I believe that is a BUMP in the clamp during the injection phase when molding rubber or silicone. The clamp is allowed to breathe (reduce tonnage) to expel the air trapped inside the mold. The clamp can be opened and closed ever so slightly (i.e. BUMPED) during the filling/pack phase of injection. This can also help to reduce molded in stress. The majority of press manufactures that have accurate control over their clamp movement can add this option to their control for a charge.
The compressional motion can be done by injection compression molding machine itself or separate mechanism linked with traditional injection molding machine. The mechanism is normally hydraulic-designed. It pushes mold plates or necessary cores to compress prior-filled melt then a finished part is made. To complete a process cycle, the mechanism is normally also integrated/programmed with injection molding machine so that its actuation/ending timing signal of compressional motion can be sent from/to injection molding machine.
The compressional motion can be done by injection compression molding machine itself or separate mechanism linked with traditional injection molding machine. The mechanism is normally hydraulic-designed. It pushes mold plates or necessary cores to compress prior-filled melt then a finished part is made. To complete a process cycle, the mechanism is normally also integrated/programmed with injection molding machine so that its actuation/ending timing signal of compressional motion can be sent from/to injection molding machine.
Die casting is a process in which the liquid metal or semi-liquid metal is forced into a reusable die very fast with high pressure and temperature.
Molten metal is injected into steel dies, high pressure ensure molten metal fills the empty space between the die halves, while metal is held in the die, it solidifies and cools, when solidification and cooling is completed, the die is opened, then the solid die casting is ejected. Die casting parts are usually made of aluminum, zinc alloy, it's much strong than plastic molded parts, parts made by die casting is widely employed in many different industries.
I have seen hot runner internally flooded with plastic because injection parameters and settings are wrong. For example: mold cavity fill time too long, which causes the material to freeze up close to the injection points; then hold pressure applied onto frozen injection points—> the molten plastic has to go somewhere, maybe into your hot runner. A good symptom for this problem is if you have material leakage at the main mould entry valve gate and plastic creeping back up your screw cylinder - because the molten material cannot get into the frozen cavity.
