Powder injection molding requires the master and control of injection parameters in order to produce high-quality green parts. This work combines experimental and numerical approaches to study the impact of injection parameters on mold in-cavity pressure and overall quality of green parts produced by low-pressure powder injection molding. Properties of two lowviscosity feedstocks (formulated from a water-atomized stainless-steel powder and wax-based binder system) were measured and implemented into an Autodesk Moldflow numerical model to quantify the molding pressures that were finally validated using experimental real-scale injections. The results confirmed that an increase in mold temperature, an increase in feedstock temperature, and a decrease in solid loading decrease the mold in-cavity pressure that was also correlated with the feedstock viscosity. As a key result, real-scale injections confirmed that a minimum flow rate was required to avoid early solidification, atypical high in-cavity pressure, and several visual defects such as weld lines, flow marks, cracks, sinks, and incomplete filling. Due to difference in its thermal properties, this flow rate threshold value decreases as the feedstock solid loading increases. For injection speeds higher than this flow rate threshold value, the injection pressure measured experimentally in a simple rectangular cavity (almost constant shear rate) was linearly correlated with the injection flow rate.
| Date | 10 Nov 2022 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Vincent Demers (Supervisor) |
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Arès, F. (Author),
Demers (Supervisor),
10 Nov 2022Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering