How to shorten the injection cycle?

I. Optimization of Injection Molding Process Parameters

1. Injection Speed: The injection speed is crucial for the filling efficiency and product quality. Appropriately increasing the injection speed can shorten the filling time, especially for thin-walled products. However, an excessively high injection speed can lead to problems such as air entrapment and flash. The optimal injection speed should be determined through multiple trial moldings based on the product structure, wall thickness, and raw material properties.

2. Holding Pressure Time and Pressure: The holding pressure phase is used to compensate for the shrinkage of the plastic during cooling and ensure the dimensional accuracy of the product. However, an overly long holding pressure time will extend the injection molding cycle and cause demolding difficulties, while an excessively high holding pressure will generate internal stress in the product, leading to warping and deformation. The holding pressure time and pressure should be reasonably reduced according to the specific situation of the product through analysis and testing.

3. Cooling Time: The cooling time accounts for a large proportion of the injection molding cycle, so optimizing the cooling process is essential. Improving the cooling water channel design of the mold, such as increasing the diameter of the water channel and optimizing the layout, can enhance the cooling efficiency and shorten the cooling time. Selecting high-efficiency cooling media, such as special cooling oils, can also promote the rapid cooling of the plastic.

4. Enhancement of Plasticizing Capacity: When the plasticizing capacity is insufficient, methods such as using a barrier screw, a large-diameter screw, increasing the screw groove depth, increasing the screw rotation speed (except for some shear-sensitive plastics), reducing the back pressure, adopting a hydraulic nozzle seal, pre-plasticizer design, and a holding pressure device can be used to enhance the plasticizing capacity.

   
   

   

II. Mold Design and Improvement

1. Optimization of the Runner System: Shortening the length of the main runner and sub-runner, reasonably reducing the diameter of the runner, and polishing the runner surface can reduce the pressure loss and heat dissipation of the melt, and shorten the flow time. Hot runner molds can avoid the waste of cooling time in cold runner molds, reduce the injection and feeding time, shorten the mold opening stroke, and facilitate the removal of products in multi-cavity injection molding, thus shortening the cycle.

2. Gate Design: The selection of the appropriate gate type and size has a significant impact on the injection molding cycle. For example, the pin point gate has advantages such as fast melt flow speed and small gate marks. The gate size should be determined according to the product shape, size, and raw material properties to ensure smooth melt filling and avoid problems such as difficult filling or excessive cooling time.

3. Perfection of the Demolding Mechanism: The demolding mechanism affects the demolding time. Using a reasonable ejection method, such as direct ejection or special demolding structures like inclined ejectors and sliders for products with complex shapes, and selecting the appropriate ejection points can ensure smooth demolding and reduce time waste.

III. Upgrading and Maintenance of Injection Molding Equipment

1. Selection of High-performance Injection Molding Machines: High-performance injection molding machines have high injection pressure, fast mold opening and closing speed, and precise control systems, which can ensure the efficient and stable operation of the injection molding process and shorten the injection molding cycle.

2. Equipment Maintenance: Regular maintenance of the injection molding machine, including repairing or replacing the worn screw, checking the oil quality, quantity, and sealing performance of the hydraulic system, and detecting and maintaining the electrical control system, can ensure the stable performance of the equipment and reduce the cycle extension caused by equipment failures or performance degradation.

IV. Selection and Treatment of Raw Materials

1. Selection of Suitable Plastic Raw Materials: Different plastic raw materials have different properties that affect the injection molding cycle. Raw materials with high melt flow rate can fill the mold cavity quickly, and those with fast crystallization speed can cool down rapidly. The appropriate raw materials should be selected according to the product requirements.

2. Drying and Preheating of Raw Materials: Hygroscopic raw materials such as nylon need to be dried thoroughly to ensure smooth melt flow. Preheating high-viscosity or temperature-sensitive raw materials can reduce their viscosity and improve the plasticizing efficiency, accelerating the injection molding process.

V. Application of Automation in Production

1. Introduction of Automated Part Removal Devices: Manual part removal has unstable operation time, which affects the continuity of production. Automated part removal devices can remove products accurately and timely according to the preset program, shortening the cycle and improving production efficiency.

2. Implementation of Full-process Automated Monitoring and Control: Installing sensors at key positions to monitor injection molding parameters in real-time, and using an automated control system to adjust deviations automatically can reduce the time consumption of manual intervention and ensure the efficient and stable operation of the injection molding process, shortening the injection molding cycle.