33. In general, the shrinkage rate of a two-color mold depends on the primary material. Since the primary material already supports the contour of the plastic product, the secondary material does not shrink more. As for how to determine the primary and secondary materials, there are many factors to consider, such as the fluidity of the raw materials, the shape of the plastic products, and so on.
34. Pay attention to the positioning of the front and rear molds; all the insertion and the slope of the broken surface should be as large as possible, and should be 0.1mm or more.
35. ABS/PC, ABS/PC+ABS, ABS/PMMA two-color injection molding, it is necessary to first injection high temperature PC, PC+ABS or PMMA. In the case of a transparent face shell mold, most of the flip mold structures are used.
36. Transparent large two-color injection molding is a place to pay attention to structural design:
(1) The reservation of the gate location must be agreed in advance with the mold factory.
(2) The thickness of the material is recommended to be transparent 0.8mm or more, non-transparent 0.7mm or more, non-transparent as far as possible to use light color, when there is LED light, pay attention to shading.
(3) The width of the parting surface of the transparent part and the hole are the same, the width is recommended to be 0.5mm, the curved surface is smooth, avoiding the side view, can pass through far, not beautiful, and minimize the hole.
(4) The thickness of the non-transparent parts is limited, and the structure of the upper ribs and the like is as much as possible between 0.5 and 0.6 mm to avoid shrinkage.
(5) For the time being, it is not recommended to do two-color injection molding with main lens. The cost of mold and product is too high. There is considerable demand for the equipment and technical level of the mold manufacturer. If you do, you need to give the whole process a detailed solution. The program is for evaluation and the intermediate links need to be reviewed.
(6) For large-area two-color injection molded parts, two key tests are drop and thermal shock. In both tests, the transparent and non-transparent parts are easily disengaged. Hot and cold shock -40 -65, time 48 hours.
(7) The structure on the two-color parts should be as simple as possible, and the complex parts should be made above the matching parts. The width of the ribs of the non-transparent parts should be 0.5-0.6mm as much as possible to avoid shrinkage.