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The Development Trend of Thin-walled High-speed Injection

Sunbun

Thin wall plastic product display

Thin-walled plastic products are widely used in aerospace, dining tables, medical and health, electronic products and other industries because of their ease of recycling and low environmental pollution. High-speed thin-wall injection molding machine can save materials and time, and is one of the important production equipment for plastic products in the future.


Current status of thin-walled parts

The cost of plastic raw materials usually accounts for about 50-80% of the product cost, which is quite alarming. Thin-walled manufacturing helps reduce this ratio. In particular, the design of daily plastic products related to consumer lunch boxes, medical supplies, and electronic products is getting thinner and thinner. Thin-walled products have become the goal pursued by the plastics consumer industry due to the advantages of reducing product weight and dimensions, easy integrated design and assembly, shortening production cycles, saving materials and reducing costs. At present, thin-walled products have become a new trend in the plastic molding industry. One of the research hotspots.

 

Factors affecting thin-walled parts

Thin-walled products refer to workpieces with relatively thin wall thickness, which are called thin-walled parts. In the industry, workpieces with a wall thickness of less than 1mm are called thin-walled parts. This article mainly discusses the injection of thin-walled parts. In the injection molding process, the definition of thin wall is related to the process/wall thickness ratio, the viscosity of the plastic and the heat transfer coefficient. The distance from the main runner of the mold to the farthest point of the finished product is called the process flow (indicated by L), divided by the wall thickness of the finished product (indicated by t), is called the process/wall thickness ratio. When L/t>150, it is called thin wall. If the thickness of the process is inconsistent, the process/wall thickness ratio can be calculated in sections. The viscosity factor of polypropylene (PP) is 1. The process flow of the disposable lunch box is 135mm, the wall thickness is 0.45mm, and the process/wall thickness ratio=300. The viscosity factor of polycarbonate (PC) is 2. The process flow of the cell phone battery case is 38mm, t=0.25mm, and the process/wall thickness ratio=152. Therefore, the viscosity of the plastic is the key to the finished product.

 

The relationship between thin-walled products and injection molding machines

The filling time of thin-walled injection molding is very short, and many filling times are less than 0.5 seconds. It is impossible to follow the speed curve or cut-off pressure in such a short time. Therefore, a high-resolution microprocessor must be used to control the injection machine; During the entire injection molding process, the pressure and speed should be controlled independently at the same time. The filling stage of the conventional injection machine is controlled by speed, and the method of switching to pressure control at the pressure holding stage is no longer applicable.

The high-speed injection machine is mainly aimed at products with relatively high cycle requirements and relatively thin wall thickness requirements. Similar to the unit time, the output is relatively large, the product structure is simple, and the product cost can be effectively reduced. The most familiar is the disposable thin-walled lunch box, Products such as disposable cups. At present, the best high-speed injection machines on the market include the VS-100 thin-walled injection machine from Taiwan Zhongjing Machinery Co., Ltd., and the German Dr. Boy type injection machine, Dakumar high-speed machine, WITTMANN BATTENFELD, ARBURG, Japan Steel JSW and China Sunban and other famous injection molding machine manufacturers developed special injection machines machine.

High-speed injection molding machine

 

Material requirements for thin-walled parts and reasonable control of cooling time

Thin-walled high-speed injection molding materials must have the following characteristics: good fluidity; high impact strength; high thermal deformation temperature; good dimensional stability; high heat resistance of the material; good flame retardancy; high mechanical assembly; appearance Good quality effect etc.

At present, the commonly used materials for thin-wall injection molding include polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), and PC/ABS blends, etc. Materials suitable for thin-wall injection must have higher flow Once the fluidity of the raw material is not good, it can only be improved from the equipment, such as increasing the material temperature, high speed and high pressure, using the oil temperature machine or hot runner effect to improve the fluidity of the raw material to achieve the purpose of producing qualified products.

The cooling time accounts for 80% of the injection molding cycle. Only by accurately evaluating the cooling time of the plastic part can the molding cycle of the plastic part be accurately evaluated. The cooling time is related to the raw material, product wall thickness, injection temperature, mold temperature, etc.

 

Development and application of high-speed injection technology

With the rapid development of polymer materials and manufacturing, engineering plastics are widely used in precision instruments, electronic meters, audio and video products, medical equipment, communication equipment, and optical lenses. Most of these plastic products are small in size, small in mass, complex in shape or ultra-thin wall, and their dimensional accuracy, form and position error, quality stability, apparent quality and other parameters are all required to be high. High-speed injection is imperative. At present, the high-speed injection technology is mainly divided into full hydraulic high-speed machine, all-electric high-speed machine and electro-hydraulic compound high-speed machine according to the driving mode. The early high-speed injection technology is all hydraulic, which has many unique advantages in forming precise and complex-shaped products, but its control technology is difficult, the machining accuracy is high, and the hydraulic technology precision control is also difficult to master.

Due to the mature application of the servo motor and the substantial drop in price, as well as the need for environmental protection and energy saving, in recent years, there are more and more all-electric high-speed injection technologies. They have advantages in environmental protection and energy saving, but they are not as good as all in terms of service life. Hydraulic injection molding machine and high cost. Therefore, it is imperative to develop an electro-hydraulic compound high-speed machine. It is a new type of injection machine that integrates hydraulic and electric drive, combining the advantages of a fully hydraulic injection molding machine in molding precision and complex shapes, and a fully electric positioning accuracy. And the advantages of energy saving, low noise, and the cost is lower than the all-electric injection molding machine.

The development and application of high-speed injection technology has greatly promoted the technical level of domestic injection molding machines, especially the design and development level and level of precision series injection machines, and has a significant role in promoting the development and competitiveness of the domestic plastic machine industry. significance.

High-speed injection is mainly used in the following areas: various thin-walled products of PP, PE, PS, such as disposable lunch boxes, aviation cups, IML boxes; high-volume products, such as syringes and precision industrial accessories, etc. This type of product is a consumable, with a large market gap, and this type of product is easy to recycle, can be classified into other products, recycled, and will not cause environmental pollution, and has a broad market prospect.

 

Conclusion

For small and medium-sized enterprises that need to produce thin-walled products, it is a good way to choose high-speed injection molding machines for production. If you need to buy a high-speed injection molding machine, you can click here to view related machines or contact us!

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