Session: 03-11-02: Laser-Based Advanced Manufacturing and Materials Processing II

Paper Number: 167094

Dimensional Accuracy Study of Additively Manufactured 18Ni300 Maraging Mold Steel 

Injection molds serve as cornerstones of modern manufacturing, supporting mass production across automotive, consumer electronics, and medical device industries. The emerging trend of personalized production requires molds to accommodate frequent design iterations and complex functional features like conformal cooling channels. Particularly, in high-value sectors such as automotive lighting and micro-fluidic device production, manufacturers increasingly demand molds integrating optimized cooling geometries with dimensional tolerances below 50μm. Traditional injection mold fabrication methods not only incur long lead times and high costs for complex mold, but also suffer from limited design flexibility and fail to meet the growing demands for personalized production. As one of the additive manufacturing technologies, the selective laser melting (SLM) demonstrates unique capabilities in product customization due to its high design freedom and rapid prototyping capabilities. For instance, the growing adoption of high-performance polymers and compact product designs necessitates molds with embedded sensor cavities and topology-optimized structures, further highlighting SLM's technological superiority. Therefore, SLM provides an innovative solution for manufacturing injection molds with complex geometries such as conformal cooling channels. In SLM-based mold fabrication, dimensional accuracy critically determines the mold assembly compatibility, cooling system sealing performance, and final product dimensional consistency. However, current researches mainly focus on optimizing fundamental material properties, while the thermomechanical mechanisms governing dimensional accuracy remain insufficiently investigated. In this context, in the present study, cylindrical specimens representing the injection mold inserts were designed and fabricated to elucidate the formation mechanisms of SLM-induced dimensional deviations. The widely used maraging steel (18Ni300) was employed in experiments. Meanwhile, a thermal diffusion model was established using COMSOL Multiphysics package. Combined with dimensional error distribution measurements, this study reveals a height-dependent radial expansion phenomenon in the fabricated specimens, demonstrating a progressive increase in radial dimensions with ascending build height, where the maximum radial deviation reaches ±0.03 mm/10 mm. Moreover, residual stress analysis at multiple height positions revealed compressive stress gradients in the specimen surface layer, demonstrating a positive correlation between dimensional deviations and the compressive stress gradients. In addition, scanning electron microscopy (SEM) characterization and mechanical testing confirmed that phase transformation and residual stress redistribution induced by thermal diffusion are primary factors contributing to dimensional inaccuracies. Vickers hardness testing and nano-indentation further revealed printing-direction-dependent gradients in hardness and elastic modulus, whose spatial distributions exhibit a positive correlation with thermal deformation behavior. The findings in this work provide theoretical supports for developing thermal deformation compensation approach and advanced precision control in SLM-based mold manufacturing.

Presenting Author: Can Yang Shenzhen Technology University

Presenting Author Biography: Dr. Can Yang
He received his B.S. and Ph.D in Mechanical Design and Theory from South China University of Technology in 2006 and 2011, respectively. From October 2008 to September 2010, he was working at The Ohio State University, USA as a visiting scholar with Professors Jose M. Castro and Allen Y. Yi. He is currently working at Shenzhen Technology University, with research interests covering advanced manufacturing, intelligent/high-performance material forming process and equipment.

Authors:

Can Yang Shenzhen Technology University
Yiyang Xu Shenzhen Technology University
Yu Chen Shenzhen Technology University
Zhifu Yao Shenzhen Technology University