0769-8539-0209 / +86-15158220988
Key points of plastic injection mold runner system

Key points of plastic injection mold runner system

The sub-runner is a transitional channel between the main runner and the gate, as the sub-runner is the longgest part of gating system, so it is very important to enhance the parts quality and improve the productivity by reducing sub-runner process and flow resistance.

Sub-runner requirements:

① Bring the air in the gating system and the cold material at the front side of the melt into the cavity as less as possible to improve the molding quality.

②The runner resistance to the melt should be small, and the volume flow rate should be large to reduce the pressure and temperature loss when the melt flows through the runner.

③The solidification time of the runner should be later than the solidification time of the melt in the cavity to facilitate feeding.

④Ensure that the melt enters each cavity or every corner of the same cavity quickly and evenly.

⑤ The length of the runner should be as short as possible, and its volume should be as small as possible.

⑥The shape and size should be convenient for processing and tool selection.

⑦The upper-level runner is 10%~20% larger than the next-level runner.

Factors affecting the sub-runner design:

①The geometric shape, wall thickness, size, stability, internal quality and appearance quality requirements of plastic parts.

②The variety of plastics, that is the fluidity, melting temperature and melting temperature range, solidification temperature and shrinkage rate of the plastic.

③The pressure, heating temperature and injection speed of the injection molding machine.

④ Falling off method of main runner sub runner.

⑤The cavity layout, the gate location and type.

Key points of sub-runner design:

Cross-sectional area: as small as possible under the conditions of the injection process.

Distribution: compact and symmetrical, minimize the total area of the forming area.

Shape: The ratio of cross-sectional area to perimeter is as big as possible.

Length: as short as possible; the length of the runners of each cavity should be as equal as possible.

Steering: as few times as possible and rounded transitions.

Roughness of the inner surface: It is not necessary to be very light, so that the outer layer of the material flow forms a cooling layer for heat preservation, Ra=0.8~1.6μm.

Condensate ejection: This is particularly desirable when a sprue puffier is used when sub-runner is in cavity side or it is long.

The end of the sub-runner should be provided with a cold well and exhausting-slot .


Tags: Injection Molding | Mold Factory | Mold Supplier | Injection Molding Factory | Injection Molding Supplier | Injection Mold | Injection Mold Supplier | Injection Mold Factory |
Related News about USM Injection Mold
  • Plastic cooling factors by injection parameter

    Plastic cooling factors by injection parameter

    February 11, 20221. Plastic parts design: mainly for the wall thickness of plastic products. The thicker thickness of the product, the longer the cooling time. Generally speaking, the cooling time is approximately pro...view
  • Plastic injection mold heating

    Plastic injection mold heating

    February 17, 2022When the plastic injection molding process requires the mold temperature to be above 80°C, a temperature adjustment system with heating function must be provided in the mold. In addition, thermoplast...view
  • Water assisted injection molding introduction

    Water assisted injection molding introduction

    May 12, 2022Like the gas-assisted injection molding process, water-assisted injection molding injects a piece of plastic into the mold cavity and core firstly, and then injects water to squeeze the melt plastic b...view
  • Temperature system of injection mold

    Temperature system of injection mold

    February 9, 2022Hi everyone,the mold cooling time is the longest during injection, so the design of mold temperature system controlling is very important, we will talk about mold cooling, heating system in following 10 blog.view
  • The main reasons for air trapping of plastic injecton mold

    The main reasons for air trapping of plastic injecton mold

    March 2, 2022During the injection molding process, the front end of the slight ribs may be air trapped and plastic burnt, and also cause the molded part may become black and carbonized.The mechanism of air trapped...view
  • Design Tips of Vacuum Venting Mold

    Design Tips of Vacuum Venting Mold

    March 31, 2022There are some regular venting way which are parting surface venting, insert venting, insert pin venting and well-ventilated steel, but there is a special way is vacumm venting, it will need vacumm ma...view