Thesis (MScIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Lomolding is a new process similar to injection moulding. In this thesis a
numerical model of the polymer flow into the cavity is presented. The model
is used to compare the two processes with each other.
Lomolding and injection moulding were modelled numerically with the finite
element method. The model was an axisymmetric model and takes phenomena
such as generalised Newtonian flow, free surfaces, moving boundaries
and solidification into account.
The processes’ characteristics that were compared are the cavity pressure,
shear rate and shear stress. Improvements in these characteristics will result in
lomolding having smaller machines, less fibre breakage and a better potential
for in-mould-decoration. The thesis shows that lomolding has substantially
lower shear rates and shear stresses than injection moulding. The model was
also used to investigate certain machine design aspects, and to gain a better
understanding of the polymer flow in lomolding. / AFRIKAANSE OPSOMMING: Lomoldering is ’n nuwe proses soortgelyk aan inspuitgiet. Hierdie tesis beskou
’n numeriese model van die polimeervloei soos dit in die gietholte invloei. Die
model word gebruik om die twee prosesse met mekaar te vergelyk.
Lomoldering en inspuitgiet is numeries gemodeleer met die eindige-elementmetode.
Die model is aksiaal-simmetries en neem verskynsels soos Newtoniese
vloei, vrye oppervlakke, bewegende grense en stolling in ag.
Die proses-karakteristieke wat vergelyk is, sluit die gietholtedruk, vervormingstempo
en skuifspanning in. Verbeterings in hierdie karakteristieke sal
meebring dat lomoldering kleiner masjiene nodig sal hê, minder veselskade sal
veroorsaak en meer versoenbaar met in-gietholte-versierings sal wees, vergeleke
met inspuitgiet. Die tesis toon dat lomoldering laer vervormingstempo’s en
skuifspanning het, in vergelyking met inspuitgiet. Die model is ook gebruik
om sekere masjienontwerpaspekte te ondersoek, en om die polimeervloei in
lomoldering beter te verstaan.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/16318 |
| Date | 12 1900 |
| Creators | Dymond, Jacques Andrew Dryden |
| Contributors | Basson, A. H., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xviii, 131 leaves : ill. |
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