Multiple slot molds are used to connect the main flow path and various cavities during the injection molding process. In order to fill the molten material uniformly in each cavity, the arrangement of the diversion channels on the mold should have symmetry and equidistant distribution. The cross-sectional shape and size of the diversion channel affect the flow of plastic melt, the ease of product demolding, and mold manufacturing. For the same amount of material flow, the flow path resistance on a circular cross-section is small.

However, the cylindrical flow path is smaller than the surface, which is not conducive to cooling the excess material in the flow path during injection mold processing. Moreover, this diversion path must be opened in pairs, which is easy to be complicated and aligned. Therefore, trapezoidal and semi-circular cross-section diversion paths are often used and installed on half of the mold with demolding rods. The surface of the flow path needs to be ground to reduce flow resistance, and the filling speed is fast.

The size of the injection mold processing flow path depends on the type of plastic, the size and thickness of the product. For many thermoplastic materials, the cross-sectional width of the diversion path is below 8m, with some reaching 10-12m for extra large ones and 2-3m for particularly small ones. While meeting the requirements, the cross-sectional area should be minimized as much as possible to avoid the increase of excess material or longer cooling time in the diversion path.

The pathway connecting the main flow path and the cavity. The cross-sectional area of the pathway can be equal to that of the main pathway, but it is usually reduced. Therefore, it is the part with a small cross-sectional area in the entire injection mold processing channel system. The shape and size of the sprue have a significant impact on the quality of the product.

The design of the shape, size, and position of the sprue in injection mold processing depends on the properties of the plastic, the size and structure of the product. The cross-sectional shape of a general gate is rectangular or circular, with a small cross-sectional area and short length. This is not only based on the aforementioned effects, but also because small gates are prone to becoming larger, making it difficult for large gates to shrink. The gate position is usually a place where the product is thick and does not affect its appearance. The design of gate size must consider the properties of plastic melt.