A machined substrate hybrid additive manufacturing strategy for injection moulding inserts
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ORIGINAL ARTICLE
A machined substrate hybrid additive manufacturing strategy for injection moulding inserts Yuk Lun Chan1,2
· Olaf Diegel1 · Xun Xu2
Received: 26 May 2020 / Accepted: 5 November 2020 © Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract In recent years, advances in metal additive manufacturing (AM) technology make the fabrication of complex conformal cooling channels for injection mould possible. However, poor surface finish, inadequate dimensional accuracy, and high manufacturing costs impede the technology to be adopted in the mould-making industry as an alternative. In this study, a time-efficient machined substrate hybrid AM strategy was developed for the fabrication of injection mould inserts using a hybrid additive-subtractive powder bed fusion process. The primary goal is to reduce AM build and post-processing time. Pre-machined support-free substrate blocks with position alignment and referencing features for subsequent machining operations were used for the additive manufacturing and high-speed machining processes. Four mould inserts, selected from a production injection mould, were redesigned with conformal cooling channels and fabricated in a metal powder bed fusion system using the standard AM practice and the proposed hybrid-build method. In comparison with the standard AM practice, a considerable saving in processing time was attained, but with a slight compromise in tensile strength. Through optical microscopy (OM) and scanning electron microscopy (SEM), a strong fusion bonding can be seen at the interface boundary between the additive powder and machined substrate. This new strategy will provide mould performance enhancement at reduced manufacturing costs for the plastic products manufacturing industry. Keywords Additive manufacturing · Hybrid additive-subtractive manufacturing · Powder bed fusion · Mechanical properties · Microstructure
1 Introduction Injection moulding is one of the most efficient and widely used manufacturing processes for the mass production of plastic parts. The productivity of this manufacturing process and the unit part cost are governed mainly by the overall moulding cycle time. In practice, the cooling time of the moulding cycle typically amounts to 70 to 80% of the whole cycle [1]. Hence, improving mould cooling performance is one of the most critical challenges in injection mould design and fabrication. The incorporation of conformal cooling
Yuk Lun Chan
[email protected] 1
Creative Design and Additive Manufacturing Lab, The University of Auckland, Auckland, New Zealand
2
Department of Mechanical Engineering, The University of Auckland, Auckland, New Zealand
channels (CCC) in mould inserts is proven to be a solution [2–5]. With the advancement in metal additive manufacturing (AM) technology, such as the powder bed fusion (PBF) process, fabrication of fully dense injection mould inserts with CCC in tool steels has become a reality. Mazur et al. [6] revealed that not only did PBF fabricated mould inserts with CCC from AISI
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