What is the difference between two-color mold and over mold?
A. two-color mold:
Two-color mold or ‘two-shot’ injection moulding consists of processing two different polymers (or two different colors of one polymer) into an end product by means of one injection moulding process. This technology enables several functions to be integrated into an injection moulded product.
Two plastic materials in the same injection molding machine, molded twice, but the product is only a mold. This molding process is also commonly referred to as double injection molding, usually done by a set of molds, and requires a dedicated two-color injection molding machine
B. Over mold (overmolding):
What is overmolding?
Overmolding is an operation in which two or more mediums or substances are merged to form an item or alloy. An item that is overmolded is usually made up of the substratum or surface and the overmolding material. The surface could be glass, metal, or another surface. The over molding materials majorly used are thermoplastics and rubber. During overmolding, the activity that happens is either mechanical or chemical which leaves the two substances bonded.
Two plastic materials are not necessarily injection molding machines in the same injection molding two times; products from a mold out of the mold, and then placed in another set of molds. The second injection molding. Therefore, the general molding process is usually completed by two sets of molds, without the need for a dedicated Bicolor injection molding machine.
Two-color mold and over-mold Overview:
Plastic mold in the design should pay attention to the positioning of the hard plastic pieces, and shrink, to prevent plastic deformation. Two-color mold is increasingly prevalent in the market, in this process can make the appearance of the product more beautiful, easy For color and can not spray, but expensive, high technical requirements.
1, Regarding the mold aspect difference
1，Cavity’s two shapes are different, respectively, forming a product. The Core’s two shapes are exactly the same.
2. Die cavity, core to the center of rotation 180o, must match. The design must do this check action.
3. Note thimble hole location, the minimum distance 210mm. Large mold to be appropriate to increase the number of top hole sticks. And, because the thimble attached to the injection molding machine itself is not long enough, we must design an extension thimble in our mold. The thimble should grow about 150mm around the mold base. Rear mold base plate must be designed 2 locating ring
4.cavity panel plus the total thickness of the A plate can not be less than 170mm. Look carefully at the other reference data for this type of injection molding machine. For example, the maximum Die thickness, the minimum die thickness, the distance to the top stick hole, and more.
5. Three board mold outlet can best be designed to automatically release action. Special attention should be paid to the release of soft glue outlet action is possible.
2, Regarding the injection molding aspect difference
1，The depth of the front sprue, not more than 65mm. The distance from the top of the sprue on the upper side (large spout) to the center of the mold embryo is not less than 150mm.
2. In the design of the second injection of the cavity, in order to avoid cavity scratches the first good product glue bits, you can design part of the avoidance. However, we must carefully consider the strength of each sealing plastic position, that is: in the injection molding, whether there will be a large injection pressure, the plastic deformation, resulting in the second injection may have approved the production possible?
3.The first injection molding product size can be slightly larger, so that it can be pressed in the second cavity with another tight, in order to achieve the role of plastic closures.
4. Note that in the second injection, the plastic flow will rush to the first good product that has been formed, the plastic deformation? If this is possible, we must find ways to improve.