1. The basic principle of dual color mode design:
Hard rubber 1 times, soft rubber 2 times;
Transparent 1 time, non-transparent 2 times;
High temperature molding plastics are used for 1 time, and molding temperature is low for 2 times;
The above is the basic principle of doing two-color molds, otherwise the mold will be made white; in addition, when using plastic seals, it is necessary to rely on breaking the sealant instead of inserting the sealant. Even if it is suggested that customers modify the product, they must try to rely on broken sealant;
2. The guide bushes of the mold blank guide must be symmetric about up and down, symmetrical around the front and rear molds.
3. The rear mold must rotate 180 degrees, the front mold does not move.
4. The distance between the products must be based on the distance between the nozzles of the injection molding machine. Some foreign two-color injection molding machines have adjustable gun nozzle spacing, some are not adjustable, and domestic ones are not adjustable.
5. Two independent ejector systems, the top stick is also two. The rear mold and the two products are the same, the ejector pins are all the same, and they are in a rotational relationship. Do not make a translational relationship.
6. The ejector plate can only be reset with a spring. It cannot be forced to reset with a screw because the rear mold is to be rotated.
7. The edge locks must be on the four sides of the center of the mold, and the front and rear molds must be symmetrical. Otherwise, the back molds will not align with the front molds when they are rotated 180 degrees.
8. If the distance between the glue-in point and the distance between the nozzles of the injection molding machine is different, the top-bar hole should be made into a waist shape because the distance between the top-screws of the injection molding machine is not adjustable. Note that most of the injection-molded nozzles of the domestic two-color injection molding machine are not adjustable.
9. Pay attention to the direction of the parallel nozzle of the injection molding machine provided by the customer, which is the X axis or Y axis, to determine the layout of the product rank.
10. The direction of transporting water into and out of water must be on the side of the heavens and the earth, and every circulating water must enter and exit on the same surface. It is not allowed to enter the water in the sky, and the water is on the ground. Since the rear mold should be rotated 180 degrees, pay attention to the mold The size can't exceed the height of the injection molding machine out of the sink, otherwise it can't pick up the water.
11. The first injection molded product should be placed on the non-operating side, because the product should be rotated 180 degrees for the second injection after the first injection, just to the operating side, to facilitate the product.
12. The die position of the exit die must be on the operating side and the non-operating side, not on the side of the heavens and earths, because their products must be fully automatic.
13. Note on the parting surface: The parting surface of the back mold parting surface should be the back mold after the merger of the two products; the front mold parting surface should be taken from a single product, and the combined products cannot be taken. Parting surface.
14. The tolerance of the front and rear flanges is negative 0.05mm, the tolerance between the two flanges is plus or minus 0.02mm, the gap between the top stick and the top stick holes is 0.1mm, and the center-to-center tolerance of the front and rear mold guide columns is positive and negative. 0.01, the tolerances of the four sides and the depth of the frame must be added. Otherwise, when the rear mold rotates by 180 degrees, a batch front will be generated due to inconsistent height. The box depth tolerance is negative 0.02mm.
15. If the mold blank has been machined in the die blank factory, when the factory wants to process the pick mouth and the top bar hole, take the center of the distance between the four guide pin bushing holes as the reference, otherwise the deviation will be too much, easy to card. Die. When specifying the die, it should be noted that it is a two-color die, the four guide pillars and the frame are symmetrical, and the back die can be matched with the front die after rotating 180 degrees.
16. If it is the two-color words of the rear mold rotation, it is much simpler. Like the two front mold cores, one side is injection-molded with hard glue, and the other is rotated 180 degrees (note that the product can not be dropped when turning, the gate can be automatically separated). After the injection of soft glue on the other side, the injection hard plastic does not need to be equipped with a thimble. It is only necessary to arrange it on the soft side of the mold core. In addition, it should be noted that if the soft glue is completely entangled with the hard rubber, then only hard glue is needed. Shrinkage, if the contour is in contact with hard plastic soft glue should shrink.
17. If it is a two-color mold of a mold, then it is a straight barrel, a 90-degree barrel shot, no rotation, only a core, the separation method of soft and hard plastic by seal glue.
18. Cavity two outer shape is different, each forming one kind of product. Core profile and two of the same intact.
19. Before the mold, after the mold is rotated 180° in the center, it must match. This inspection must be done during design.
20. Pay attention to the position of the thimble hole. The minimum distance is 210mm. The large mold must increase the number of the top hole properly. Also, because the thimble attached to the injection molding machine itself is not long enough, we must design an extended thimble in our mold. Mold base plate about 150mm.
21. Two positioning rings must be designed on the rear mold base plate.
The total thickness of the panel plus the front mold 22. A plate of not less than 170mm. Carefully view the other reference data of the injection molding machine of this type, for example, the maximum capacity of the mold thickness, the minimum thickness of the receiving mold, ejector pin and hole pitch and the like.
