Injection mold structure: cold runner
author: Universe plastic
2024-06-05
The cold runner is a runner structure in the injection mold. The runner has no heating system and its function is to guide the molten plastic from the nozzle of the injection molding machine to the mold cavity for cooling and molding.
Cold runner molds are widely used in the production of a variety of plastic products. The following is a detailed introduction by Universe Plastics engineers on the composition of the cold runner structure and its functional advantages and disadvantages:

Cold runner structure composition
1. Main channel
The main channel connects the nozzle of the injection molding machine and the shunt channel of the mold. It is the main channel for the plastic melt to enter the mold. Usually the main channel has a larger inlet to adapt to the injection molding machine nozzle, and gradually reduces the diameter to reduce the resistance of the melt during the flow process.
2. Diversion channel
The runner distributes the plastic melt from the main channel to the gates of each mold cavity. The runner design can be balanced or unbalanced, depending on the number of cavities and layout of the mold. The shape of the shunt can be circular, semicircular or trapezoidal, and usually there are circular or trapezoidal shapes because they have less flow resistance.
3. Gate
The gate is the final passage for plastic to enter the mold cavity and is usually the smallest part of the entire cold runner system. The design and location of the gate have a great impact on the quality of the finished product, which affects the filling, cooling and demoulding of the plastic.
4. Cold well
The cold well is a blind hole located at the junction of the main channel and the runner. It is used to collect the plastic melt that cools quickly to prevent it from entering the mold cavity and affecting the quality of the product.
Advantages and disadvantages of cold runner structure
Advantages: The cold runner system has a simple structure, low processing and manufacturing costs, and is suitable for low-cost and small-volume injection molding production.
Disadvantages: The molten plastic in the cold runner needs to be manually removed and recycled in every production, which easily causes material waste and low production efficiency.
Summarize
The cold runner structure is not complicated in the production of injection molds. It can realize the low-cost injection molding production of most plastic products and is very popular in practical applications.
Dongguan Universe Plastic Factory has more than 15 years of experience in manufacturing injection molds. It has a professional team and processing equipment to provide high-quality and cost-effective injection mold manufacturing services.
If you have injection mold customization needs, please contact us to get the latest service quotation.
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