Date of Award

4-2020

Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Department

School of Engineering

First Advisor

Dr. C. Pung

Second Advisor

Dr. P. Anyalebechi

Third Advisor

Dr. S. Manoharan

Academic Year

2019/2020

Abstract

Channels where coolant is run to cool a system are common in injection mold tooling. Conventionally, these channels are machined into the mold. This has limited the design of mold cooling systems to the constraints of traditional machining processes, where straight circular channels machined from cast material are typical. The transfer of heat away from the part cavity into these cooling channels has a large effect on the cooling time of the injection mold cycle. In this investigation, laser powder bed fusion processes were used to create non-circular cooling channels. To compare cooling performance, elliptical and circular channels of equal crosssectional area were investigated for mass flow rate and rate of heat transfer. Between conventionally machined and additively manufactured channels, surface roughness of the channel wall and condition of the parent material were investigated as potential factors as well. Through simulation, analysis of channel surface roughness, and experimentation, the results indicated that: the channel machined from cast 316L stainless steel had higher flow rate and rate of heat transfer compared to the machined channel fabricated from selective laser melting 316L metal powder, the machined channel had higher flow rate and rate of heat transfer compared to the as-fabricated additively manufactured sample, and the circular additively manufactured channel had higher flow rate and rate of heat transfer compared to the elliptical channel. Overall, the traditionally machined circular channels had superior cooling performance than the additively manufactured elliptical channels. However, the results demonstrate that changing the length-to-width ratio of elliptical cross channels can be used to locally control cooling on regions of the part to reduce hot-spots in the mold and part defects.

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