Injection speed and section control of injection molding machine

The close relationship between injection speed and product quality makes it a key parameter of injection molding. By determining the beginning, middle, and end of the filling speed segment, and realizing a smooth transition from one set point to another set point, a stable melt surface speed can be ensured to produce the desired molecule and the smallest internal stress. This article mainly introduces the injection speed, as well as the segmented control, principles, basis and calculation of the injection speed. I hope you have a deeper understanding of the injection speed.

What is injection speed?

Injection speed refers to the filling speed of the mold when the screw is used as a punch. When injecting thin-walled products, a high rate of shot must be used so that the mold can be completely filled when the melt is not solidified to produce a smoother surface. A series of programmed firing rates are used when filling to avoid defects such as jetting or trapped air. No matter what kind of injection speed is used, the speed value must be recorded on the record table together with the injection time. The injection time refers to the time required for the mold to reach the predetermined first-stage injection pressure, which is part of the screw advance time. Injection can be carried out under an open-loop or closed-loop control system.

Injection speed and segment control

Injection molding machines often have multi-stage injection pressure and multi-stage injection speed control functions, which can better ensure the quality and accuracy of products. The injection pressure and injection speed can be set and adjusted on the control panel. Either one-stage injection or multi-stage injection can be used. Generally, one-stage glue injection can reduce the loss of equipment caused by frequent pressure and speed changes. The use of multi-stage glue injection can reduce bubbles and pores on the silver pattern surface. When using multi-stage glue injection, the glue injection position should be set correctly, otherwise the multi-stage glue injection will not work. In production, it can be adjusted appropriately according to the nature of the product.

The principle of injection speed segmentation

It is generally recommended to use the following speed segmentation principle:

1) The velocity of the fluid surface should be constant;

2) Fast injection should be used to prevent the melt from freezing during the injection process;

3) The injection speed setting should take into account the rapid filling in the critical area (such as the runner) while slowing down the speed at the water inlet level;

4) The injection speed should be guaranteed to stop immediately after the cavity is filled to prevent over-filling, flashing and residual stress.

The basis for setting the speed segmentation must take into account the geometry of the mold, other flow restrictions and unstable factors. The speed setting must have a clear understanding of the injection molding process and material knowledge, otherwise, the product quality will be difficult to control. Because the melt flow rate is difficult to directly measure, it can be calculated indirectly by measuring the screw forward speed or cavity pressure (make sure that the check valve is not leaking).

Guangdong Polyrocks Chemical Co., Ltd. is a modified plastics company with 21 years of sales, R&D and production experience. It has an annual production capacity of 100,000 tons of modified plastics. It has environmentally friendly modified polyolefin materials, modified engineering plastics and More than 200 brands of products such as functional masterbatch. The products have passed the IATF16949 quality management system certification, passed the American UL certification, and comply with the European Commission RoHs standard; and are widely used in automobiles, smart home appliances, lighting, environmental protection cables, OA equipment, communication electronics, sanitary plastics, televisions, coatings and other industries .

Since its establishment, Polyrocks Chemical has undertaken a number of provincial and municipal level science and technology projects every year, and currently has a number of invention patents for core technologies of flame retardant materials at home and abroad. Has been committed to the development of halogen-free flame-retardant environmentally friendly flame-retardant materials industry, and realized the industrial transformation from domestic sales to export sales through global management, and continuously maintained high technical content and high added value through technological innovation and product innovation.