The flow rate of the melt varies over the wall thickness during filling.
Shear forces arise between the layers of different velocities.
This way a thought volume element is deformed (diamond in the picture).
The time dependent change of the angle (gamma) is called shear rate.
High shear rates lead to shear heating, molecular chains deform and might break.
The quality of the product is reduced.
With this gate design, the plastic melt is introduced into a mostly rotationally symmetrical part area through several radially arranged feed sections. The spoke-shaped distribution supports uniform filling of ring-, disc-, cup-, or sleeve-shaped injection molded parts and can significantly shorten the flow path compared with one-sided gating. The spoke-umbrella gate is often used when central gating is not sufficient from a design perspective or when better melt distribution around the circumference is required. The number, cross section, and position of the individual spokes influence pressure loss, flow front formation, weld lines, part orientation, and shrinkage behavior. After injection molding, the spoke-shaped gate residues usually have to be removed from the part mechanically or through predefined separation points.
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In this type of feed system, the plastic melt reaches the injection molded part through a rod-shaped sprue, either directly or via a simple runner system. It typically forms as a cylindrical or tapered solidified residue in the sprue channel and is separated from the molded part after ejection. The sprue bar is mainly relevant in conventional cold-runner molds because it is ejected together with the part and must then be recycled or discarded. Its geometry affects pressure loss, filling behavior, solidification time, and material consumption in the injection molding process. Proper design supports stable mold filling and helps reduce scrap and post-processing.
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This term refers to a specific gate design used in injection molding that is based on a conventional edge gate but includes an additional section of cold runner connected perpendicular to the gate. This additional section serves to reduce the velocity of the polymer melt before it enters the mold cavity. By lowering the initial melt front speed, a more controlled and uniform flow into the cavity can be achieved, helping to prevent molding defects such as jetting. The additional runner section acts as a buffer zone in which the melt flow stabilizes before entering the cavity. For optimal performance, the design of this gate type is often developed using flow simulation to avoid issues such as flow hesitation or excessive melt front velocity.
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The injection molding process highly depends on temperature.
If the molten plastic enters the cavity the temperature is high and sequentially decreasing overtime.
The reduction in temperature is based on the given cooling layout of the mold and the process parameters set.
In simulation the temperature result shows temperature distribution of the part and mold at current instant.
It can help to evaluate temperature related aspects of the process, for instance, hot spot.
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