Injection molding machines are essential in the manufacture of plastic products. They mainly melt plastic materials by heating and injecting them into the desired mold cavity. However, since the quality and efficiency of the product largely depends on the efficiency of the injection molding machine, necessary adjustments must be made. This article explores the reasons and methods for adjusting injection molding machines in depth, aiming to help readers better understand and master this critical process.

The Necessity of Injection Molding Machine Adjustment

Ensuring Product Quality

The main purpose of adjusting the injection molding machine is to produce the best quality final product. Problems caused by improper machine adjustment include bubbles, shrinkage, warping and deformation. For example, too high injection pressure can cause uneven flow of the plastic melt in the mold, resulting in bubbles or voids, and too short cooling time may cause unstable internal structure, resulting in shrinkage or deformation.

By adjusting the machine’s parameters, these defects can be avoided to a certain extent. It can also ensure that the product’s dimensional accuracy and surface finish are also good, which is especially important for high-demand products such as medical devices and automotive parts.

Improving Production Efficiency

Another important reason for the need to adjust the injection molding machine is to improve production efficiency. Correctly adjusting the machine can shorten the production time, increase production speed, and thus increase productivity. This is especially important for large projects that require a large number of products of the same specifications. For example, adjusting the injection and holding time can reduce the time required for each molding cycle, and increasing the injection speed and mold opening and closing speed can also speed up productivity. In addition, the frequency of defects can be reduced, thereby reducing the loss of working time, reducing unit costs, and enhancing the company’s competitiveness.

Reducing Material Waste

If the machine is not adjusted properly, poor results can be caused by material waste. For example, the injection pressure may be too high, thus causing material to overflow from the mold, or an inappropriate cooling time can cause the product to be molded incorrectly, requiring rework. Adjusting the machine also helps reduce the amount of wasted material and reduces the expenses required for production. This is even more important if the material is expensive, as reducing every bit of waste not only saves money but also reduces environmental impact. In addition, optimizing process parameters to ensure consistent product quality can reduce waste due to product defects.

Extending Equipment Lifespan

Proper adjustment and maintenance can also help extend the service life of injection molding machines. Improper machine adjustment may cause increased wear and tear, which may shorten the service life of the equipment or increase the related repair and replacement costs. For example, too high injection pressure and speed will cause greater impact and wear on mechanical parts, and improper temperature settings will accelerate the aging of heating accessories and molds. Regular adjustment and optimization of machine parameters can reduce equipment failure rate and maintenance frequency, thereby extending equipment life and reducing operating costs.

Meeting Specific Production Needs

Different products and mold designs require different machine settings. Fine-tuning the injection molding machine helps to meet specific requirements that may be encountered in production, making production as diverse as possible. For example, the production of thin-walled products requires higher injection speeds and pressures, while thick-walled products require longer holding and cooling times. Flexible adjustment of machine parameters can meet various product requirements, thus helping to improve the competitiveness of production in the market.

Key Parameters for Injection Molding Machine Adjustment

Temperature Adjustment

Temperature is an important factor in injection molding industry. Different types of plastics have different melt temperature. When the mold temperature does not match the plastic material, the molding quality is not ideal. Temperature control includes barrel temperature, nozzle temperature, and mold temperature.

Barrel Temperature: It influences on the melting state and flowability of the plastic. It is often segmented into several heating areas, where each area’s temperature regulation is based on the nature of the material to be processed.

Nozzle Temperature: Affect the movement and injection impact of the molten plastic. Either extremely high nozzle temperature and equally as low nozzle temperature can affect the product quality.

Mold Temperature: Influences the rate at which the plastic cools and the shape of the final output. A properly controlled mold temperature can help avoid cases of warping and shrinking of the injection molded parts. Mold temperature affects the cooling rate and final product dimensions.

Pressure Adjustment

Injection pressure and holding pressure are two critical pressure parameters in injection molding.

Injection Pressure: It stands for the force exerted during the process of injecting the plastic melt into the mold. Oil pressure in the hydraulic system directly influences injection pressure. Correct injection pressure also helps in packing the mold optimally, thus preventing common issues such as short shots and flashes.

Holding Pressure: After injection, it has to maintain a certain pressure to avoid backflow of the melt and also product shrinkage. Therefore, how long this holding pressure is applied, as well as the level of holding pressure, has to be adapted according to the particular specifications of a given product. Back pressure during the injection phase also impacts the quality of the final product.

Speed Adjustment

Injection speed and mold opening/closing speed are also crucial parameters to adjust.

Injection Speed: This affects the rheological behavior and filling action of the plastic melt. Different products and mold structures require different injection speeds to ensure product quality and production efficiency. Screw speed during injection plays a significant role in determining how well the material fills the mold.

Mold Opening/Closing Speed: It affects the mode of operation of production and the duration of the molds. Moderate speeds will help increase productivity and at the same time help extend the life of molds.

Time Adjustment

Several time aspects in the injection molding process optimization, these are injection time, holding time, cooling time, and mold opening/ closing time.

