The following is a detailed introduction to the molding processes of plastics and rubber. 

Plastic molding process 

Injection molding 

Injection molding 

Injection molding, also known as injection molding, works on the principle that granular or powdered raw materials are added to the hopper of an injection machine. The raw materials are heated and melted into a flowable state. Under the push of the screw or piston in the injection machine, they pass through the nozzle and the gating system of the mold and enter the mold cavity, where they harden and take shape. 

Process flow: 

The factors influencing the quality of injection molding: injection pressure, injection time, injection temperature. 

Process features: 

Advantages: 

Short molding cycle, high production efficiency, and easy to achieve automation. 

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

3. The product quality is stable. 

4. Wide range of adaptability 

Disadvantages:

1. The price of injection molding equipment is relatively high.

2. The structure of injection molds is complex.

3. The production cost is high, the production cycle is long, and it is not suitable for the production of single-piece and small-batch plastic parts. 

Application:

In industrial products, injection-molded items include: kitchenware (garbage cans, bowls, buckets, kettles, tableware and various containers), casings for electrical appliances (hair dryers, vacuum cleaners, food blenders, etc.), toys and games, various products in the automotive industry, and parts for many other products. 

2. Insert Molding 

Insert molding: Insert molding refers to a molding method where a pre-prepared insert of a different material is placed in a mold and then resin is injected. The molten material bonds with the insert and solidifies to form an integrated product. 

Process flow: 

In the insert molding process, the injection molding machine is usually only a part of the entire system. The inserts are typically oriented first, which can be accomplished using a vibrating table. Then, the inserts are placed into the mold by the end-of-arm tool (EOAT), often with the aid of a pre-positioning device to enter the mold. At the stage of the finished part, ejection positioning is the most crucial step, and the repeatability of the injection molding machine's mold opening action is of vital importance here. After being closed in the mold, the inserts are fixed either in a vacuum state or mechanically (such as by using sliders). As the inserts are inserted, the previous finished part is ejected. 

Technical features:

1. The pre-molding combination of multiple inserts makes the post-processing of product unit combination more rational.

2. The combination and complementation of the easy moldability and flexibility of resin with the rigidity, strength and heat resistance of metal can firmly produce complex and delicate metal-plastic integrated products.

3. Especially by taking advantage of the combination of the insulation of resin and the conductivity of metal, the molded products can meet the basic functions of electrical products.

4. For rigid molded products and flexible elastic molded products on rubber sealing gaskets, after being integrated into one product through injection molding on the base, the complex operation of arranging sealing rings can be omitted, making the automatic combination of the subsequent processes easier. 

3. Two-color injection molding 

Two-color injection molding: It refers to the molding method of injecting two plastics of different colors into the same mold. It can make the plastic appear in two different colors and enable the plastic part to present regular patterns or irregular cloud-like patterns, thereby enhancing the usability and aesthetic appeal of the plastic part. 

Technical features:

1. The core material can be made of low-viscosity materials to reduce injection pressure.

2. For environmental considerations, the core material can be made of recycled secondary materials.

3. Depending on different usage characteristics, such as using soft materials for the outer layer of thick products and hard materials for the core, or using foamed plastic for the core to reduce weight. 

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

5. The outer layer material or core material can use expensive materials with special surface properties, such as anti-electromagnetic interference and high electrical conductivity, to enhance product performance. 

6. Appropriate combination of skin and core materials can reduce residual stress in molded products, increase mechanical strength or improve surface properties of the products. 

4. Microcellular Injection Molding Process

The microcellular injection molding process is an innovative precision injection molding technology that fills the product by the expansion of gas pores and completes the molding of the part at a lower and more uniform pressure.

Basic principle:

The microcellular foaming molding process can be divided into three stages: First, a supercritical fluid (carbon dioxide or nitrogen) is dissolved into the molten polymer to form a single-phase solution; then, it is injected into the mold cavity at a lower temperature and pressure through a switchable nozzle. Due to the decrease in temperature and pressure, the instability of the molecules is triggered, resulting in the formation of numerous bubble nuclei in the product, which gradually grow to form tiny pores. 

Process features: 

Precision injection molding 

2. It has broken through many limitations of traditional injection molding, significantly reducing the weight of the parts and shortening the molding cycle. 

3. It has greatly improved the warpage deformation and dimensional stability of the molded parts. 

Application: 

Automobile instrument panels, door panels, air conditioning ducts, etc. 

5. Nano Molding Technology (NMT) 

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ZTE Grand S EXT 

NMT (Nano Molding Technology): It is a manufacturing method that combines metal and plastic through nanotechnology. First, the metal surface is treated at the nanometer level, and then plastic is directly injection molded onto the metal surface, allowing the metal and plastic to be formed as one. 

