were very familiar with the material, and Spectrum Plastics Group was at the top of that list. The engineers interviewed several molders, but ultimately made their decision due to the expertise they received from Spectrum’s technical team at Dynacept—a full-service rapid prototyping and quick-turn manufacturing division—ensuring Spectrum was the right partner.

Terry Gleason, sales executive for Spectrum Plastics Group, recalls Lee Spring presented the concept for an injection molded plastic spring to Brian Straiton, GM of the division, with the hope that the Dynacept team would be up for the challenge. “This wasn’t your typical open and shut,” Gleason commented, “the engineering team determined a minimum of six actions were needed to mold these, each needing to pull from a different angle.” The concept requirements include 270° of flat on the top and bottom, a specific number of coils, spring rates, and minimum cycles. Molding functional springs with specialty material that meet the requirements of Lee Spring was not an easy task, and presented many challenges.

Spectrum was open to that challenge, and in fact, this type of program was a good fit for Dynacept and its quick-turn manufacturing capabilities. “Quick-Turn Manufacturing, or QTM as we call it, goes well beyond rapid tooling and molding” explained Jason Bassi, business development manager for the QTM division. “To call what we do prototype tooling is not true, and an over-simplification, as it would leave out what our customers love about us—we provide production-quality plastic parts, delivered in prototype lead times. If your part is moldable, we can make it, period. We utilize high speed milling machines, wire EDM, and sinker EDM to mimic production tooling to provide production quality parts that often cannot be achieved through typical prototype tooling. We can deliver multi-shot, insert molded, or over molded parts, and even provide fully validatable tools for medical programs, tools that can be transferred to a cleanroom and run in an ISO 13485 environment at one of our two contract manufacturing facilities. In this case for Lee Spring, we were creating a number of very crisp parting lines, and shooting parts in a special engineering resin called Ultem PEI, with multiple actions. This wasn’t a prototype tooling project.”

Lee Spring evaluated many companies to support the development and manufacturing of their LeeP product line prior to selecting SPG. They ultimately chose Spectrum because SPG provided the solutions that other companies could not. “The Quick-Turn Manufacturing team, led by Brian Straiton provided the technical expertise and forward thinking to be successful on a program like this,” commented Eric Yee, global product manager for Lee Spring. “After speaking with Brian the first time, we knew the Dynacept Division of Spectrum Plastics Group could bring this concept to reality.”

In addition to tooling and molding, Lee Spring also benefited from the in-house SLA technology at Dynacept to further validate their concepts. A full menu of rapid prototyping capabilities is another benefit for Spectrum’s molding customers, as their programs can be quickly matched by in-house experts with the best RP process to prove out the part designs. Having world-class prototype capabilities within the same corporate structure not only makes it easy for customers to obtain parts made from multiple processes, even from multiple facilities simultaneously, but has added efficiency benefits of centralized order processing and project management.

Most companies are not structured to tackle a difficult project like this and succeed. The success of the LeeP spring program began with the upfront capabilities of the Dynacept facility in the CAD and tool design department, who provided the knowledge and experience to develop and implement complex tooling solutions. Dynacept’s lead mold designer stated: “This was one of the more challenging applications our team had been confronted with and before we committed to the project, we spent a few hours designing the part from the technical specifications provided and determined how to create the complex parting lines.” The engineering team at Dynacept has developed a process where Lee Spring can provide the specs of their desired spring design and the team at Dynacept can then design and mold the parts in a streamline fashion. This was then applied to a miniature spring design that required a modification to the existing process. The Dynacept team, combined with the technically proficient engineering team from their Connecticut production facility, gave Lee Spring the resources they needed to see their program go from concept to launch. And shared internal systems by the project management team allowed the spring programs to transfer from one Spectrum facility to the other in a very seamless transition, with prototyping available on site, on demand.

Colors are used to help distinguish the mechanical differences between the various options of the LeeP line of plastic springs.

Mr. Yee continued, “The complexity of developing prototype and bridge tooling and molding for our LeeP product line is not a trivial task. SPG combines a seamless approach to our concepts, they not only provide production quality prototypes, but also the ability to help launch our products and bring them into full production. This is a huge advantage when bringing to market a revolutionary new product. SPG takes on the difficult challenges and gives us the advantage we need to be competitive. They make it seem easy.”

In the past, most, if not all, high performance springs were manufactured out of metal. The advantages of the LeeP plastic composite spring line include stability of physical and mechanical properties up to 170°C, high strength-to-weight ratios, and excellent chemical compatibility and corrosion resistance. Additionally, they are non-magnetic and offer dielectric insulation and low flammability; they are also recyclable and RoHS/Reach compliant. It took years of engineering design and materials research for Lee Spring to release a line of plastic composite springs, but the end result is somewhat revolutionary in regard to how springs are perceived and used.

The springs are molded in six different colors with different formulations to provide different strengths. Many stock sizes are available by order directly from Lee Spring, with additional sizes always available by request for specific applications. Current applications include medical products, processing equipment, and delivery devices, food processing and packaging equipment, aerospace products, marine products, electronics and electrical equipment, water purification systems and chemical processing, and automotive interiors.

Total time to market was about eight weeks, beginning with the first concept discussions. CAD work and engineering took about three weeks, with periodic SLA prototypes delivered next day as new changes and innovations were brought into the fold. Complete tool design and build took approximately five weeks, from approved CAD to molded parts. While the shortest possible time to market time is often critical, in this case the importance was placed on quality and getting it right.

When presented with the challenge of creating the first molded LeeP spring, many competing companies walked away from this, while others were hesitant to commit on quality or delivery. Mr. Yee reflects, “Spectrum Plastics Group exceeded our expectations on just about every front…their ability to take our concept and develop extremely difficult prototype tools and then mold highly engineered plastics was unlike any company we have worked with. We continue to work with SPG on new development programs because we value their high level of technical expertise and excellent customer service. SPG is a vital partner in our LeeP product line.”

Tim Nakari is the director of marketing at Spectrum Plastics Group. He is responsible for new inquiries and aligning clients’ needs with Spectrum’s facilities and employees. Nakari can be reached at 303-453-3992 or