energy vs. incandescent bulbs, their initial purchase price is high. Recent advancements in manufacturing have addressed this and other challenges, improving the performance and cost-effectiveness of LED light bulbs for the consumer market. Te latest model from 3M, St. Paul, Minn., is mercury-free, dimmable and designed to last 25 years (at three hours of use per day, or a total of 27,500 hours). Te 3M LED Advanced Light is a 13-watt (60-watt incandescent equivalent) omnidirectional light bulb that applies solid-state lighting technology to achieve long use. Te lamp produces 800 lm and is being sold in two versions: 3000K CCT soft white and 4000K cool-white. Tere are 9 LEDs for the cool-white version and 10 LEDS for the warm- white version. When 3M began the design and
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development of its 25-year LED light bulb, numerous aluminum components were included. For large production volumes, it was deter- mined the product was too costly to allow secondary machining. It would require net shape high-pressure alu- minum diecasting. Te global conglomerate selected
custom diecaster Pace Industries, Arden Hills, Minn., to join the design team that would develop the prototype and production diecast tooling for the LED light bulb.
A Close Partnership Pace Industries’ St. Paul division
had worked with 3M in the past as a supplier for aluminum diecast components used in 3M’s glue guns and other products. Its location near 3M allowed a close working
hile LED lights use minimal
relationship for its project engineers and die designers to assist in the prototype and development process. Some parts are painted for reflec-
tivity, and the dimensional tolerances on these parts are fairly typical for their size. One design challenge Pace’s chief diecasting engineer Eric Waa and his team conquered was heat sink wall thickness. Te walls were required to be 0.070 to 0.080 in. “Tat’s pretty thin,” he said. Waa described the 18-month pro-
cess from design to production on the LED light bulb. “A number of itera- tions of the tooling evolved during the diecasting development and design- for-manufacture process,” he said. “Because the components are small, thin-walled die castings, the tooling
presented some interesting challenges.” Te resulting design consists of four
different components cast in alumi- num alloy A380, including a heat sink core, the heat sink top and bottom, and a light ring. “The supplier/customer relation-
ship during this project has been smooth and effective. There have never been any issues related to the investment that was required for prototype tooling or the final pro- duction tooling,” Waa said. One key factor was the planning 3M did ahead of the development process. “Te tooling monies were planned for and made available for each phase of the development process, as we worked each time to maximize and achieve reduced manufacturing
Pace Industries developed this prototype mold for 3M’s LED light bulb. June 2013 MODERN CASTING | 37
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