Additive Manufacturing

AUG 2017

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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AUGUST 2017 Additive Manufacturing CHECK THIS OUT 48 By Stephanie Hendrixson 3D Printing a Metal Shift Knob for Faster Cooling When challenged by Concept Laser to create a sample design that could only be produced through metal additive manufacturing, Nathan Huber, simula- tion services engineer at Phoenix Anal- ysis & Design Technologies (PADT), referenced his experience designing airflow solutions for refrigeration. He saw an opportunity to apply the same design thinking to a shift knob for his Subaru STI. By designing a hollow knob with a network of intersecting struts, Huber theorized that he could create a knob that would cool more quickly than typical knobs in a hot car parked in the Arizona sun. In addition to the goal of ther- mal control, the design also needed to be 1) possible to make only with additive manufacturing and 2) largely self-supporting (in other words, built with minimal use of sacrificial support structures) to minimize postpro- cessing time and effort. Huber also knew that the knob would be built on a Concept Laser Mlab machine stocked with Remanium Star CL, a cobalt-chrome alloy. Huber based the design on an existing 50.8-mm-diameter knob made of solid stainless steel, which weighs 1.1 pounds. Using ANSYS Spaceclaim Direct Modeler, he designed a knob with a web of triangular cells forming its outer skin. This geometry allowed the structure to be almost completely self-supporting during the build. The knob weighed 1.04 pounds following support removal and bead blasting. Huber then ran a thermal simulation to compare the AM knob and original solid knob. Using ANSYS Transient Thermal, Huber simulated both knobs with an initialized temperature of 150°F, a temperature that can be quickly reached in a parked car in Arizona, he says. After the simulations ran for 5 minutes, the final temperature of the solid spherical knob was about 115°F. Meanwhile, the 3D-printed knob had cooled to about 84°F, dissipating the heat faster and more efficiently thanks to the increased surface area of its web-like design. Metal 3D printing and design thinking enabled this shift knob, designed to cool rapidly inside a hot car. After five minutes, an ANSYS Transient Thermal simulation showed that the solid knob had dropped from 150°F to 115°F, while the 3D-printed knob cooled to 84°F.

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