Injection Time: The injection time is the time for the plastic melt to be injected into the mold. Injection time that is too short or too long is not favorable because they have a negative impact on the quality and production efficiency of the produced products.

Holding Time: The time to maintain the injection pressure, which affects the density and dimensional stability and precision of the product.

Cooling Time: The time required for the plastic melt to cool and solidify in the mold. Proper cooling time can minimize product warping and deformation.

Mold Opening/Closing Time: The time for the mold to open and close, which affects the production rhythm and mold life.

Specific Steps for Injection Molding Machine Adjustment

Preparation

Inspect Equipment: Inspect the injection molding machine to confirm that it is working as required and does not have any damages or faults before any adjustments are made to it.

Select Material: Select the right type of plastic and confirm its quality and characteristics according to the produced goods.

Clean Mold: Remove any debris that may be on the mold surface because it might contaminate the end product.

Temperature Adjustment

Set Barrel Temperature: Set the temperature at which each heating zone will be required for the intended material and for the conditions of the process.

Set Nozzle Temperature: Modify based the characteristics of the material and the injection process that is to be used.

Set Mold Temperature: Based on the form and dimensions of a specific product, configure.

Pressure Adjustment

Set Injection Pressure: Adjust according to material flowability and mold structure.

Set Holding Pressure: Based on density of the product and its dimensional stability necessities, it should be configured to the right type.

Speed Adjustment

Set Injection Speed: Depends on the flowability of the material as well as the structure of the mold.

Set Mold Opening/Closing Speed: Depending on its mold life span and the requirement of the production rhythm that needs to be maintained.

Time Adjustment

Set Injection Time: Depending on the type of product, it has to be adjusted depending on the size and the shape of the product.

Set Holding Time: Configure based on product density and dimensional stability requirements.

Set Cooling Time: Modulate depending on the requirement that the product needs for cooling.

Common Problems and Solutions in Injection Molding Machine Adjustment

Air Bubbles

Causes: Low injection pressure, too fast injection speed, or low mold temperature can cause bubbles. Bubbles inside the product are usually caused by uneven flow of the plastic melt in the mold, which eventually traps gas or air. Low injection pressure can cause voids to form because the mold may not be fully filled, while high injection speeds can cause air to be trapped as the melt flows, and low mold temperature can cause premature cooling of the melt, which traps gas.

Solutions: Increasing injection pressure, reducing injection speed, and increasing mold temperature are solutions to the bubble problem. Increasing injection pressure ensures that the mold is fully filled and reduces voids, on the other hand, reducing injection speed minimizes air entrapment, and increasing mold temperature prolongs cooling time and allows gas to escape.

Shrinkage

Causes: Holding time, holding pressure control or mold temperature control can cause product shrinkage, which may be caused by short holding time, low holding pressure or high mold temperature. Shrinkage is usually caused by the plastic melt reducing in size during solidification. Short holding time may prevent full filling during cooling, low holding pressure may cause the melt to flow back and form voids, and high mold temperature may slow down the cooling rate, which increases the possibility of shrinkage.

Solutions: Increase the holding time, holding pressure, and lower the mold temperature. Increasing the holding time allows the mold to have enough time to fill during cooling, increasing the holding pressure can reduce the reflux of the melt and increase the filling density of the product, and lowering the mold temperature can accelerate cooling and reduce shrinkage.

Warping

Causes: Too short cooling time, too high injection speed and poor mold design can all cause product warping. Warping is usually caused by uneven stress distribution in the plastic melt during cooling, which causes shape changes. Too short cooling time is not conducive to structural stability, too fast injection speed can lead to uneven internal stress, and improper mold design can lead to uneven stress during cooling.

Solutions: Cooling time should be increased, injection speed have to be decreased, and the design of the molds should be improved. The cooling time slows down to enhance the constancy of the internal arrangement that results in lesser distortion, slowing down the rate of injection helps to reduce the amounts of internal stresses, an effective design of the mold ensures distribution of equal stresses of cooling.

Deformation

Causes: Too high injection pressure, too short cooling time and too high mold temperature may cause product deformation. The most common cause of deformation is the difference in volume and stress of the plastic melt during cooling.

Solutions: Reduce injection pressure, extend cooling time, and reduce mold temperature. Reducing injection pressure can reduce internal stress and deformation, extending cooling time can stabilize the internal structure, and reducing mold temperature can accelerate cooling and reduce deformation.

Surface Defects

Causes: slow injection speed, low mold temperature or inappropriate material selection. Surface defects are usually caused by uneven flow of plastic melt in the mold, such as flow marks, weld marks and so on.

Solutions: Increase injection speed, mold temperature, and select appropriate mold materials.

Conclusion

Regulating injection molding machines is very important to achieve the quality and efficiency of the products to be produced. By properly adjusting temperature, pressure, speed and time, etc., it can have a positive impact on product quality, production intensity and service life of process equipment. Operators should have many years of experience and knowledge in operating mechanical equipment, and regularly conduct training and equipment maintenance to ensure a stable and efficient production process. This article aims to provide valuable insights to help readers better master the various methods and techniques for regulating injection molding machines.