Plastic Injection Molding
Plastic injection molding, with its high degree of automation, flexibility, environmental friendliness, recyclability, and precision, is widely used in various fields such as daily necessities packaging, automobiles, agriculture, industry, and aerospace, and gradually penetrates into people’s lives.
Injection Molding Companies|Design and Precautions
Injection molding companies generally provide plastic injection molding services to customers with professional design and rich experience and can make improvements according to requirements until the molds can be perfectly embedded in the production line.
Custom injection molding, with its high degree of automation, flexibility, environmental friendliness, recyclability, and precision, is widely used in various fields, such as daily necessities packaging, automotive, agriculture, industry, and aerospace, and has gradually penetrated people’s lives.
Key Points of Injection Mold Design
Although injection molding companies have a lot of experience in the design of injection molds, many of these key points cannot be ignored. In the design process, the following key points should be followed:
- Design Gap Adjustment Blocks on the Edge Pressing Ring
The three components of the quick mold, namely the concave mold, convex mold, and edge holder, are prone to gaps and poor surface uniformity due to factors such as the parallelism of the press, the consistency of the top rod height, and the flatness of the edge holder itself, which is very detrimental to the effectiveness of injection molding. If an adjustment block is added between the gap between the concave mold and the edge pressing ring, this defect can be better improved. At the same time, the design and installation of the adjustment block do not require a long time, and the efficiency is higher.
- Design and Processing of Guide Plates
Although the guide plate structure is now used in the mold, the injection molding companies cannot fully determine its accuracy and setting position, and it has not played a significant role in actual work. The processing of convex molds and edge ring guide plates has certain precision requirements, especially for complex-shaped irregular edge-pressing surfaces. To improve accuracy and reduce lateral forces during forming, guide plates need to be designed between the concave mold, convex mold, and edge-pressing ring.
- Design of Top Rod Position
From the on-site situation, it can be seen that in most cases, injection molding companies have not taken into account the design of the top rod position, which increases the difficulty of adjusting the mold. This can easily lead to a reduction in the number of top rods used, longer machine operation time, and a reduction in the working surface of the top rod. At the same time, they have not taken into account the design of the convex mold pressing angle, and cannot find a suitable position to press the convex mold tightly. The contact surface between the edge pressing ring and the top rod adopts a convex form, which can reduce the processing area and weight. At the same time, the angle of the edge-pressing ring can be adjusted when needed.
Design Key Points for Filling Speed of Injection Mold Cavity
When designing in injection molding companies, there is often an issue of uneven filling speed among various cavities inside the mold. At this time, the design and adjustment of the filling speed of the cavities are crucial. The following are the key points for designing the filling speed of the cavity:
- Properly increasing the gate and runner can correspondingly increase the injection pressure and speed of the mold cavity, but if it is too large, it may have a counterproductive effect. If this method is applied properly, it can effectively adjust the filling speed of each cavity.
- The gate positions of each cavity can be set to be uneven to meet the different pressure and speed requirements of each cavity. In the production process, it is common to expect the pressure or speed of a certain cavity to be high, but the pressure and speed of other cavities will not increase with it, and sometimes it may even need to be reduced. For example, if an injection molded part in one cavity has a defect in airlines, but another cavity has a defect of insufficient filling, slowing down the injection speed can solve the problem of airlines, but solving the problem of insufficient filling requires slowing down the filling speed or adjusting the shrinkage speed.
- Adjust the filling speed of each cavity to be consistent, so that the filling progress of injection molded parts in each cavity is as consistent as possible, which can effectively solve the problems of uneven filling or shrinkage. Adjusting the filling speed can also enable multiple injection parts in the same mold of multi-stage injection molding to be upgraded at the same position so that the same injection problem will not occur.
Key Points for Selecting Plastic Raw Materials for Injection Molds
When selecting plastic raw materials for injection molding companies, due to the wide variety of plastics and the similar performance of most plastics, they need to focus on whether the selected plastics can meet the requirements of the injection molding process and whether they can achieve the functional use of the molded parts.
The selection of materials needs to meet the requirements of the injection molding process. When selecting materials, the performance of the materials should be divided based on the structure of the mold, and the size and quality of the product. For example, the difference in shrinkage rate between plastics, the quality of fluidity, crystallinity, and temperature sensitivity should be considered. Suitable plastic raw materials should be selected according to the injection molding process.
To achieve the final performance requirements of plastic parts, it is important to focus on the usage environment and precision requirements of plastic products. It is necessary to consider the mechanical and physical properties of plastics, such as toughness, elasticity, rigidity, strength, impact resistance, bending resistance, temperature adaptability, insulation, optical properties, and sensitivity to stress. Only after comprehensive consideration can suitable raw materials be selected; Consider the chemical properties of plastics, such as their resistance to contact materials (oil, water, drugs, solvents), and whether their safety characteristics meet the requirements.
When selecting materials based on the performance data of plastic raw materials, the difference in performance between metal and plastic parts should be considered. Most of the performance data of metals are similar to the screening of materials, but for plastics with certain viscosity and elasticity, various data and testing standards are specific, usually measured in a short period or at specified temperatures. These specific conditions may differ significantly from actual operations, especially as they cannot be used as a reference for the strength and suitable temperature of plastics. All plastics must consider their actual usage when selecting materials based on their performance. If the plastic used is not suitable, adjusting the parameters of the mold and the data of the injection molding machine in the later stage will require a considerable amount of effort and time.
Precautions for Companies in Injecting Products with High Transparency
For injection molding companies, the production of products with high transparency or white color is quite difficult, and many design points can avoid problems such as black spots or bubbles in the manufacturing process.
- All plastic raw materials that have been recycled, packaged, or mixed in color, and proportioned must be immediately sealed and marked after being placed in the bag to prevent mixing or water absorption that requires re-drying.
- Before crushing or mixing materials, it is necessary to clean the plastic machine and barrel to ensure that there are no foreign objects before proceeding with the operation.
- When crushing or mixing, if there are black spots or other colors in the material, these different colored plastics should be removed before processing.
- Bags or other containers containing mixed materials must be kept clean and dry.
- The material in the hopper should be added to a certain extent. If it is too full, it is easy to overflow. After adding the material, the lid should be promptly closed to prevent dust from the air from falling into the material barrel and causing pollution to the material.
- The machine position drying bucket should be ensured to be clean, and the air inlet should be covered with dust-proof cloth or other materials to prevent dust from being sucked into the drying bucket.
- Before adding materials, it is necessary to clean the dust on the bag. If the plastic materials in the bag are not used up in one go, the bag mouth should be sealed back promptly to prevent moisture.
- If there are serious black spots or other problems with the product, it should be disposed of as waste and the black spots should be picked out before continuing to be recycled.
- When filling a basket with water or waste, it should be crushed promptly. If they need to be temporarily stored, they should also be covered with a lid or film.
- When recycling materials and waste from the water outlet, it is also necessary to clean the recycling bucket or recycling frame before storage.
When adjusting the mold, the operator needs to wash their hands or wear gloves before taking and placing the product, otherwise the product will leave dirt and stains that need to be cleaned, increasing the workload.
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