What is the working principle of plastic extruder?

The extrusion mode of plastic extruder generally refers to melting plastic at a high temperature of about 200 degrees, and the molten plastic forms the required shape when passing through the die. Extrusion molding requires a deep understanding of plastic characteristics and rich experience in mold design, and it is a molding method with high technical requirements.

Extrusion molding is a method of heating and pressurizing in an extruder to make materials pass through the die continuously in a flowing state, also known as "extrusion". Compared with other molding methods, it has the advantages of high efficiency and low unit cost.

Extrusion method is mainly used for the molding of thermoplastics, and can also be used for some thermosetting plastics. The extruded products are all continuous profiles, such as pipes, rods, wires, plates, films, wire and cable coatings, etc. In addition, it can also be used for mixing, plasticizing granulation, coloring and blending of plastics.

Extruded products can be called "profiles", which are also called "profiles" because the cross-sectional shapes are mostly irregular.

After the development of 100 years, the plastic extruder has been derived from the original single screw into various models, such as twin-screw, multi-screw, and even no screw. The plastic extruder (main engine) can be matched with various plastic molding auxiliary machines, such as pipes, films, holding materials, monofilaments, flat wires, packing belts, net extrusion, sheets, profiles, granulation, cable coating and so on. , forming various plastic extrusion molding production lines to produce various plastic products.

Therefore, whether now or in the future, plastic extrusion molding machinery is one of the widely used models in plastic processing industry.

App application

1, food

With the emergence of industrial manufacturing, extrusion has been applied to the food processing of fast food and snacks, as well as its known uses in the manufacture of plastics and metals. The main function of extrusion was originally developed for conveying and shaping the fluid form of raw materials.

Today, extrusion cooking technology and capability have developed to complex processing functions, including: mixing, conveying, shearing, separation, heating, cooling, molding, co-extrusion, volatile substances and moisture emission, packaging, flavor generation and sterilization.

Some pasta, many breakfast cereals, pre-made cookie dough, some French fries and other products, some baby food, dry or semi-wet pet food and ready-to-eat snacks are mostly produced by extrusion. It is also used to produce modified starch and granular animal feed.

Generally, high-temperature extrusion is used to make instant snacks, and cold extrusion is used to make pasta and related products for later cooking. The moisture content of processed products is low, so the shelf life is quite long, which provides consumers with diversity and convenience.

2. Drug carriers

For medical products, extrusion through nanoporous polymer filters is used to produce suspensions of lipid vesicle liposomes or transporters with narrow size distribution. The anticancer drug adriamycin, such as liposomes in liposome delivery systems, is prepared by extrusion.

Hot melt extrusion is also used for oral dosage processing of drug solids to achieve the delivery of drugs with poor solubility and bioavailability. Hot melt extrusion has been proved to disperse insoluble drug molecules in polymer carriers, thus improving dissolution and bioavailability. This process involves the application of heat, pressure and stirring to mix materials together and "squeeze" them through a die.

The twin-screw high-shear extruder mixes materials and breaks particles at the same time. The obtained granules can be mixed with compression AIDS and compressed into tablets or filled into unit dose capsules.

3. Biomass briquette

Fuel briquetting extrusion technology is a process of extruding screw waste (straw, sunflower seed shell, buckwheat, etc.). ) or fine wood waste (sawdust) at the high temperature of 160 ~ 350℃. The obtained fuel block does not contain any binder, but contains natural lignin in plant waste cells. The temperature in the compression process will melt the surface of the brick and make it stronger, which is very important for the transportation of briquettes.

Refer to the above? Baidu encyclopedia-plastic extruder