Most designer are focus on one color plastic injection mold, so they don’t to how to design when we met two color plastic injection mold.so we will talk about the theory and important point about two color mold.two color mold have another name “two shot mold”,they inject two resin on same machine but injection two times, typically consist of 2 sets of mold,the core side will rotate 180 degree,but cavity side will be fixed.but the molding part are only ejected out one time.we aways call it two color injection molding and need special two color injection machine.
The characteristics of two color mould:
1, two shape of cavity is different, forming 1 kinds of products each. But core side hve same shape. (Note: if there is not the same,use sliders)
2, after the cavity rotate 180 degree,the cavity must fit another core, Designer should pay attention to this point.
3, please carefully check the data of color injection molding machine such as, maximum mold thickness, the minimum allowable mold thickness, K.O. holes distance etc..
4, gate should be cutted automatically in 3 plate two color mold,especially soft resin.
5,when we design the second injection cavity,we should leave some space to avoid scratch,but must think about the seal area,the molding part have the possibility of deformation and cause flash
6, we can make the first molding part a little bit bigger than spec.it will be pressed tighter when second injection,reduce the risk of flash.
7, pay attention to in second injection molding, if they will make the first molding part deformed by resin flow,If that is possible, we must think of a way to improve the.
8, we should make the cooling system plenty,balance and same in two mold
9, 99% we injection hard material first ,before soft is easy to deform
10, in order to make the two plastic stick more tightly, we should consider “sticky” of two resin and the roughness of mold surface