Mould filling condition

Equation (4.50) implies that, under the conditions of Eq. (4.50), the mould filling time is given by ... 

The process of mould filling should not be considered as completely understood and controlled 98>, though some important features of gas-filled system flow were established by Fridman and co-workers 99 100) who have explained the formation of laminated structures in low-pressure moulding of foaming melts and found the correlation between moulding conditions and morphologic macro-structure and properties of foam articles. 

Under normal processing conditions the surface of the moulded part always has a swirl pattern. This occurs on mould filling and is due to the collapse of the foam cells as they come into contact with the cold mould surface. 

For manifold design or selection, the following conditions should be met provision of identical cavity filling conditions in multi-cavity moulds minimisation of pressure losses in manifold channels ... 

The manufacture of products, e.g. containers and lids, made from filled foamed PE by gas counter pressure injection moulding was studied with special reference to the effect of production conditions on dimensional stability. Results obtained are discussed and evaluated. 7 refs. 

An alternative form of non-carbonated beverage comes in form-fill-seal plastic containers, which are typically square or round section cups with foil or plastic laminate lidding. Such products are difficult to produce to a quality that will satisfactorily compete with the shelf fife of aseptic foil/laminate packs. Fonn-fill-seal containers leave their contents vulnerable to oxidative degradation and are especially at risk of mould spoilage. The packs can be produced in aseptic conditions but the products are typically chemically preserved. 

This issue has been addressed by the second type of aseptic filling system in which a polyethylene bottle (which can be multi-layered to add a gas or light barrier) is moulded under sterile conditions. While the bottle is still sterile, and the polyethylene is soft, the trim material above the neck finish (moil) is crimped closed to seal the bottle. The sealed, sterile, empty bottle can then be packed and transported to a filling line, which may be in another location from... 

Equation (4.23) holds true when H/q0 > e1/s. The existance of 5+, which minimizes the filling time for radial forming cavity, is conditioned by the same physical (hydrodynamical) reasons as in the case of a flat moulding. 

The mouldability index is the length of the elongated flow path that is filled before solidification of the injected molten polymer composition at specified moulding conditions, i.e., volumetric injection rate, mould temperature, polymer melt temperature. The mouldability index of the moulding compositions of this invention is characterised by spiral flow. 

---