The torque wrench socket (with jaws measuring 46.1 mm, a head of ¾”, and outer dimensions of 91 mm) was redesigned for additive manufacturing (AM) by Cyient using Siemens NX and Altair Inspire software. Key objectives included minimizing material usage and part mass while maximizing strength. The optimized design accounted for a torque of 500 Nm with a safety factor of 1.2 and a friction coefficient of 0.15.
Delva fabricated the part using an EOS M270 machine with a standard parameter set and a layer height of 40 µm. The process utilized recycled powder and a ceramic recoater to accommodate the magnetic properties of the material. Pre-manufacturing steps involved preparing the print job, examining printability, positioning the part, and designing support structures.
Post-manufacturing, the part underwent heat treatment at 490°C for 4.5 hours to achieve an ultimate tensile strength of approximately 2000 MPa and hardness of 54-56 HRC. Subsequent steps included sawing off the part from the build plate, removing support structures, shot blasting with steel balls, and ultrasonic cleaning to enhance surface quality.
The part’s dimensions were inspected using a Mitutoyo Crysta-Apex V9106 CMM equipped with both contact and non-contact line laser probes. Critical features like the jaws and head were measured, and a complete object scan was performed to compare the actual part against the 3D model using Mitutoyo MCOSMOS software for precise analysis.
The socket was subjected to its specified torque load and tested in an operational environment for three years. The results were impressive, showcasing the part’s compactness, lightness, and strength compared to the original conventionally manufactured version. Despite a slight dimensional shrinkage during manufacturing and heat treatment, the part performed exceptionally well, withstanding a 500 Nm torque.
The printability of the topologically optimized design was good, and the dimensions of the final part were very well in line with the 3D model without any scaling. Some minor deviations were inspected from the tolerated features of the part.
One of the targets for Design for Additive Manufacturing (DfAM) was to increase the compactness of the part. The weights of the original and optimized AM socket were 843 g and 366 g, respectively. The mass reduction achieved through topology optimization and AM was 57%.
The single AM part’s manufacturing cost was approximately €400, significantly higher than the original part’s €113. However, optimizing printing and post-processing could reduce costs in mass production, with estimates suggesting a reduced cost of €255 per part in serial production. Overall, the functionality of the AM part was significantly better, justifying the higher costs.
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Finnish Additive Manufacturing Ecosystem (FAME) is an innovative industrial ecosystem that brings together key players in the Finnish additive manufacturing field to increase the role of Additive Manufacturing in Finland.
The ecosystem is funded by the participating companies and Business Finland, and is run by DIMECC Oy.
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