1.The model and series are determined by the product and plastic.
Since there are many types of injection molding machines, it is necessary to correctly determine which Injection Molding Machine or series the product should be produced from at the beginning, such as general thermoplastic or bakelite raw materials or PET raw materials. Color, two-color, multi-color, interlayer or mixed color, etc. In addition, some products require conditions such as high stability (closed loop), high precision, ultra-high firing rate, high shot pressure or rapid production (multi-loop), and the appropriate series must also be selected for production.
2. Determine whether the "Large Column Inner Distance", "Mold Thickness", "Minimum Mold Size" and "Die Plate Size" of the machine are appropriate from the mold size to confirm whether the mold can be placed.
◆ The width and height of the mold must be smaller than or at least one side smaller than the inner distance of the large column;
◆ The width and height of the mold should be within the size range of the mold plate;
◆ The thickness of the mold must be between the mold thickness of the injection molding machine;
◆ The width and height of the mold must meet the minimum mold size recommended by the injection molding machine, and it will not work if it is too small.
3. From the mold and the finished product, it is judged whether the "mold opening stroke" and "mold ejection stroke" are sufficient to take out the finished product.
◆ The mold opening stroke must be at least more than twice the height of the finished product in the direction of opening and closing the mold, and the length of the sprue must be included;
◆ The stripping stroke must be enough to eject the finished product.
4. The tonnage of "clamping force" is determined by the product and plastic.
When the raw materials are injected into the mold cavity at high pressure, a mold-supporting force is generated. Therefore, the clamping unit of the injection molding machine must provide enough "clamping force" to prevent the mold from being opened.
5. Determine the required "injection volume" from the weight of the finished product and the number of mold cavities and select the appropriate "screw diameter".
◆ Calculating the weight of the finished product needs to consider the number of mold cavities (a mold with several cavities);
◆ For the sake of stability, the injection volume must be more than 1.35 times the weight of the finished product, that is, the weight of the finished product must be within 75% of the injection volume.
6. The conditions of "screw compression ratio" and "injection pressure" are judged by the plastic.
Some engineering plastics require higher injection pressure and appropriate screw compression ratio design to have better molding effects. Therefore, in order to make the finished product shot better, the needs of injection pressure and compression ratio should also be considered when selecting the screw. . Generally speaking, a screw with a smaller diameter can provide a higher injection pressure.
7. Confirmation of "Injection Speed".
Some finished products require high injection rate and rapid injection for stable molding, such as ultra-thin finished products. In this case, it may be necessary to confirm whether the injection rate and rate of injection of the machine are sufficient, and whether it needs to be equipped with pressure accumulators, closed-loop control and other devices. Generally speaking, under the same conditions, a screw that can provide a higher injection pressure usually has a lower shot speed, on the contrary, a screw that can provide a lower injection pressure usually has a higher shot speed. Therefore, when selecting the screw diameter, the injection volume, injection pressure and injection rate (injection speed) need to be cross-considered and selected.
