Title: A study on gas penetration behaviour in gas-assisted powder injection moulding

Authors: Donghan Kim; Hyung Pil Park; Kyehwan Lee; Baeg-Soon Cha; Jae Hyuk Choi; Byung Ohk Rhee

Addresses: Department of Manufacturing Engineering, University of Texas Pan-American, Edinburg, Texas, 78539, USA; Department of Mechanical Engineering, Ajou University, Suwon, 443-749, South Korea ' Department of Mechanical Engineering, Ajou University, Suwon, 443-749, South Korea; Molding & Forming Technology R&D Group, Korea Institute of Industrial Technology, Incheon, 406-840, South Korea ' Department of Manufacturing Engineering, University of Texas Pan-American, Edinburg, Texas, 78539, USA ' Molding & Forming Technology R&D Group, Korea Institute of Industrial Technology, Incheon, 406-840, South Korea ' Department of Mechanical Engineering, Ajou University, Suwon, 443-749, South Korea ' Department of Mechanical Engineering, Ajou University, Suwon, 443-749, South Korea

Abstract: The effects of process parameters on gas penetration depth of gas-assisted injection moulding (GAIM) were investigated for polypropylene (PP) and 316 stainless steel (SUS316L) powder feedstock by the Taguchi method. The process parameters were melt temperature, shot size, gas pressure, and gas delay time. The most significant parameters affecting gas penetration depth were shot size for PP and gas delay time for SUS316L, respectively. The different significance of gas delay time between SUS316L and PP was mainly due to the higher thermal diffusivity and cooling effect of SUS316L as compared to PP. Simulation was also conducted to compare the thermal and rheological properties of materials and to analyse gas penetration behaviour. The higher thermal diffusivity and cooling effect of the SUS316L also caused the increase of the viscosity and shear heating for SUS316L at the time of gas injection. Gas fingering behaviour by the shear heating effect was confirmed.

Keywords: powder injection moulding; PIM; gas-assisted injection moulding; GAIM; gas penetration; polypropylene; stainless steel; Taguchi methods; melt temperature; shot size; gas pressure; gas delay time; simulation; rheology thermal diffusivity; cooling effect; viscosity; shear heating; gas fingering.

DOI: 10.1504/IJMPT.2014.059045

International Journal of Materials and Product Technology, 2014 Vol.48 No.1/2/3/4, pp.66 - 79

Received: 04 Feb 2013
Accepted: 05 Oct 2013
Published online: 30 May 2014 *

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