Nanomolding technology is classified into two types of processes based on the position of the plastic: 

The plastic is integrally molded for the non-visible surface. 

2. One-piece molding with plastic as the outer surface. 

Process features: 

The product has a metallic appearance and texture. 

2. The design of the product's structural components is simplified, making the product lighter, thinner, shorter and smaller, and it is more cost-effective than CNC machining. 

3. Reduce production costs, achieve high bonding strength, and significantly lower the usage rate of related consumables. 

Applicable metal and resin materials: 

Aluminum, magnesium, copper, stainless steel, titanium, iron, galvanized sheet, brass; 

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

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

4. PPS has an exceptionally strong bonding strength (3000N/c㎡). 

Application: 

Mobile phone cases, laptop cases, etc. 

Injection molding machine equipment supplier: 

HUSKY Company of Canada 

2. Japanese Toshiba injection molding machines 

3. Ube 

4. Toyo (Eastern) 

5. Engel Company, Austria 

6. LK Machinery 

……

Two Extrusion molding (profiles) 

Extrusion molding: also known as extrusion plastic molding, is mainly suitable for the molding of thermoplastic materials, and is also suitable for the molding of some thermosetting and reinforced plastics with good fluidity. The molding process involves using a rotating screw to extrude the heated and melted thermoplastic material through a die with the desired cross-sectional shape, then shaping it with a sizing die, and finally cooling it in a cooler to harden and solidify, resulting in a product with the desired cross-sectional shape. 

Process features: 

1. Low equipment cost; 

2. The operation is simple, the process is easy to control, and it is convenient to achieve continuous and automated production. 

3. High production efficiency; uniform and dense product quality. 

4. By changing the die at the head of the machine, products or semi-finished products of various cross-sectional shapes can be formed. 

Application: 

In the field of product design, extrusion molding has strong applicability. The types of products made by extrusion molding include pipes, films, rods, monofilaments, flat belts, nets, hollow containers, window and door frames, plates, cable sheaths, monofilaments, and other profiled materials. 

Extruder equipment supplier: 

German Coperion 

2. KraussmaffeiBerstorff of Germany 

3. German Battenfeld 

Three-roll calendering (sheet, film) 

Calendering: It is a method where plastic raw materials pass through a series of heated rollers, causing them to connect into films or sheets under the effects of extrusion and extension. 

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Rolling forming schematic diagram

Advantages:

Good product quality, large production capacity, and capable of continuous automated production;

Disadvantages:

Large equipment, high precision requirements, numerous auxiliary devices, and the width of the product is limited by the length of the rolling machine's rollers. 

Application:

It is mainly used in the production of PVC flexible films, thin plates, sheets, artificial leather, wallpaper, floor covering, etc. 

Rolling mill equipment suppliers:

1. Taiwan Xianggong Machinery Co., Ltd.

2. Wuxi Shuangxiang Rubber and Plastic Machinery Co., Ltd.

3. Dalian Huahan Rubber and Plastic Machinery Co., Ltd.

IV. Blow Molding

Blow molding: It is a method of taking the molten thermoplastic material extruded from an extruder, inserting it into a mold, and then blowing air into the material. Under the action of air pressure, the molten material expands and adheres to the mold cavity wall, and finally cools and solidifies into the desired product shape. 

Blow molding is divided into film blow molding and hollow blow molding.

1. Film blow molding

Film blow molding is a process where molten plastic is extruded from the annular gap of the die at the head of an extruder in the form of a cylindrical thin tube. At the same time, compressed air is blown into the inner cavity of the thin tube through the central hole of the die, causing the thin tube to expand into a larger diameter tubular film (commonly known as a bubble tube), which is then cooled and wound up.

2. Hollow blow molding

Hollow blow molding is a secondary forming technology that uses gas pressure to expand a preform in a rubber-like state, which is closed in the mold cavity, into a hollow product. It is a method for manufacturing hollow plastic products. Hollow blow molding can be classified into extrusion blow molding, injection blow molding, and stretch blow molding based on the different methods of preform manufacturing. 

1) Extrusion blow molding: In extrusion blow molding, a tube-shaped parison is extruded by an extruder. While still hot, it is clamped in the cavity of a mold and the bottom is sealed. Then, compressed air is introduced into the inner cavity of the tube parison to blow it up and form the product.

2) Injection blow molding: The parison is obtained by injection molding. The parison remains on the core mold of the mold. After the blow mold is closed, compressed air is introduced into the core mold to blow up the parison. After cooling, the product is demolded. 

Advantages:

Uniform wall thickness of the product, small weight tolerance, less post-processing, and minimal waste edges and corners; suitable for mass production of small, high-precision products. 

