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End-Use Case Study
Shuttleworth Inc. supplies material handling conveyors to customers throughout the world and to industries as varied as their locations. Whether glass, food, pharmaceuticals, metals, or electronics are moved through a manufacturing process, they each create a unique set of demands on the rollers that convey them along their path.
While Shuttleworth is renowned for customizing its products to end-user applications, Klaus Daenzer, Senior Plastics R&D Engineer, felt a single material for rollers capable of performing in any of their most demanding projects would allow them to lower costs and provide faster responses to customers. When calculating the most exacting of the needs for their new EP-0047 roller, Daenzer found many of the requirements were shared.
Structurally, the material had to maintain a high strength to weight ratio to achieve the goal of maintaining roller pressure at less than 4% of the carried load. Since many customers’ processes involved annealing, extreme temperature resistance was mandatory. Continuous rotation dictated that lubricity and wear resistance be central properties and, for the needs of the electronics industry, the roller material itself had to be both electrically conductive and free of silicone oil. This variety of parameters dictated a custom material and his experience with RTP Company product development engineers led Daenzer to enlist their services.
In response, RTP Company formulated an RTP 1300 Series conductive and lubricated polyphenylene sulfide (PPS) compound. With a tensile strength of 9000 psi (62 MPa) and specific gravity of 1.54, the new material yields a sufficiently strong, yet lightweight part.
As it is so much lighter than conventional steel rollers, Shuttleworth’s EP-0047 rollers can make use of a very low drive pressure, greatly reducing wear and still gently conveying parts.
The inherent properties of PPS offer a continuous use temperature of 400 degrees F (204 degrees C) and excellent chemical resistance. The rollers easily passed Shuttleworth’s 6-month long heat durability test. To make the material ideally suited for ESD (electro-static discharge) sensitive uses, RTP Company engineers added a conductivity package resulting in a volume resistivity of 103 ohm-cm maximum and surface resistivity of 105 ohm/sq maximum. These properties allow the rollers to harmlessly bleed dangerous static charges away from any sensitive electronic parts they may convey.
Using a silicone additive is the traditional approach to decrease friction between surfaces in contact with one another. At times, a high loading of silicone will cause particles to migrate to the part’s surface, creating a source of potential contamination. Because of its harmful effects on soldered connections, the electronics industry prohibits its use. To meet this challenge, RTP Company and Shuttleworth tailored a combination of PTFE and Fluoroguard® synthetic oil into the PPS compound, providing lubricity superior to that of silicone.
According to Daenzer, “RTP Company’s addition of Fluoroguard® allowed us to achieve both the necessary lubricity and eliminate the plate out common with higher loadings of PTFE.” He also credited RTP Company’s processing assistance provided by its Technical Service staff with further enhancements to the rollers surface appearance and smoothness. Daenzer cites RTP Company’s, “Turnaround, service and execution of an innovative solution is very impressive!”
In business for over 40 years Shuttleworth Inc., of Huntington, IN, supplies conveyor systems used in a wide variety of applications in numerous industries, for more information visit their website at www.shuttleworth.com.