Attention must be paid to in the design of two-color mold

1. Basic principles of two-color injection mold design:

(1) Make hard glue once and soft glue twice;

(2) Transparent once, non transparent twice;

2K MOLD-TWO SHOT INJECTION MOLDS

(3) The plastic with high injection molding temperature shall be made once, and the plastic with low molding temperature shall be made twice;

2. The guide pillar and guide sleeve of the mold must be symmetrical from top to bottom, from left to right, and from front to back.

3. The rear die shall rotate 180 degrees, and the front die shall not move.

4. The product spacing must be based on the nozzle spacing of the injection molding machine. The nozzle spacing of some two-color injection molding machines abroad is adjustable, some are not adjustable, and domestic ones are not adjustable.

5. There are two independent ejection systems, including two jacking rods. The two products of the rear mold are the same, and the thimble is the same. It is a rotation relationship. It must not be a translation relationship.

6. The thimble plate can only be reset with spring, and cannot be forced to reset with screws, because the rear die needs to rotate.

7. The side lock must be on the four sides of the mold center, and the front and rear molds must be symmetrical. Otherwise, when the rear mold rotates 180 degrees, it will not align with the front mold.

8. If the distance between the glue feeding points and the injection molding machine nozzle is different, the ejector pin hole should be waist shaped, because the ejector pin distance of the injection molding machine is not adjustable. Note: Most injection nozzles of domestic two-color injection molding machines cannot be adjusted.

9. Note that the injection molding machine provided by the customer is parallel to the nozzle direction, which is the X axis or Y axis, so as to determine the product layout.

10. The water inlet and outlet direction must be at the heaven and earth side, and each circulating water inlet and outlet must be on the same side. Water inlet and outlet must not be at the heaven side, and water outlet must be at the earth side. Because the rear mold needs to rotate 180 degrees, it should be noted that the size of the mold should not exceed the height of the water outlet tank of the injection molding machine, otherwise, water cannot be transported.

11. The products for the first injection should be placed on the non operating side, because after the first injection, the products should be rotated 180 degrees for the second injection, just turn to the operating side, so that the products can be easily taken.

12. The coding position of the outlet die should be at the operation side and non operation side, not at the heaven and earth side, because their products should be fully automatic.

13. Precautions for parting surface: the parting surface of the rear mold shall be the one obtained after merging the two products; The parting surface of the front die should be a single product, not a combined product parting surface.

14. The tolerance of the front and rear flanges is minus 0.05mm, the tolerance of the distance between the two flanges is plus or minus 0.02mm, the clearance between the ejector pin and the ejector pin hole is 0.1mm on one side, the tolerance of the center distance between the guide posts of the front and rear mold sleeves is plus or minus 0.01, and the tolerance of the four sides and the depth of the mold frame shall be added, otherwise, when the rear mold rotates 180 degrees, the front edge will be generated due to the inconsistent height; The tolerance of frame depth is minus 0.02mm.

15. If the mold has been processed in the mold factory, the distance center of the four guide pillar guide sleeve holes shall be taken as the benchmark when the factory needs to process the jack and ejector pin holes, otherwise the deviation is too much and the mold is easy to be stuck. When fixing the mold embryo, it should be noted that it is a two-color mold embryo, the four guide posts and guide sleeves are symmetrical with the frame, and the rear mold can match the front mold after rotating 180 degrees.

16. If it is a set of two-color molds, it is a straight barrel and a 90 degree barrel for glue injection. It does not need to rotate, but only needs a mold core. The separation method of soft glue and hard glue depends on line sealing.

17. The two profiles of the cavity are different, forming a product separately, while the two profiles of the core are intact.

18. The front and back dies of the die must be aligned after rotating 180 ° in the center. This check action is required during design.

19. Pay attention to the position of the ejector pin hole, with a minimum interval of 210mm. For large molds, the number of ejector pin holes must be appropriately increased. Because the ejector pin attached to the injection molding machine is not long enough, we must design an extended ejector pin in our mold, which is about 150 mm longer than the mold base plate.

20. Two locating rings must be designed on the back mold base plate.

21. The total thickness of front formwork panel plus A plate shall not be less than 170mm. Please carefully check other reference data of this type of injection molding machine, such as the maximum mold holding thickness, the minimum mold holding thickness, and the spacing of ejector pin holes.

22. The depth of front SPRUE shall not exceed 65mm. The distance from the top of SPRUE on the upper side (big water outlet) to the center of the mold shall not be less than 150mm.

23. When designing the cavity for the second injection molding, in order to prevent the cavity from inserting (or scratching) the rubber position of the first molded product, a part can be designed to avoid void.

24. During injection molding, the product size of the first injection molding can be slightly larger, so that it can be pressed more tightly with another cavity during the second molding to achieve the role of sealant.

25. The water delivery arrangement of the two cavities and cores shall be as sufficient as possible, balanced and the same.

26. The gate position of two-color injection mold must be carefully selected. It is better to select the latent glue feeding for the primary product, so that the product and flow channel can be automatically cut off. When the latent glue feeding cannot be used, three plate mold or hot runner mold can be considered. If the primary material is a point gate, it shall be waved to avoid the secondary material being penetrated due to the residue of the primary feeding point.

27. The two-color injection mold often adopts the rotary injection mold. The punch/die on the two positions of the rotary injection mold shall be consistent in size and accuracy, and shall fit well with the die/punch. When the ejection and demoulding mechanism on the two-color injection molding machine cannot be used, the hydraulic ejection and demoulding mechanism must be set on the rotary table.

28. Two color injection mold usually uses the same plastic with different colors or two different plastic raw materials for injection molding. At this time, it is necessary to consider the interface effect, shrinkage difference, processing parameters and other aspects of the two materials.

29. Generally speaking, the shrinkage of two-color die depends on the primary material. Because the primary material has supported the contour of the plastic product, the secondary material will not shrink more. As for how to determine the primary and secondary materials, there are many factors to be considered, such as the fluidity of raw materials, the shape of plastic products, etc.

30. Pay attention to the positioning of the front and rear molds, and try to make the slope drop of all penetrations and broken surfaces larger than 0.1mm.