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PEEK injection mold process requirements

1. Injection requirements

Pressure: General injection pressure 70-140Mpa, injection speed: medium to high speed, back pressure: it is recommended to set the back pressure to 0-1.0MPa(0-10 kgf/cm2).

2, screw requirements

It is recommended that the minimum length to diameter ratio of the screw L/D is 16:1, but the L/D ratio between 18:1 and 24:1 should be preferred.

3. Injection machine:

Conventional machines that maintain the melt temperature at 360-400 ° C can be applied.

4. Cylinder capacity

Due to the high processing temperature of PEEK polymers, the residence time of the material must be as short as possible. The ideal barrel capacity is 2-5 times the total injection weight.

5, nozzle and locking system

Install a heater large enough at the nozzle to prevent the cooling from producing "injection cold material". If the temperature drops below 343 ° C, the melt will cure very quickly.

6. Barrel temperature

The unenhanced level is 360-380 ° C, and the enhanced level is 380-400 ° C, and the ceramic heating ring is the best choice for the injection molding machine heating system. In order to smoothly feed, the feeding area of the cylinder must be water-cooled to maintain a stability of 70-100℃.

7, mold temperature

The surface temperature of the mold is 175-205 ° C, up to 220 ° C.

8. Mold design

The mold is heated by high temperature grease above 300℃, the mold steel is made of H13 or 8407 and other high temperature resistant grades, and the heat insulation board above 250℃ is installed on the mold (>8mm). In order to reduce heat dissipation, the thermal insulation layer can be added around the mold; The guide column adopts high temperature self-lubricating grade; The main channel is greater than 4mm, the taper is recommended to be 2°, the gate is ≥1mm(pure material), ≥2mm(reinforced material); The flow channel of the mold should be round or trapezoid.

9. Drying

The PEEK material is placed in an air circulation furnace and dried at 150 ° C for at least 3 hours, or at 160 ° C for 2 hours. The workshop must be kept clean, and other materials must be strictly prevented from mixing, PEEK processing temperature is as high as 350-400 ° C, and most other plastics will be seriously degraded when mixed, affecting product performance.

10. Thermal stability

The shutdown time of the melting process does not exceed 1 hour, and there is no obvious degradation of the material at 360 ° C. If the downtime exceeds 1 hour, the cylinder temperature should be reduced to 340 ° C, at which temperature the material can remain stable for several hours. If the down time is more than 3 hours, the barrel should be cleaned. It can be cleaned with some materials that can maintain stable properties at 380 ° C, such as polyether sulfone or polyether imide, or with low MFI polyethylene.

PEEK mold design process needs to follow the process and key points

1. Research before design

Understand product requirements and process parameters, including injection pressure, speed, holding pressure and time, etc., to provide reference for subsequent mold design.

2. Choose a reasonable mold structure

Due to the high performance and particularity of peek material, it is necessary to choose the appropriate mold material and structure to ensure the life of the mold and the quality of the product.

3. Analyze the molding of the product

Through the analysis of the size, shape, wall thickness and other factors of the product, the parting line and gate design of the mold are determined.

4. Optimize the runner and gate system

Choose a reasonable gate size and number to balance filling time and pressure, while optimizing the flow design to improve product quality and production efficiency.

5. Validation and improvement

6. Verify and improve the mold by testing and testing the quality of the product to ensure the stability and production efficiency of the product.

Attention should be paid to PEEK mold processing

1, mold heating distribution uniformity;

2. Gate and runner design should be half of the thickest wall thickness of super thick parts;

3, the injection pressure is set higher than half of the plastic;

4, for parts with high dimensional accuracy requirements, heat treatment should be carried out after injection molding;

5, mold and melt temperature is high, pay attention to safety, to prevent burns;

How to choose PEEK injection mold

1. Physical properties of materials

peek material has good mechanical properties, high temperature properties, chemical corrosion resistance and electrical insulation properties, good strength and rigidity, and can withstand long-term high temperature pressure deformation. Therefore, peek injection molds are often used to manufacture molds used at high temperature and pressure. When choosing peek injection molds, the appropriate materials should be selected according to the specific needs of production.

2. Mold design requirements

Mold design is also a factor affecting the choice of mold materials. The shape, size and structure of the mold will affect the choice of materials, and will also affect the cost, service life and maintenance difficulty of the mold. According to the characteristics of the mold to choose the material, in the case of ensuring the toughness of the mold, as far as possible to choose the material harder, in order to increase the service life and stability of the mold.

3. Economic factors

Economic factors are also a factor that can not be ignored in the selection of materials. peek material is a high-performance material, and its price is relatively high. Therefore, when choosing peek injection molds, economic factors should be considered comprehensively, and the appropriate peek material should be selected according to the cost and production needs.