No-Flow Temperature in Injection Molding Simulation

Most injection molding simulation packages use the no-flow temperature (NFT) as a means of determining whether the polymer flows or is solid. The NFT is not well defined, and a standard method for measuring it does not exist. A sensitivity analysis of the filling stage has been carried out with two different packages [VISI Flow (Vero Software Limited, Gloucestershire, UK) and Moldflow (Autodesk, Inc., San Rafael, CA)] to estimate the influence of the NFT on the main processing parameters. The NFT has a large influence on the thickness of the frozen layer, but it does not appreciably affect the filling pressure. Because the NFT affects the frozen layer, an effect on the estimation of shrinka…

The concept and the application of no-flow temperature (NFT) in simulation of injection moulding

No-flow temperature and solidification in injection molding simulation

The no‐flow temperature (NFT) is a parameter representing the rheological solidification temperature of a polymer. A polymer, during injection molding filling stage, can stop its flow because of its high viscosity, although it is not yet fully solidified by means of glass transition or crystallization. The NFT is used in most of injection molding simulation packages: with this simple parameter it is possible to reduce the errors deriving from viscosity extrapolation at relatively low temperatures. The viscosity measurements for polymers are usually carried out at high temperatures, and the viscosity models can fail in prediction at temperatures close to the glass transition or crystallizati…

A study via simulation of solidification during injection molding

The final properties of an injection-molded part are strictly dependent on the solidification dynamics occurring during the processing. The experimental derivation of information about polymer solidification throughout the injection molding cycle is still an open challenge. To overcome the practical issues, the process simulation is proposed as a mean to derive useful data, and especially for identifying the most influencing parameters. The no-flow temperature (NFT) is a parameter used in most of injection molding simulation packages as a mean to determine whether the polymer flows or it is solid. With this simple parameter it is possible to take into account the rheological solidification …