Plastic Injection Molding Manufacturers | Strict Quality Control for Best Products
Plastic Injection Molding
Details
Details:
Model
Material
Brand
Origin
Application
Booling-Injection-1
P20, 718, S136, 2738 etc
Booling
China
Automotive parts, industrial parts, medical parts, household
In the field of plastic injection molding technology, manufacturers mainly pursue the best product performance through material selection, adjustment of molds, machines, and process parameters, as well as subsequent annealing and dehumidification treatment of finished products.
Advantages of Plastic Injection Molding：
- High Precision and Repeatability
- Low Cost per Part
- Fast Production Rate
- Wide Material Choice
- Little Waste
Related Hot Products
Modern plastic injection molding manufacturers have professional technology and equipment to design and develop high-precision and high-quality molds for production, providing excellent plastic injection molding services. Injection molds are tools used for custom injection molding production, and the application of injection molding production is usually very extensive. It mainly involves fields such as medical equipment, daily necessities, electrical and electronic equipment, building materials, the automotive industry, agriculture, etc. It can be said that it is spread throughout every corner of daily life.
Best Solutions of Welding Marks
The most common problem encountered by injection molding manufacturers during product manufacturing is the easy formation of weld marks, and there is a significant difference in the color of the plastic on both sides of the weld marks. For this situation, injection molding manufacturers have a set of strict quality inspections to solve it.
- The Gate Position is Unreasonable
Efforts should be made to minimize the diversion of the gate and select a reasonable gate position to maintain a consistent filling rate and prevent filling interruptions. When conditions are suitable, try to choose a single-point feeding method. While increasing the temperature of the mold, one or more cold material cavities can also be set inside the mold, which can prevent low-temperature melt that has not been fully plasticized from entering and mixing with high-temperature melt, resulting in weld marks.
- The Melt Temperature is too Low
When the fusion marks generated on the inner and outer surfaces of the plastic part are in the same position, it is necessary to consider whether it is caused by the low temperature of the melt. At this point, injection molding manufacturers can increase the temperature of the nozzle and barrel, or prolong the melting time of the plastic in the mold cavity. It is also possible to increase the temperature of the mold by reducing the amount of cooling water. The areas where welding marks are produced in plastic parts will have lower strength and poorer performance. If it is necessary to improve the strength of the welding marks, the corresponding parts can be heated. If the process and raw materials used cannot be processed at high temperatures, the quality of the welding marks can be strengthened by increasing the injection speed and pressure.
- Improper Use of Release Agent
In the injection molding process, injection molding manufacturers generally rarely use release agents and only use them when it is extremely difficult to release.
- Unreasonable Structural Design of Plastic Parts
If the thickness of the plastic part is too thin or there is a significant difference in thickness, as well as excessive use of metal inserts, it can lead to welding marks in the plastic part. When setting parameters, it is necessary to ensure that the thickness of the plastic part wall is within the specified allowable range. Whenever possible, the use of metal inserts should also be minimized.
- Poor Mold Exhaust
In the event of poor exhaust, the manufacturer should consider whether the exhaust hole is blocked and whether there are foreign objects in the gate. If the problem of welding marks still exists after removing foreign objects, it can be considered resetting the gate to increase the number of exhaust holes at the material collection point, or appropriately reduce the locking force and increase the size of the exhaust holes. The occurrence of weld marks can also be avoided by changing the injection molding process, such as reducing material temperature, barrel temperature, mold temperature, injection pressure, and time.
- Other Reasons
The plastic raw materials used have a high water content, the oil stains generated during the last use of the mold were not cleaned promptly, there is unmelted plastic in the mold cavity or it is not filled evenly, and the cooling time of the melt is too short and the speed is too fast, the temperature difference between the insert and the plastic is too large, and the nozzle hole is too small. These reasons may all lead to the appearance of welding marks. In the production process, different response measures should be taken for different situations. For example, measures such as drying according to the melting point of plastic, cleaning the material barrel, cold runner, and other parts of the mold, controlling and changing the flow and direction of cold water flow, preheating metal inserts in advance, increasing the diameter of nozzles, and replacing injection molding machines can be taken to solve the problem.
