I have to collect the experience of two-color mold design and two-color mold injection molding that the 36 two-color mold experts have collected!
1 hard rubber, soft 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 mold, otherwise the mold will be done in white; In addition, the sealant should be used to break the sealant as far as possible, without inserting the sealant, even if it is suggested that the customer to modify the product must also try to rely on broken sealant;
2. The guide bushes of the mold blank guide must be symmetrical about the top and bottom and the front and rear molds.
3. The rear mold is rotated 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. The distance between the nozzles of some foreign two-color injection molding machines is adjustable, and some are not adjustable. The domestic ones are not adjustable.
5. Two independent ejector systems, top two. The rear mold and the two products are the same, the ejectors are all the same, and they are in a rotational relationship. It must not be made into 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 lock must be on the four sides of the center of the mold, and the front and back molds are symmetrical. Otherwise, the back mold will not align with the front mold when it rotates 180 degrees.
8. If the distance between the infeed 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 spacing between the top bar of the injection molding machine is not adjustable. Note that most injection moulding nozzles for domestic two-color injection molding machines 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, in order to determine the layout of the product.
10. The direction of transporting water into and out of water must be on the side of the heavens and the earth, and each circulating water must enter and exit on the same surface. It is not allowed to enter the water in the day, and the water is on the ground. Since the rear mold should rotate 180 degrees, pay attention to the mold The size must not exceed the height of the injection molding machine outfall, otherwise the water cannot be picked up.
11. The first injection molded product should be placed on the non-operating side because the product is 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 should be on the operating side and the non-operating side. It should not be on the side of the heavens and the earth because their products should be fully automatic.
13. Note on the parting surface: The parting surface of the back mold parting surface shall be the back mold after the merger of the two products; the front mold parting surface shall be taken from a single product, and the merged product may not 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 tolerances of the front and rear mold guide pillars are positive and negative. 0.01, the four sides and depth of the frame must be tolerances, otherwise, when the rear mold rotates by 180 degrees, the front edge will be generated due to inconsistent height. The box depth tolerance is negative 0.02mm.
15. If the mold blank has been processed at the die blank factory, we must take the center of the distance between the four guide pillar guide holes as the reference when processing the nozzles and top stick holes. Die. When ordering the mold, it should be noted that it is a two-color mold blank, and the guide bushes and frames of the four guide pillars are symmetrical, and the rear mold can be matched with the front mold 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. The shrinkage, if the contour is in contact with hard rubber 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, does not need to rotate, just a core, the separation method of soft and hard plastic by positioning seal glue.
18. The two shapes of Cavity are different and one type of product is formed separately. The Core's two shapes are the same.
19. The front and rear molds of the mold must be matched after they are rotated 180° in the center. This check must be done at design time.
20. Pay attention to the position of the thimble hole. The minimum interval is 210mm. Large molds must be properly increased in the number of top bar holes. In addition, because the ejector attached to the injection molding machine itself is not long enough, it is necessary to design an extended ejector pin in our mold, and the ejector pin should be about 150 mm long from the bottom of the mold base.
21. Two positioning rings must be designed on the rear mold base plate.
22. The total thickness of the front mold panel plus the 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 film thickness, the minimum mold film thickness, the top hole spacing and so on.
23. The depth of the front SPRUE should not exceed 65mm. The distance from the top of the SPRUE on the upper side (large nozzle) to the center of the mold blank is not less than 150mm.
24. When designing the second injection of CAVITY, in order to prevent CAVITY from inserting (or wiping) the first time a good product gel was formed, a partial avoidance can be designed. However, it is necessary to think carefully about the strength of each sealant position. That is: in the injection molding, whether there will be plastic deformation under the large injection pressure, which may lead to the possibility that the second injection may have a batch front;
25. When injection molding, the size of the first injection molded product may be slightly larger so that it can be pressed tighter with another CAVITY during the second molding to achieve the sealant effect.
26. Before closing the A and B plates, should you pay attention to whether the front mold Slider or Lifter can be reset and crush the product? In this way, it is necessary to think of ways to make the A and B boards to be closed before the SLIDER or LIFET of the front die can be reset.
27. Both CAVITY and CORE's water delivery arrangements are as full as possible and balanced.
28. In 99% of the cases, the hard plastic part of the first injection molded product was partially injected, and the soft plastic part of the injection molded product was partially applied. Due to the flexible plastic deformation.
29. Pay attention to whether the movement of plastics will drive the product that has been molded for the first time in the second injection molding to deform the glue position? Assuming this is possible, it must be improved.
30. Two-color molds must be carefully selected gate position. It is best to choose a submerged type of rubber for a product so that the product and the flow channel can be cut off automatically. When submerged entry is not possible, triple plate or hot runner molds may be considered. If the material is a spot gate, it should be waved to avoid touching the secondary material due to a residue at the point of entry.
31. Two-color injection molds often use rotary injection molds. The male/female dies in two positions of the rotary injection mold require uniform dimensions and accuracy, and are well matched with the female/male dies. When it is not possible to use the ejector ejection mechanism on a two-color injection molding machine, a hydraulic ejector ejection mechanism must be provided on the rotary table.
32. Two-color mold injection molding usually use the same plastic of different colors, it can also 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 should be given to the lack of good adhesion and fusion between the two materials used. 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 two plastics "tight" tighter, consider the "stickiness" between the materials and the roughness of the mold's appearance. Two-color injection molding has special TPU material; the smoother the appearance of the mold, the tighter they become.
33. In general, the shrinkage of a two-color mold depends on the primary material. Because the primary material already holds the contour of the plastic, the secondary material does not shrink more. As for how to determine primary and secondary materials, there are many factors to be considered, such as the fluidity of raw materials, the shape of plastic products, and so on.
34. Pay attention to the positioning of the front and rear molds; all the penetrations and the slope of the broken surface should be as large as possible, and 0.1 mm or more.
35. When ABS/PC, ABS/PC ABS, ABS/PMMA two-color injection molding, it is necessary to inject the PC with higher temperature, PC ABS or PMMA. If it is a transparent shell mold, most of the 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 as the parting surface and the hole, and the width is recommended to be 0.5mm. The curved surface is smooth, avoiding the side view, and can penetrate very far, unsightly, minimize the hole;
The thickness of non-transparent parts is limited, and the upper ribs and other structures are 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 done, the other party needs to provide a detailed solution for the entire process for evaluation. , for the middle part of the need to review;
For large-area two-color injection molded parts, the two key tests are drop and hot and cold shocks. In both tests, transparent and non-transparent parts are easily released. Hot and cold shock -40-65, time 48 hours.
The structure of the two-color components is simplified as much as possible, and the complex components are made above. The width of the ribs of the non-transparent components is as large as 0.5-0.6 mm to avoid shrinkage.
Yuzhuo Precision Co., Ltd. provides professional one-stop service for designing, manufacturing,
injection molding, painting, screen printing and assembly of precision plastic two-color molds. It is located in the Pearl River Delta, Guangdong, Hong Kong and Macau, Dawan District, with developed transportation, air and shipping facilities, and fast logistics. For more details on ODM/OEM processing customization, please call the hotline: 400-8167-528, or click on the online customer service website to inquire. We are very happy to serve you.
