Reasons for the difference between cold and hot runners

　　Cold and hot runners are channels used to guide plastic flow in the mold during injection molding.They have the following differences in construction and functionality:

1. Temperature control:The main function of the cold runner is to cool and solidify the plastic during the injection molding process,ensuring product quality.Therefore,the cold channel needs to be controlled by a cooling system to ensure that the plastic can quickly cool and solidify during the flow process.On the contrary,the hot runner is mainly used to heat the plastic in the mold to maintain its fluidity throughout the entire injection process.The hot runner needs to control the temperature of the channel through a heating system to ensure that the plastic can maintain a suitable temperature range throughout the entire injection process.

   
   

　　2.Fluidity:The cold runner has a large cross-sectional area and a longer length,allowing the plastic to fully cool and solidify.Due to the need for cooling effectiveness,a large amount of cooling water is usually used in the cold runner to help reduce temperature.On the contrary,the hot runner has a smaller cross-sectional area and shorter length to quickly heat the plastic and maintain it in a flowing state.The hot runner provides thermal energy through a heater to compensate for heat loss and cooling effectiveness.

　　3.Cost and complexity:Due to the simple structure and cooling system commonly used in cold flow channels,they are relatively inexpensive and easy to operate.Its design and manufacturing process are relatively simple.On the contrary,the design and manufacturing of hot runners are relatively complex,requiring the integration of heaters and temperature control systems into the mold,increasing manufacturing costs and difficulties.

　　4.Application scope:Cold runner is usually suitable for large and complex injection molded parts,as they can provide better cooling effect and reduce product deformation and shrinkage.Hot runners are more suitable for injection molded parts that require high precision and quality,as they can provide better temperature control and plastic fluidity.

　　In summary,the main differences between cold and hot runners lie in their temperature control method,flow performance,manufacturing cost,and applicability.In injection molding,choosing the appropriate type of runner depends on factors such as product requirements,injection molding materials,and production efficiency and cost considerations.