Improvement Methods for the Weak Encapsulation of Glue
When the injection molding manufacturer is processing, the quality inspection department finds that the secondary soft rubber coating of the plastic parts is not firm, that is, the packaging is not firm, then it is necessary to immediately analyze the cause and propose a solution, otherwise it will affect the subsequent processes.
- Main Production Processes and Causes of Defects:
The main process of secondary encapsulation molding: use the first type of plastic to shape the inner parts; Rotate the moving mold and then use a second type of plastic to shape the outer parts, so that the outer parts can be stacked on top of the inner parts. Common examples include electronic products such as mobile phone casings. For other industries, such as the electric tool industry, the molded parts often need to be divided into two sets of molds. The first set of molds is used to form the inner layer of the parts, the second set of molds is used for gluing, and the second layer of plastic is generally thermoplastic elastomer material. The most common defects of this process are weak gluing, insufficient aesthetics, and short shots.
- Common Solutions for Weak Adhesive Wrapping are as Follows:
- Immediately after the injection molding is completed, the double-color injection molding has the best effect.
- When injection molding with adhesive, the cleanliness of the inner layer material’s adhesive area must be high, but it is best not to manually clean it, to achieve no oil stains or dust.
- After discovering the problem of loose glue wrapping, the outer soft glue should be immediately removed. At this time, it is not allowed to carry out secondary glue wrapping operations.
- During injection molding, to improve the firmness of adhesion, both the injection speed and melt temperature should be increased.
- The effect cannot be immediately judged after gluing, and the quality of the plastic parts should be tested after being left for some time.
- The surface of the coated area should avoid the use of release agents as much as possible to prevent reactions that may cause damage to the plastic parts.
- When there are problems with plastic raw materials, injection molding manufacturers should consider both the inner and outer layer materials.
Solutions to the Shrinkage Problem of Plastic Parts
When faced with the problem of shrinkage of plastic parts, the quality inspection department of the injection molding manufacturer will find that the shrinkage problem mostly occurs in areas with thicker plastic walls. The main reason is that the molten material cannot be replenished in time during the cooling process of the plastic parts. At this time, the manufacturer cannot solve this problem no matter how much the gate or pressure is increased. However, after a long period of practice, the injection molding manufacturers have gradually found a solution.
- On the premise of ensuring the shape quality during the demolding of injection-molded parts, the cooling time should be shortened as much as possible to allow the injection-molded parts to be demolded early at high temperatures. At this point, the outer layer temperature of the injection molded part is not completely cooled and remains relatively soft, greatly reducing the temperature difference between the inside and outside, which is conducive to overall shrinkage and thus reduces the risk of concentrated shrinkage inside the injection molded part. Due to the fixed overall shrinkage of injection molded parts, the overall shrinkage and concentrated shrinkage are inversely proportional.
- Due to the temperature rise on the surface of the mold and the decrease in cooling capacity, the solidified injection molded surface is still relatively soft and not completely hardened. The internal shrinkage holes that have not been eliminated gradually become in a vacuum state. The surface of the injection molded part is compressed inward under atmospheric pressure, resulting in the so-called shrinkage problem. The slower the rate of surface hardening, the easier it is for shrinkage problems to occur, such as in polypropylene materials. But the faster the surface hardening rate, the easier it is to produce shrinkage cavities. Therefore, if the injection molded part is de-molded early, it needs to be cooled for a certain period to maintain a certain hardness on the surface and prevent shrinkage. But if moderate cooling cannot solve the problem of shrinkage, the method of freezing water should be adopted to rapidly harden the surface of injection molded parts. Even if this method can improve shrinkage, there will still be internal shrinkage.
- If the effect of the above measures is still not ideal, extending the injection time can be used instead of cooling time to achieve better results.
- When solving the problem of shrinkage, too low a mold temperature can also aggravate the shrinkage. Therefore, it is best to cool the mold with machine water instead of using frozen water. If necessary, the mold temperature can also be raised. For example, when the injection molding material is polycarbonate, the mold temperature can be raised to 100 ℃, which can achieve better improvement effects. However, excessively high mold temperatures often fail to solve the problem of shrinkage.
Related News
Applied’s expertise in modifying materials at atomic levels and on an ihdustrial scaleenables our customers to transform possibilities into reality.
