Type

Journal Article

Authors

M. D. Gilchrist
Seong Ying Choi
Quanliang Su
Nan Zhang

Subjects

Engineering

Topics
morphology of micro scale features size induced crystallization process induce crystallization long term mechanical properties micro gate design room temperature product design young s modulus

Effect of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection moldings (2015)

Abstract Miniaturized parts weighing up to tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding cause material to experience high shear rates and high cooling rates, and to have different morphology and final properties from conventional injection moulding. It also makes mould design quite challenging. This study investigates micro gate design (opening and thickness) and cavity thickness (100–500 μm) on filling, morphology and mechanical properties of Poly(ether-block-amide) miniaturized dumbbell parts. It is found that a reduction of gate size has two conflicting effects: increased shear heating increases flow length; increased cooling rate reduces flow length. Filling increases significantly with an increase of cavity thickness. In addition, skin ratio reduces from ∼70% to ∼10%, when part thickness increases from 100 μm to 500 μm. Such oriented skin layer determines molecular orientation and broadly influences Young’s modulus, elongation and yield stress. Natural aging at room temperature induces an increase of modulus and yield stress, and a decrease of strain at break. Mechanical properties of microinjection mouldings are significantly different from conventional injection mouldings and measurement at the microscale is required for successful miniaturized product design.
Collections Ireland -> University College Dublin -> Mechanical & Materials Engineering Research Collection
Ireland -> University College Dublin -> School of Mechanical and Materials Engineering

Full list of authors on original publication

M. D. Gilchrist, Seong Ying Choi, Quanliang Su, Nan Zhang

Experts in our system

1
M. D. Gilchrist
University College Dublin
Total Publications: 172
 
2
Nan Zhang
University College Dublin
Total Publications: 19