Injection molding process, the holding stage
Injection moldingProcess were divided into the four stages directly decides the forming quality of products, and the four phase is a complete process continuously.The followingDalian injection moldingCompany to introduce in detail the four phases for everyone.
意甲下注The second stage: the holding stage
The role of the holding stage is a continuous pressure, compaction melt, increase the density of the plastic (secret), to compensate for the shrinkage of the plastic behavior.In the process of pressure, because of the mould cavity is filled with plastic, high back pressure.In the process of compaction pressure, injection molding machine screw can only make tiny movement forward slowly, the plastic flow speed is relatively slow, then the current called the holding current.Because in the holding stage, plastic mold cooling solidification is accelerated, the melt viscosity increase quickly, so the resistance within the mold cavity is very large.In the late stage of pressure, material density increased continuously, also gradually forming, plastic pressure maintaining phase will continue until gate seal curing, at this time the holding stage, the cavity pressure peak.
In the holding stage, due to the high pressure, plastic part present compressible characteristics.In high pressure region, plastic is relatively compact, high density;In the low pressure area, the plastic is relatively loose, low density, thus causing density distribution with changing position and time.Flow pressure in the process of plastic flow rate is extremely low, no longer play a leading role;Pressure of the main factors affecting the holding process.Plastic has been full of cavity pressure maintaining process, gradually solidified melt at this time as the transfer medium of pressure.The pressure in the cavity with plastic to the surface of the wall, has a tendency to open mould, so need proper clamping force of clamping.Higher mold force in normal circumstances will slightly will open the mould, exhaust has helped to mould;But if the mold force is too large, easy to cause flash, flash, moulded even open mold.So when choosing injection molding machine, should choose to have a large enough clamping force of injection molding machine, and can effectively protect die in order to prevent the rise of pressure.