The molding process of plastic LCD back cover is detailed

The molding process of the plastic LCD back cover usually involves injection molding technology, which is a process in which molten plastic is injected into a mold and cured by cooling to form a product of the desired shape and size. The following is a detailed analysis of the plastic LCD back cover molding process:

First, injection molding process overview

Injection molding is a widely used plastic processing technology, which is suitable for manufacturing plastic products with complex shape, accurate size and large batch. In the production of LCD rear covers, injection molding technology is favored for its efficiency, precision and repeatability.

Second, injection molding process steps

Plastic raw material preparation:

The selection of plastic raw materials suitable for the LCD back cover requirements, such as ABS, PC, PMMA, etc., these materials have good mechanical properties, heat resistance and chemical corrosion resistance.

The plastic raw material is made into a granular form for easy feeding and plasticizing.

Plastic melting:

The plastic particles are put into the hopper of the injection molding machine, and the plastic particles are melted and mixed evenly through the rotation and heating of the screw to form a molten state of plastic.

The melting temperature is set according to the type of plastic and mold requirements, usually within the range of tens of degrees of the melting point of the plastic.

Mold preparation:

Design and manufacture injection molds that conform to the shape and size of the LCD back cover.

The mold is usually composed of two parts: the moving mold and the fixed mold. The two parts are tightly closed by the mold closing mechanism to form the mold cavity.

A cooling channel is set up in the mold to quickly cool the plastic during injection molding.

Injection Molding:

When the mold is closed, the injection molding machine injects the molten plastic into the mold cavity through the nozzle.

Injection pressure and speed are set according to the type of plastic, mold structure and product requirements to ensure that the plastic can adequately fill the mold cavity and remove air.

Pressure holding and cooling:

After the plastic is filled with the mold cavity, the injection molding machine continues to apply a certain pressure (pressure retention) to prevent the plastic from shrinking or indentation due to cooling shrinkage.

At the same time, the cooling water channel in the mold begins to work, and the plastic is quickly cooled to the curing temperature by circulating the cooling water.

The holding pressure and cooling time are set according to factors such as the type of plastic, mold structure and product thickness.

Opening and picking up:

When the plastic is fully cured, the mold closing mechanism of the injection molding machine opens the mold to reveal the formed LCD back cover.

Use a mechanical arm or manual to remove the formed LCD back cover from the mold, and remove the remaining material such as the gate.

Post-processing:

Take out the LCD back cover quality inspection, including appearance inspection, size measurement and performance test.

Surface treatment as required, such as spraying, printing or coating, to enhance the appearance and performance of the product.

Third, the key parameters of injection molding process

Injection pressure: affects the filling speed of the plastic and the pressure distribution in the mold cavity, which in turn affects the density and dimensional accuracy of the product.

Injection speed: affects the flow state and filling effect of the plastic, too fast injection speed may lead to defects on the surface of the product.

Melting temperature: affects the fluidity and viscosity of the plastic, which in turn affects the molding quality and performance of the product.

Mold temperature: affects the cooling rate and curing effect of plastics, which in turn affects the dimensional accuracy and surface quality of products.

Pressure holding time and pressure: it affects the shrinkage rate and density distribution of the product, which in turn affects the dimensional accuracy and mechanical properties of the product.

Fourth, the advantages of injection molding process

High efficiency: The injection molding process can realize automatic production and greatly improve production efficiency.

Accuracy: The injection molding process can produce products with complex shapes and precise dimensions.

Repeatability: The injection molding process is highly repeatable and can ensure the stability of product quality.

Wide material adaptability: injection molding process is suitable for a variety of plastic raw materials, can meet the needs of different products.

Fifth, the precautions of injection molding process

Mold design: Mold design should fully consider the shape, size and performance requirements of the product, as well as the injection capacity of the injection molding machine.

Selection of raw materials: Appropriate plastic raw materials should be selected according to the use environment and performance requirements of the product.

Adjustment of process parameters: The injection molding process parameters should be adjusted according to the type of plastic, mold structure and product requirements to ensure the molding quality and performance of the product.

Quality control: A perfect quality control system should be established to strictly control all aspects of the injection molding process to ensure the stability of product quality.

In general, the plastic LCD back cover molding process involves a number of links and key parameters, the need to comprehensively consider product requirements, raw material characteristics and injection molding machine capacity and other factors, through continuous optimization of process parameters and mold design, improve the quality and performance of the product molding.