Molding Plastic – The Basic Requirements For The Process

2017-03-23 - 00:26 | News | Tags: |

The main requirement, which is presented in injection molding, is to provide the required temperature in injection molding with a maximum uniformity in size and provision of a minimum content destruktirovannogo material prepared for the formation of portions of the alloy. To meet this requirement are selected design of the injection site and the mode in injection molding. Processes in injection molding in injection cylinder piston and screw type differs substantially. Plastic injection molding in a cylinder piston type is carried out mainly by heat from external heat sources. Casting plastic during the passage of the cylinder, plastic slightly mixed, and therefore has a noticeable temperature fluctuations in cross-section portion and along its length. Molding of plastic in the screw cylinder as a result of heat transfer from the external heater and cylinder under internal heat produced during its shear deformation in the channels of the auger.

In plastikatorah screw injection molding subjected to vigorous stirring. It evens out the temperature over the cross section prepared portions for molding plastics. However, some of the temperature inhomogeneity in the plastic molding along the portions prepared for injection, is preserved. In injection molding flow following physical processes: heating, melting, changing the volume of plastic under the influence of temperature (thermal expansion), compression of the melt and compaction of granules or powder (as a result of changes in the depth of the screw channel at a constant step or change pitch at a constant depth, and external pressure), shear deformation of the plastic. Just when casting Plastics can take place, the destruction processes. In injection molding processes are mainly determined by thermal properties of plastics, the parameters determining the heating process (heat conduction, diffusivity, in particular, the specific teploemkoeib). As important parameters in injection molding, which determine the melting process, the parameters of volume expansion and contraction, processes determining changes in the volume of plastics in injection molding.