In injection molding, what is the sprue?

In injection molding, the sprue is the channel through which the molten material enters the mold cavity. Its primary function is to guide the liquid material from the injection unit into the mold itself, ensuring that it fills the cavity correctly and efficiently. The sprue needs to be designed effectively to minimize issues such as flow resistance or air trapping, which can affect the quality of the final product.

The importance of the sprue cannot be understated, as it directly influences the performance of the molding process and the characteristics of the molded part. Understanding this component is crucial for tool and die makers, as it affects not only the initial filling of the mold but also the overall efficiency of the injection molding process.

Other options refer to different aspects of the injection molding process. The final product of the injection process pertains to the completed item, whereas a measurement for the mold's thickness is concerned with the structural integrity of the mold itself. The part that holds the mold together relates to components that maintain the assembly of the mold during operation, which is separate from the function of the sprue.