Basic Principles Of Die Runner Design- Taizhou Huangyan Aoxu Mould Technology Co., Ltd.

Terminal: also called main runner, Sprue, or vertical runner, it refers to the flow channel from the part where the ejector nozzle is in contact with the main channel bushing of the die to the diverging channel.
This part is the first part that flows through the molten plastic after it enters the mold.
Both the First Runner and the second Runner can be further divided with the die design.
The diverging channel is the transition zone between the main channel and the gate, which can make the flow direction of the molten plastic get a smooth transition.
For multi - hole mould, it has the function of distributing plastic evenly to each hole.
Ending gate: also called inlet.
It is a narrow opening between the shunt passage and the die hole, and it is also the smallest part with thin meat.
The effect is to accelerate the plastic by using the tight flow surface. High shear rate can make the plastic flow well.
The heating effect of viscous heating can also increase the temperature of the material and reduce the viscosity.
The gate is first solidified and sealed after the completion of molding. It can prevent the plastic from flowing back and the pressure of the hole from falling too fast to cause the forming products to shrink and sag.
After forming, it is convenient to cut off and separate runner system and plastic parts.
Ending cold charge well: also called cold charge hole.
The purpose is to store and collect the cold plastic wave before the initial stage of filling and filling, so as to prevent the cold material from directly entering the hole to affect the filling quality or block the gate. The cold material well is usually set at the end of the main channel.
Basic design principles
Cavity Layout considerations
Try to arranged balance type low (Balances Layout).
The arrangement of the die hole and the opening of the gate strive to be symmetrical, so as to prevent the problem of supporting die overflow caused by unbalanced force on the die.
The design shown in figure 2 is more symmetrical.
The squeeze hole arrangement is as compact as possible to minimize mold size.
The design of figure 3(b) is superior to that of figure 3(b) in terms of mold size.
Flow guidance considerations
The mixture can guide the molten plastic to fill the die hole smoothly, without eddy current, and can discharge smoothly.
In order to prevent Core Shift or deformation, the plastic melt front impact Core and metal insert with smaller diameter are avoided as far as possible.
Consideration of heat loss and pressure drop
The smaller the heat loss and pressure drop, the better.
The ending flow is shorter.
The length of the nozzle channel should be large enough.
Avoid bend and sudden change of flow direction (change direction with arc Angle).
The surface roughness of the nozzle runner is low.
Pressure drop and required ejection pressure can be reduced with multi-point injection, but there will be stitching problems.
Consideration of flow equilibrium
When filling with multi-cavity of one module (multi-cavity), the flow channel should be balanced and the plastic should be filled with each Cavity at the same time to ensure the quality consistency of the moulding products of each Cavity.
Natural Balanced Layout (Naturally Balanced Layout) should be adopted as far as possible in the bypass.
Manual balance method is used to balance the flow channel when natural balance cannot be achieved.
Waste consideration
With the advantages of smooth filling without affecting flow and pressure loss, the volume (length or cross-sectional area size) of the runner can be reduced to reduce waste generation and recovery costs.
Cold material consideration
The Cold Slug Well and overflow tank are designed to fill the Cold plastic wave at the initial stage of filling in the flow channel system, so as to prevent the Cold material from entering the cavity directly and affecting the filling quality.
Exhaust considerations
Both ends should guide the plastic to fill the hole and allow the air inside the hole to escape smoothly to avoid the problem of sealing and burning.
Consideration of forming quality
Shorter ejection, hairline, sealing, stitching line, flow mark, jet flow, residual stress, warping deformation, die core deviation and other problems are avoided.
The warping deformation of finished products caused by flow imbalance, insufficient pressure protection or uneven shrinkage should be prevented when the flow of the circulating channel system is long or Multiple Gating.
The appearance of the product is good, and the dressing Gate is easy to remove. Gate Mark does not damage the appearance and application of the parts.
Productivity considerations
The machining cycle is shortened and the production efficiency is improved.
Let's think about it a little bit
The proper ejection position should be considered to avoid deforming of the forming part.
Consideration of using plastic
The plastics with higher viscosity or shorter L/t should avoid using too long or too small size runner.