PVDF processing molding method

1. Extrusion molding

PVDF can be made into films, sheets, tubes, rods and power insulation sleeves by extrusion molding. Generally, the resin is required to have better melting fluidity and better stability.

2. Injection molding

Low molecular level of PVDF melting flow speed is high, can be processed by injection molding method, its advantages are high production efficiency, low labor intensity, good product appearance.

3. Casting molding

Casting molding is based on dimethylacetamide as a solvent, PVDF is configured into a solution with a solid content of 20%, and it is cast on aluminum foil. After hot melting at 205 ~ 315 degrees Celsius, a continuous strong film with a thickness of 0.05 ~ 0.075mm can be made by quenching with water.

4. Molding

PVDF with molecular weight of more than 500,000 has poor melting fluidity and good forming stability. PVDF resin mainly adopts two processing methods of ordinary molding and transfer molding, mainly used for the production of products with large wall thickness, such as: corrosion resistant thick plate, pipe fittings, pumps, valves, containers, etc.

5. Other processing methods

PVDF can also be processed by dipping, co-extrusion, composite and other processing technologies.

PVD processing and production steps

1. Raw material preparation

Select high purity PVDF as raw material, and add various auxiliary agents as needed.

2. Synthetic reaction

The PVDF resin was dissolved in surfactant and the polymerization was carried out by adding initiator. The reaction results in a high polymer.

Step 3: Filter

The synthetic polymer is filtered through a strainer or screen to remove impurities from it.

4. Deformation processing

The PVDF polymer is made into the desired shape and size by extrusion, injection molding and other processing methods.

5. Film preparation

The PVDF polymer was dissolved in a suitable solvent and the PVDF film was prepared by spinning coating or stretching the film.

6. Secondary processing

Deep processing of PVDF products, such as surface treatment, cutting, assembly, etc.

Step 7 Test

Through physical property testing and chemical analysis, PVDF products are tested to ensure that the quality meets the requirements.

The PVDF production process requires strict control of all aspects to ensure product quality and stability. It is also necessary to strictly screen and monitor the quality of raw materials to ensure that the raw materials of the product are safe and reliable.

Difficulties of PVDF machining

1. Large cutting force

Due to the low hardness of PVDF, it is easy to produce plastic deformation and vibration during processing, resulting in large cutting force. This will not only affect the quality of the processing, but also may cause damage to the machine tools and tools. Therefore, it is necessary to fully consider the influence of cutting force when selecting tools and cutting parameters.

2. Soften on high heat

PVDF has high melt viscosity and good thermal stability, but it will soften at high temperatures. This causes PVDF to easily deform and flow during processing, which affects processing quality and efficiency. Therefore, it is necessary to preheat PVDF during machining to improve its thermal stability.

3. Grinding is difficult

Because of the low grinding coefficient of PVDF, the grinding process is more difficult. In addition, it is easy to generate sparks during high-speed grinding, which leads to cracks and defects on the workpiece surface. Therefore, when grinding, it is necessary to select the appropriate grinding wheel and cutting parameters, and carry out adequate coolant injection. At the same time, measures should be taken to prevent sparks.

4. Drilling is difficult

PVDF has good drillability, but it is easy to crack and deform in the process of high-speed drilling. In order to avoid the occurrence of cracks, measures such as low-speed drilling, proper cooling and lubrication can be used. In addition, dust and impurities are easily absorbed during the drilling process, so it is necessary to regularly clean the drill and workpiece surface.

5. Welding difficulties

Although PVDF has good welding performance with various metal substrates, there are also some difficulties in the welding process. It is easy to produce bubbles and cracks at high temperature. The problem of poor fluidity is easy to occur at low temperature; At the same time, it is also necessary to pay attention to controlling factors such as welding temperature and pressure.

6. Stress concentration

Due to the small thermal expansion coefficient of PVDF, it is easy to produce stress concentration in the process of processing. This can lead to problems such as cracking or deformation of the workpiece during use. Therefore, the workpiece needs to be properly prestressed before machining to reduce the impact of stress concentration.

Guangzhou OTEM Engineering Plastics Co., Ltd. has more than 20 years of PVDF, PFA, PTFE, FEP and other fluorine plastic products processing experience, we also have more than 2,000 square meters of physical processing plant, while with professional production equipment and professional design team, can bring you professional and satisfactory products and services.

PVDF processing needs attention

1. The injection molding machine has various mechanical movements such as high temperature, high pressure, opening and closing, and transmission, so we must attach great importance to safe operation and pay attention to wearing protective tools such as protective covers and labor protection shoes.

2. No one is allowed to enter the cabin when discharging materials. Clean the nozzle in time after discharging materials, otherwise it is easy to damage the heating ring.

3. The maintenance must first check whether the safety device is reliable, and then turn off the pump for maintenance. When the billet is stuck on the mandrel, pay attention to the way and method to avoid damaging the mold.

4. No one is allowed to enter the cabin during production. If you must go in to observe and adjust the machine, there must be two operators present, one person goes in to adjust and stands in a relatively safe position, and the other person monitors outside to prevent others from fiddling with the equipment to ensure safety.

5. In case of fire, do not use water to extinguish it. First turn off the power, and then use a dry powder extinguisher to extinguish the fire.

6. The body is equipped with multiple emergency stop devices. In case of emergency, you need to press the emergency stop button.

7. It is forbidden to change or disassemble the safety device without permission.