What are the factors that affect the accuracy of two-color injection molding?

Two-color injection molding is an operation method in which two different colors of the same plastic are plasticized through two barrels, and then injected through the same nozzle at the same time or successively. Using two injection molding machines or two-color injection molding machines for molding, various products with mixed color patterns can be produced, and products with obvious color separation can also be produced. However, if the accuracy of the mold processing and manufacturing process is affected, it will affect the finished product. Then, what are the factors that affect the accuracy of two-color injection molding?

1. Position accuracy
Refers to the actual position accuracy difference between the relevant surfaces of the parts after two-color injection molding. There are eight items for evaluating position accuracy: parallelism, perpendicularity, inclination, concentricity, symmetry, position, circular runout, and full runout. The position accuracy is controlled by the position tolerance, and the position tolerance of each item is also divided into twelve accuracy levels.

2. Dimensional accuracy
Refers to the degree of conformity between the actual size of the processed part and the center of the tolerance zone of the part size. The dimensional accuracy is controlled by the dimensional tolerance. The dimensional tolerance is the allowable amount of variation in the size of the part during mold processing. In the case of the same basic size, the smaller the dimensional tolerance and the higher the dimensional accuracy.

3. Shape accuracy
Refers to the degree of conformity between the actual geometric shape of the part surface after mold processing and the ideal geometric shape. There are 6 items for evaluating shape accuracy, such as straightness, flatness, roundness, cylindricity, and line profile. The shape accuracy is controlled by the shape tolerance. The shape tolerances are divided into twelve accuracy levels except for the roundness and cylindricity divided into thirteen accuracy levels. Level 1 is the highest and level 12 is the lowest.

The above are the main factors that affect the accuracy of two-color injection molding. Generally, when designing machine parts and specifying the machining accuracy of parts, attention should be paid to controlling the shape error within the position tolerance, and the position error should be less than the dimensional tolerance. That is, precision parts or important surfaces of parts, the shape accuracy requirements should be higher than the position accuracy requirements, and the position accuracy requirements should be higher than the dimensional accuracy requirements.