Strategies for a scalable multi-robot large scale wire arc additive manufacturing system
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36 MATERIALS SCIENCE↗
Engineering topics
Noakes, Mark W.
Publications and source records attributed to Noakes, Mark W..
Large Scale Metal Additive Manufacturing for Stamping Dies
Oak Ridge National Laboratory (ORNL) worked with Dienamic Tooling Systems (DTS) in a follow-on Phase 2 effort to develop and demonstrate additively manufactured conformal cooling for hot stamping dies, providing a new industry capability that did not previously exist. Current approaches to die cooling are nonoptimal and based on what can be machined with traditional technologies. The printed approach to hot stamping cooling channels allows an analytical needs-based size and placement approach to cooling. Cooling is optimized and parts count is reduced producing a simpler more reliable faster to manufacture stamping tool. An additively manufactured hot stamping die with conformal cooling channels was manufactured and successfully tested in a real-world environment.
36 MATERIALS SCIENCE↗
Altering the Supply of Shielding Gases to Fabricate Distinct Geometry in GMA Additive Manufacturing
Wire arc additive manufacturing (WAAM) is the process by which large, metallic structures are built, layer-by-layer, using a welding arc to melt wire feedstock. In this process, the proper selection of the shielding gas plays a vital role in the achievement of structurally acceptable part geometries and quality surface finishes. In this study, the authors used either a ternary mix (He, Ar and CO 2 ) or a binary mix (Ar and CO 2 ) of shielding gases to deposit wall geometries using an open loop-controlled WAAM system developed at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility. The binary blend produced a wider and shorter geometry, while the ternary blend resulted in a narrower build that was more equivalent to the CAD geometry. The data indicated that the binary blend provided a higher oxygen concentration in the weld as compared to that of the ternary blend. The results imply that the arc characteristics and heat input had a significantly higher impact on the weld penetration than the surface tension effect of surface active elements. This was further verified by developing and applying a high-fidelity computational fluid dynamics (CFD) model of the thermophysical properties of gas mixtures. The results from the model showed that, while the influence of increased oxygen concentration on the surface tension for the binary blend led to a deeper penetration, the ternary blend gave rise to heat flux to the workpiece.
36 MATERIALS SCIENCE↗
Investigating the Linear Thermal Expansion of Additively Manufactured Multi-Material Joining between Invar and Steel
This work investigated the linear thermal expansion properties of a multi-material specimen fabricated with Invar M93 and A36 steel. A sequence of tests was performed to investigate the viability of additively manufactured Invar M93 for lowering the coefficient of thermal expansion (CTE) in multi-material part tooling. Invar beads were additively manufactured on a steel base plate using a fiber laser system, and samples were taken from the steel, Invar, and the interface between the two materials. The CTE of the samples was measured between 40 °C and 150 °C using a thermomechanical analyzer, and the elemental composition was studied with energy dispersive X-ray spectroscopy. The CTE of samples taken from the steel and the interface remained comparable to that of A36 steel; however, deviations between the thermal expansion values were prevalent due to element diffusion in and around the heat-affected zone. The CTEs measured from the Invar bead were lower than those from the other sections with the largest and smallest thermal expansion values being 10.40 μm/m-K and 2.09 μm/m-K. In each of the sections, the largest CTE was measured from samples taken from the end of the weld beads. An additional test was performed to measure the aggregate expansion of multi-material tools. Invar beads were welded on an A36 steel plate. The invar was machined, and the sample was heated in an oven from 40 °C and 160 °C. Strain gauges were placed on the surface of the part and were used to analyze how the combined thermal expansions of the invar and steel would affect the thermal expansion on the surface of a tool. There were small deviations between the expansion values measured by gauges placed in different orientations, and the elongation of the sample was greatest along the dimension containing a larger percentage of steel. On average, the expansion of the machined Invar surface was 42% less than the expansion of the steel surface. The results of this work demonstrate that additively manufactured Invar can be utilized to decrease the CTE for multi-material part tooling.
36 MATERIALS SCIENCE↗
Additive Manufacturing of Stamping Tools for Appliances
Oak Ridge National Laboratory (ORNL) worked with Whirlpool Corporation to demonstrate additive manufacturing (AM) of stamping dies for the appliance industry using a large-scale wire arc metal additive manufacturing system jointly developed between Lincoln Electric and ORNL. An appliance stamping die was successfully printed, machined, nitrided, and demonstrated in the last quarter of 2019.
42 ENGINEERING↗