3) Stretch blow molding: A method where a preform that has been heated to the stretching temperature is placed in a blow molding mold, stretched longitudinally by a stretching rod, and expanded laterally by compressed air blown in, thereby obtaining the product. 

Application:

1. Film blowing is mainly used for manufacturing plastic thin films.

2. Hollow blowing is mainly used for making hollow plastic products (bottles, packaging drums, sprayers, fuel tanks, cans, toys, etc.).

Blow molding equipment suppliers:

1. France Sidel

2. Germany Krones 

V. Compression Molding

Compression molding is mainly used for the molding of thermosetting plastics. According to the properties of the molding materials and the characteristics of processing equipment and techniques, compression molding can be divided into two types: compression molding and laminating molding. 

Compression molding, also known as compression molding, is the main method for molding thermosetting plastics and reinforced plastics. The process involves placing raw materials in a mold that has been heated to a specified temperature and applying pressure to make the raw materials melt and flow uniformly to fill the mold cavity. Under the conditions of heating and pressure, the raw materials are transformed into products after a certain period of time. 

Features:

Molded products are dense in texture, precise in size, smooth and clean in appearance, free of gate marks, and have good stability.

Applications:

In industrial products, molded items include electrical equipment (plugs and sockets), pot handles, handles of tableware, bottle caps, toilet bowls, unbreakable dinner plates (melamine), carved plastic doors, etc. 

2. Laminating

Laminating: It is a method of combining two or more layers of the same or different materials into a single entity by using sheet or fiber materials as fillers under conditions of heating and pressure. 

Process flow: 

The laminating molding process consists of three stages: impregnation, pressing and post-processing. It is widely used in the production of reinforced plastic sheets, pipes, rods and model products, etc. 

Features: 

The texture is dense and the surface is smooth and glossy. 

Hot press forming machine equipment supplier: 

Toshiba of Japan 

2. Sacmi Group 

Six Injection Compression Molding

Injection compression molding: It is a molding method for thermosetting plastics developed on the basis of compression molding, also known as transfer molding. Its process is similar to that of injection molding. In injection compression molding, the plastic is plasticized in the feeding cavity of the mold and then enters the cavity through the gating system, while in injection molding, the plastic is plasticized in the barrel of the injection molding machine. 

Injection compression molding schematic diagram

The difference between injection compression molding and compression molding:

In the compression molding process, the material is added first and then the mold is closed, while in injection compression molding, it is generally required to close the mold first and then add the material. 

Process features:

Advantages (compared with compression molding):

1. The plastic is plasticized before entering the cavity, allowing for the production of complex-shaped, thin-walled or thick-walled plastic parts with fine inserts.

2. Shortens the molding cycle, improves production efficiency, and enhances the density and strength of the plastic part.

3. As the mold is fully closed before plastic molding, the flash at the parting surface is very thin, making it easier to ensure the accuracy of the plastic part and resulting in a lower surface roughness. 

Disadvantages:

1. There is always a portion of leftover material remaining in the feeding chamber, resulting in a relatively high consumption of raw materials.

2. The trimming of gate marks increases the workload.

3. The molding pressure is higher than that of compression molding, and the shrinkage rate is also greater.

4. The structure of the mold is more complex than that of compression molds.

5. The process conditions are more stringent than those of compression molding, and the operation is more difficult. 

Suppliers of hydraulic forming machine equipment:

1. Dongguan Guocheng Precision Hydraulic Machinery Manufacturing Co., Ltd.

2. Quanzhou Lianda Municipal Machinery Manufacturing Co., Ltd.

3. Henan Machinery Design & Research Institute Co., Ltd. 

VII. Rotational Molding

Rotational molding: Firstly, plastic raw materials are added into the mold. Then, the mold is continuously rotated along two perpendicular axes and heated. Under the influence of gravity and thermal energy, the plastic raw materials inside the mold gradually and evenly coat and melt to adhere to the entire surface of the mold cavity, forming the desired shape. After cooling and setting, the mold is opened, and the final product is obtained. 

Advantages:

1. Provides more design space and reduces assembly costs.

2. Simple to modify and low cost.

3. Saves raw materials. 

Applications:

Water polo balls, float balls, small swimming pools, bicycle seat cushions, surfboards, machine casings, protective covers, lampshades, agricultural sprayers, furniture, canoes, camping vehicle tops, etc. 

Rotomolding machine equipment suppliers:

1. Wenling Xuri Rotomolding Technology Co., Ltd.

2. Zhejiang Anji Tianyang Rotomolding Equipment Co., Ltd. 

Droplet molding: It takes advantage of the property of thermoplastic polymers that they can change states, meaning they have a viscous flow under certain conditions and can return to a solid state at room temperature. This process involves using appropriate methods and specialized tools to spray ink.