In general, the shrinkage of two-color molds depends on the primary material. Because the primary material already holds the contour of the plastic, the secondary material does not shrink more. As to how to determine primary and secondary materials, there are many factors to consider, such as the flow of raw materials, the shape of plastics, and so on.
For a two-color mold, if it is only trapped, the same rubber material is easy to handle, and the shrinkage of the material is the same. If it is not the same material, the shrinkage of the two rubber materials is not the same. If the ratio cannot be maintained, it will be deformed. If the hard rubber is 0.005, soft rubber is 0.018, according to the respective shrinking water, not a lot of soft plastic will be a lot, all touch perforation column position are not shifted, if not according to their release, will not do soft rubber part The size that comes out will be much smaller, it doesn't matter if the size is small, and if it's too big, it will be troublesome.
The solution is that if the two shrink, 0.005 and 0.018, directly by 0.005, shrink hard glue to put it. As for the soft rubber part of the shrink, how to correct it? Soft rubber compound, in general, will not exceed 2MM, more than certainly will shrink, so that the difference between his shrink is the thickness of this 2MM, rather than what we routinely think. If there is a difference in the height of the soft rubber, there should be a shrink in the Z direction. Because of the presence of hard glue, the shrinkage of the soft material in the Z direction was blocked, and there was no place for him to deform.