（1） Injection molding

Injection molding: Also known as injection molding, its principle is to add granular or powdery raw materials to the hopper of the injection molding machine. The raw materials are heated and melted into a flowing state. Driven by the screw or piston of the injection molding machine, they enter the mold cavity through the nozzle and the mold pouring system, and harden and shape in the mold cavity. Factors that affect the quality of injection molding: injection pressure, injection time, and injection temperature.

Process characteristics:

advantage:

1. Short molding cycle, high production efficiency, and easy automation

2. Capable of forming plastic parts with complex shapes, precise dimensions, and metal or non-metallic inserts

3. Stable product quality

4. Wide range of adaptation

Disadvantages:

1. Injection molding equipment is expensive

2. Complex structure of injection mold

3. High production cost, long production cycle, not suitable for single small batch plastic parts production

Application:

Among industrial products, injection molded products include kitchen supplies (trash cans, bowls, buckets, pots, cutlery, and various containers), electrical equipment casings (hair dryers, vacuum cleaners, food mixers, etc.), toys and games, various products from the automotive industry, and parts for many other products.

（2） Insert injection molding

Insert molding: Insert molding refers to the molding process of filling a mold with pre prepared inserts of different materials, injecting resin, and bonding and curing the melted material with the insert to produce an integrated product.

Process characteristics:

1. The pre molding combination of multiple inserts makes the post engineering of product unit combinations more reasonable.

2. The combination of resin's easy formability, flexibility, and metal's rigidity, strength, and heat resistance complements the robust production of complex and delicate metal plastic integrated products.

3. In particular, the combination of resin insulation and metal conductivity is utilized to make molded products that meet the basic functions of electrical products.

4. For rigid molded products and bending elastic molded products on rubber sealing pads, the complex operation of arranging sealing rings can be eliminated by injection molding on the substrate to produce integrated products, making the automatic combination of subsequent processes easier.

（3） Dual color injection molding

Two color injection molding: refers to the molding method of injecting two kinds of plastics with different colors into the same mold. It can make plastic appear in two different colors, and can make plastic parts present regular patterns or irregular moire patterns to improve the usability and aesthetics of plastic parts.

Process characteristics:

1. The core material can use a low viscosity material to reduce the injection pressure.

2. From the perspective of environmental protection, recycled secondary materials can be used for core materials.

3. According to different usage characteristics, such as using soft materials for the thick finished product skin material, using hard materials for the core material, or using foam plastics for the core material to reduce weight.

4. Lower quality core materials can be utilized to reduce costs.

5. The use of expensive materials with special surface properties such as anti electromagnetic interference, high conductivity, and other materials for the skin or core materials can increase product performance.

6. Proper blending of the core material with the skin material can reduce residual stress in the molded product, increase mechanical strength, or increase surface properties of the product.

（4） Micro foam injection molding process

Microfoam injection molding process: It is an innovative precision injection molding technology that relies on the expansion of air holes to fill the product and complete the molding of the product under low and average pressure. The microcellular foaming process can be divided into three stages: first, dissolving supercritical fluid (carbon dioxide or nitrogen) into a hot melt adhesive to form a single-phase solution; Then, a switch type nozzle is used to shoot into the mold cavity with low temperature and pressure. Due to the molecular instability caused by the decrease in temperature and pressure, a large number of bubble nuclei are formed in the product, and these bubble nuclei gradually grow to form small holes.

Process characteristics:

1. Precision injection molding;

2. Breaking through many limitations of traditional injection molding, it can significantly reduce the weight of the workpiece and shorten the molding cycle;

3. Greatly improves the warpage deformation and dimensional stability of the workpiece.

Application:

Automobile instrument panel, door panel, air conditioning duct, etc

（5） Nano injection molding (NMT)

NMT (NanoMolding Technology): It is a process that combines metal and plastic using nanotechnology. After the metal surface is subjected to nanotechnology treatment, the plastic is directly injected and molded onto the metal surface, allowing the metal and plastic to be integrally formed. Nanoforming technology is divided into two types of processes based on the location of the plastic:

1. The plastic is integrally molded with a non appearance surface

2. Plastic is integrally molded for appearance

Process characteristics:

1. The product has a metallic appearance texture,

2. Simplify the design of product mechanisms, making products lighter, thinner, shorter, and smaller, and more cost-effective than CNC machining methods.

