Two-color mold: Two kinds of plastic materials are injected on the same injection molding machine, which is divided into two moldings, but the product is only used for one-time molding. In general, this molding process is also referred to as two-shot molding and is usually completed by a set of molds and requires a special two-color injection molding machine.
Plastic lagging mold (secondary molding): two kinds of plastic materials are not necessarily injected on the same injection molding machine and are divided into two moldings; the product is taken out of the mold from one set of molds, and then put into another set of molds for the second Injection molding. Therefore, in general, this molding process is usually completed by 2 sets of molds without the need for a special two-color injection molding machine.
Overmolding mold (overmold) and two-color mold overview
In the design of the overmolding mold, attention should be paid to the positioning of the hard plastic parts, and a reliable sealant must be provided, and a reverse tilt hole is provided on the plastic parts to prevent the plastic deformation.
Two-color molds are increasingly popular on the market. This process can make the appearance of products more beautiful, easy to change the color and can not spray, but the cost is expensive and technical requirements are high.
1. The two shapes of Cavity are different, and one type of product is formed separately. The two shapes of the Core are exactly the same.
2. Before and after the mould is rotated 180o centered, it must match. This check must be done at design time.
3. Note the position of the thimble hole, minimum distance 210mm. Large molds must be properly increased in the number of holes in the top bar. In addition, because the ejector attached to the injection molding machine itself is not long enough, an extended ejector pin must be designed in our mold, and the ejector pin should be about 150 mm long. Two positioning rings must be designed on the rear mold base plate.
4. The total thickness of the front mold panel plus A plate must not be less than 170mm. Please check the other reference data of this type of injection molding machine carefully, for example, the maximum mold thickness, the minimum mold thickness, the top hole distance and so on.
5. The nozzle of the three-platen die can be designed to automatically release the die. Special attention should be paid to whether the release of the soft glue mouth is reliable.
6. The depth of the front SPRUE should not exceed 65mm. The distance from the top of the SPRUE on the upper side to the center of the mold blank is not less than 150mm.
7. In the design of the second injection of CAVITY, in order to avoid CAVITY insert (or wipe) injury to the first product has been formed into a good product, you can design part of the avoidance. However, the strength of each sealant must be carefully considered. That is, if there is a large injection pressure under plastic injection, the plastic will deform, which may result in the possibility of a second front injection.
8. When injection molding, the size of the first injection molded product can be slightly larger, so that it can be pressed tighter with another CAVITY during the second molding to achieve the effect of sealing.
9. In the second injection molding, does the flow of plastic impetus the first-formed product to deform the gel position? If this is possible, it must be improved.
10. Before closing the A and B plates, please pay attention to whether the front mold Slider or Lifter will reset and crush the product first. In this case, you must find a way to make the A and B plates clamp before the SLIDER or LIFET of the front mold. Reset.
11. The transport arrangements of both CAVITY and CORE are as full and balanced as possible.
12. In 99% of the cases, the hard plastic portion of the injection molded product was first injected, and the soft plastic portion of the injection molded product was re-injected. Because soft plastic deformation.
13. In order to "tighten" the two plastics more closely, consider the "stickiness" between the materials and the roughness of the mold surface. Two-color injection molding has a special TPU; the smoother the mold surface, they "stick more tightly.
14. Pay attention to the positioning of the front and rear molds; the slope of all the plug-in and break surfaces should be as large as possible, and should be 0.1mm or more.