Injection molding is the process of heating and melting thermoplastic or thermosetting plastics using a plastic molding machine (injection molding machine), injecting the molten plastic into a pre designed closed mold cavity under high pressure, cooling (thermoplastic) or curing (thermosetting plastic) to form, and then opening the mold to take out the product.

The injection molding process can achieve automated operation, with a short molding cycle. Generally, it only takes a few tens of seconds to a few minutes to complete a molding process, enabling large-scale mass production, improving production efficiency, and reducing production costs. It can ensure that the product has high dimensional accuracy and stability, with small dimensional deviations and good surface quality after molding, and can meet the requirements of various high-precision products.

Common defects and solutions in the injection molding process in Dalian

Common defects in the injection molding process include appearance defects, dimensional accuracy defects, and performance defects. The following are some common defects and their solutions:

Appearance defect

Material shortage

Reason: Insufficient plastic fluidity, insufficient injection pressure, unreasonable design of mold pouring system, etc.

Solution: Increase the temperature of the material barrel and mold to improve plastic flowability, increase injection pressure and injection speed, optimize the mold pouring system, and expand the size of the sprue and runner.

Flash

Reasons: Insufficient clamping force, excessive mold clearance, high injection pressure, and poor plastic flowability.

Solution: Check and adjust the mold clamping device of the injection molding machine to ensure sufficient clamping force, repair the mold, reduce the gap, lower the injection pressure, adjust the plastic formula or process parameters, and reduce fluidity.

bubble

Reason: Insufficient plastic drying, excessive injection molding speed, poor mold exhaust, etc.

Solution: Fully dry the plastic raw materials, reduce the injection molding speed, improve the mold exhaust system, and increase exhaust slots or holes.

Dimensional accuracy defects

Dimensional instability

Reason: Fluctuations in injection molding process parameters, mold wear, unstable plastic shrinkage rate, etc.

Solution: Stabilize injection molding process parameters, regularly inspect and maintain molds, select plastic raw materials with stable shrinkage, optimize mold design, and increase mold rigidity and stability.

deformation

Reasons: uneven cooling, improper injection pressure and holding time, unreasonable product structure design, etc.

Solution: Optimize the mold cooling system to ensure even cooling of the product, adjust the injection pressure and holding time, improve the product structure design, add reinforcement ribs, and if necessary, perform annealing treatment to eliminate internal stress.

Performance defects

Insufficient strength

Reason: Poor quality of plastic raw materials, improper injection molding process leading to insufficient plasticization of plastics, defects in products, etc.

Solution: Select high-quality plastic raw materials, increase the temperature of the material barrel and screw speed to ensure full plasticization of the plastic, solve appearance defects such as bubbles and missing materials in the product, optimize mold design, and ensure uniform thickness of the product.

weld line

Reason: The fusion line formed when plastic melt meets in the mold is usually caused by multi gate design, poor plastic flowability, and low mold temperature.

Solution: Optimize the mold gate design, reduce the possibility of weld lines, improve plastic flowability, appropriately increase the barrel temperature and mold temperature, increase injection speed and pressure, and promote melt fusion.

Injection molding machine is the core equipment of injection molding, mainly composed of injection device, mold clamping device, hydraulic system, and electrical control system. The injection device is responsible for heating, melting, and injecting plastic into the mold; The mold clamping device is used to achieve the opening and closing action of the mold and provide sufficient locking force to prevent the mold from expanding during injection; The hydraulic system provides power for various actions of the injection molding machine; The electrical control system is used to control various process parameters and action sequences of the injection molding machine.

Utilizing artificial intelligence, sensor technology, and automation control to achieve intelligent monitoring and optimization of the injection molding process. By monitoring the temperature, pressure, and other parameters of plastic melt online, adjusting process parameters in real time, and improving the stability of molding quality. In the context of increasingly strict environmental requirements, injection molding technology is also developing towards green direction, including the use of biodegradable plastic raw materials, optimization of energy utilization, reduction of waste emissions, etc., to reduce the impact on the environment.