3. Reduce production costs and high bonding strength, and significantly reduce the utilization rate of related consumables

Suitable metal and resin materials:

1. Aluminum, magnesium, copper, stainless steel, titanium, iron, galvanized plate, brass;

2. Aluminum alloys have strong adaptability, including 1000 to 7000 series;

3. Resins include PPS, PBT, PA6, PA66, and PPA;

4. PPS has a particularly strong adhesive strength (3000 N/c ㎡).

Application:

Mobile phone shell, notebook computer shell, etc

2、Blow molding

Blow molding: A method of clamping molten thermoplastic raw materials extruded from an extruder into a mold, then blowing air into the raw materials. The molten raw materials expand under the action of air pressure, adhere to the wall of the mold cavity, and finally cool and solidify into the desired product shape. There are two types of blow molding: film blow molding and hollow blow molding:

1. Film blow molding

Film blow molding is the process of extruding molten plastic into a cylindrical thin tube from the annular gap of the die of the extruder head, while blowing compressed air from the center hole of the head into the inner cavity of the thin tube, expanding the thin tube into a larger diameter tubular film (commonly known as a bubble tube), and cooling it before coiling.

2. Hollow blow molding

Hollow blow molding is a secondary molding technology that uses gas pressure to inflate the rubber like preform closed in the mold cavity into hollow products. It is a method for producing hollow plastic products. According to the manufacturing methods of parison, hollow blow molding includes extrusion blow molding, injection blow molding, and stretch blow molding.

1) Extrusion blow molding: Extrusion blow molding is the process of using an extruder to extrude a tubular preform, clamp it in the mold cavity while it is hot and seal it, and then inject compressed air into the inner cavity of the tube preform for blow molding.

2) Injection blow molding: The parison used is obtained by injection molding. The parison is left on the core mold of the mold, and after being closed with a blow molding mold, compressed air is introduced from the core mold to inflate, cool, and demould the parison to obtain the product.

advantage:

The product has uniform wall thickness, small weight tolerance, less post processing, and small scrap corners; Suitable for producing small precision products in large batches.

3) Stretch blow molding: A method of obtaining a product by placing a parison that has been heated to a stretching temperature in a blow molding mold, using a stretching rod for longitudinal stretching, and using blown compressed air for lateral stretching and blowing.

Application:

1. Film blow molding is mainly used for manufacturing thin plastic molds;

2. Hollow blow molding is mainly used to produce hollow plastic products (bottles, packaging barrels, watering cans, fuel tanks, cans, toys, etc.).

3、 Extrusion molding (profiles)

Extrusion molding: Also known as extrusion molding, it is mainly suitable for the molding of thermoplastics, as well as some thermosetting and reinforced plastics with good fluidity. The molding process is to use a rotating screw to extrude the thermoplastic raw material that has been heated and melted from the machine head with the desired cross-sectional shape, then shape it with a molding machine, and then cool and harden it through a cooler to become a product with the desired cross-sectional shape.

Process characteristics:

1. Low equipment cost;

2. Simple operation, easy control of the process, and easy to achieve continuous automated production;

3. High production efficiency; Product quality is uniform and dense;

4. Products or semi-finished products with various cross-sectional shapes can be formed by changing the die of the machine head.

Application:

In the field of product design, extrusion molding has strong applicability. The types of extruded products include pipes, films, rods, monofilament, flat tapes, nets, hollow containers, windows, door frames, plates, cable cladding, monofilament, and other profiled materials.