1. Barrel temperature, mold temperature

The screw barrel temperature is set according to the properties of different plastic materials. The barrel setting temperature is generally 10°C-30°C higher than the melting point of the plastic. It must be noted that materials provided by different manufacturers will have different melting points and allowable residence times in the barrel due to different synthesis methods or types of additives added.

Circulating water cooling is generally used when setting the mold temperature. However, when producing products with precise dimensions or high surface quality requirements, a mold temperature machine that can be accurately controlled should be used according to process requirements.

2. Injection holding time and cooling time

Injection time, holding pressure time and cooling time must be set according to product thickness, mold temperature, material properties, etc. The injection time is generally set to be slightly longer than the time for the screw to complete the injection stroke. Too long an injection time will not only cause negative effects such as mechanical wear and increased energy consumption, but will also prolong the molding cycle. The holding time is set according to the thickness of the product. Thin-walled products do not need holding time when molding. When setting the holding time, as long as there is no obvious depression on the surface of the product, it can also be determined by the weighing method, gradually The optimal holding time can be determined by extending the holding time until the product quality no longer changes. The cooling time also needs to be determined based on product thickness, mold temperature, and material properties. Generally, amorphous polymers require longer cooling times than crystalline polymers.

3. Injection pressure and speed

The injection pressure setting should follow the principle of low rather than high, as long as it can provide enough power to achieve the required injection speed so that the melt can smoothly fill the cavity. Excessive pressure can easily cause internal stress in the product; but in When molding products with high dimensional accuracy, in order to prevent excessive shrinkage of the product, high-pressure injection can be used to reduce the shrinkage of the product after demoulding.

The injection speed will affect the appearance quality of the product, and its settings should be set according to the geometric structure of the mold, exhaust conditions, etc. Generally, on the premise of ensuring a good appearance, the injection speed should be increased as much as possible to reduce the filling time. In injection molding, when the melt flows in the mold, a solidified layer will be formed on the mold wall, thus reducing the thickness of the flowable channel. Generally, depending on the mold structure and injection speed, the mold wall will have a solidified layer of about 0.2mm. Therefore, faster injection speeds are usually used in molding.

4. Nylon cable tie injection molding requirements:

Product quality requirements: The product meets the specified tensile strength standards; there are no silver wires, bubbles, sink marks and other undesirable phenomena on the surface; after molding, the product has good tightness and no looseness. The material used is PA66; the injection molding machine is JSW1000-EⅡ-SP, the mold structure is hot runner type, and the gate type is point gate.

First, determine the process parameter setting principles based on product characteristics and mold structure: (1) Because the product flow length is long and L/t (process to wall thickness ratio) is 511, high-speed injection molding should be selected; (2) Gate type For point gates, higher pressure must be used to overcome the resistance during flow; (3) In order to ensure that the product can be filled smoothly, the melt must have good fluidity, and the molding temperature should be appropriately high; (4) High-pressure and high-speed injection It is easy to produce flash at the end, so the molding machine must have low inertia pressure and speed switching; (5) Because the product wall thickness is small, pressure holding is not required. Related parameters: barrel temperature: 310-335C°, nozzle temperature 290-310C°, hot runner temperature 290-310C°, mold temperature: 80C°, first-level injection (pressure, speed, stroke) %, mm80, 95, 60