23. The depth of the front side SPRUE should not exceed 65mm. The interval from the top of the SPRUE on the upper side (big nozzle) to the center of the mold blank should not be less than 150mm.
24. When designing the second injection of CAVITY, in order to prevent CAVITY from inserting (or rubbing) the gel of the product that has been molded for the first time, it is possible to design a partial avoidance. However, it is necessary to carefully consider the position of each sealant. Intensity, that is: In the injection molding, whether there will be plastic deformation under large injection pressure, which may lead to the possibility that the second injection may generate a batch front;
25. When injection molding, the size of the first injection molded product may be slightly larger so that it can be tightly pressed with another CAVITY during the second molding to achieve the effect of the sealant.
26. Before closing the A and B boards, please pay attention to whether the front mold Slider or Lifter will reset and crush the product. In this case, it is necessary to think of ways to close the boards A and B before the SLIDER or LIFET of the front mold. Talent reset.
27. Both CAVITY and CORE's water delivery arrangements are as full and balanced as possible.
28. In 99% of the cases, the hard plastic part of the first injection molded product is partially injected, and the soft plastic part of the injection molded product is partially. Since the soft plastic is easily deformed.
29. Note that during the second injection molding, will the movement of the plastic material impervious to the first product that has been molded to deform the gel position? Assuming this is possible, we must improve the method.
30. Two-color mold must be careful to choose the location of the gate. One product is best to choose submerged entry, so that the product and the flow channel can be automatically cut off. When the submerged entry can not be used, three-plate mold or hot runner mold can be considered. If the material is a point gate, it should be waved to avoid touching the secondary material due to a residue at the point of entry.
31. Two-shot injection molds often use rotary injection molds. The punch/recess molds at two positions of the rotary injection mold require the same size and accuracy, and are well-matched with the mold/bump. When the two-color injection molding machine cannot be used for ejection When the ejection mechanism is released, a hydraulic ejector ejection mechanism must be provided on the turntable.
32. Two-color mold injection molding usually uses the same plastic with different colors, or it can be two different plastic materials. This time we must consider the interface of the two materials, the difference in shrinkage, processing parameters and other aspects.
Two-color injection molding products are generally based on hard plastics such as ABS and PC, and TPE soft plastics. Due to cost or application, full consideration may be given to the lack of good adhesion and fusion between the two materials. There is a lot of problems such as the mold processing at the joints (generally, the phenomenon of embossing or the need for mold sealing grooves) and the thickness of the material.
In order to make the two types of plastics more 'sticky', consider the 'stickiness' between the materials and the roughness of the mold surface. The two-color injection molding has a special TPU material; the smoother the appearance of the mold, the tighter the 'tackiness' of the mold.
33. In general, the shrinkage of two-color molds depends on the primary material. Because the primary material already holds the contour of the plastic product, the secondary material does not shrink more. As to how to determine the primary and secondary materials, there are Many factors to consider, such as raw material flow, plastic shapes, etc.
34. Pay attention to the positioning of the front and rear molds; insert all through, and make the slope of the broken surface fall as large as possible, with 0.1 mm or more.
35. For ABS/PC, ABS/PC ABS, and ABS/PMMA two-color injection molding, it is necessary to inject a PC with a higher temperature, PC ABS, or PMMA. If it is a transparent surface mold, most of them use a flip-mold structure.
36. Transparent large two-color injection molding is a point of attention for structural design:
The reservation of the gate location must be agreed in advance with the mold factory;
The material thickness is recommended to use transparent 0.8mm or more, non-transparent 0.7mm or more, non-transparent light color as much as possible, pay attention to light when there are LED lights;
The transparent part has the same width of the parting surface and the hole, and the width is recommended to be 0.5mm. The curved surface is smooth, avoiding the side view, can penetrate far, unsightly, and minimize the hole;
The thickness of non-transparent parts is limited, and the upper ribs and other structures should be between 0.5-0.6mm as much as possible to avoid shrinkage;
At present, it is not recommended to use two-color injection molding with a main lens. The cost of molds and products is too high. There are considerable requirements for the equipment manufacturers and technical level of the mold manufacturers. If they do, they need to provide a detailed solution for the entire process. For the intermediate links, they need to be reviewed;
For large-area two-color injection molded parts, the two key tests are drop and cold and thermal shock. In both tests, transparent and non-transparent parts are easily released. Hot and cold shocks -40-65, time 48 hours.
The structure of the two-color parts is simplified as much as possible, and the complex parts are made above the fitting parts. The width of the ribs of the non-transparent parts should be 0.5-0.6mm as far as possible to avoid shrinkage.