Precautions for injection mold design
1. The ejector should be even and strong, easy to replace and repair.
2. The mold core and cavity should have sufficient rigidity and strength.
3. The mold should be hardened, polished, and wear-resistant steel should be selected, and the easily worn parts should be easy to repair and replace.
4. The mold should be equipped with an exhaust overflow groove, and it should be located at a location prone to weld marks.
5. The cross section of the pouring system should be large, and the flow should be straight and short to facilitate uniform fiber dispersion.
6. The shape and wall thickness of the plastic parts should be specially considered to facilitate the smooth flow of the material to fill the cavity, and try to avoid sharp corners and gaps.
7. The demoulding angle should be large, 1°～2° for 15% glass fiber, 2°～3° for 30% glass fiber. When the demolding slope is not allowed, forced demolding should be avoided, and a horizontal parting structure should be adopted.
8. The design of the feed inlet should consider preventing insufficient filling, anisotropic deformation, uneven distribution of glass fibers, and easy to produce weld marks and other undesirable consequences. The feed port should be flakes, wide and thin, fan-shaped, ring-shaped and multi-point feed ports to make the material flow turbulent, and the glass fiber is evenly dispersed to reduce anisotropy. It is best not to use needle-shaped feed ports. The cross section of the mouth can be increased appropriately, and its length should be short.
Setting of injection mold temperature
1. Mold temperature affects the molding cycle and molding quality. In actual operation, it is set from the lowest appropriate mold temperature of the material used, and then adjusted to a higher level according to the quality condition.
2. Correctly speaking, the mold temperature refers to the temperature of the cavity surface when the molding is performed. In the mold design and the condition setting of the molding engineering, it is important not only to maintain a proper temperature, but also to make it uniform. distributed.
3. Uneven mold temperature distribution will lead to uneven shrinkage and internal stress, which makes the molding mouth easy to deform and warp.
4. Increase the mold temperature to obtain the following effects:
(1) Increase the crystallinity of the molded product and a more uniform structure;
(2) Make the molding shrinkage more fully and reduce the post-shrinkage;
(3) Improve the strength and heat resistance of molded products;
(4) Reduce internal stress residue, molecular alignment and deformation;
(5) Reduce the flow resistance during filling and reduce the pressure loss;
(6) Make the appearance of the molded product more shiny;
(7) Increase the chance of flashing in molded products.