(I) Injection molding
Injection Molding: the process of injection molding begins by adding raw materials granular or powdered into a hopper of an injection machine and heating and melting into a flowing state by means of screw or piston action, ultimately entering mold cavities through their pouring systems to harden into shape over time and harden once set within them. Factors which determine its quality of injection are pressure, time and temperature for molding processes.
Process characteristics:
Advantages:
1. Short molding cycle, high production efficiency, easy to automate
2. Capable of forming plastic parts with complex shapes, precise dimensions, and metal or non-metal inserts
3. Stable product quality
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. High production costs, long production cycles, and unsuitable for single-piece small-batch plastic production
Application:
In industrial products, injection molded products include kitchen supplies (trash cans, bowls, buckets, pots, tableware, and various containers), housings for electrical equipment (hair dryers, vacuum cleaners, food mixers, etc.), toys and games, various products for the automotive industry, and parts for many other products.
(II) Insert injection molding
Insert Molding: Insert molding is a molding process in which preformed inserts of another material are placed within a mold and then filled with resin that bonds them securely, ultimately producing an integrated product.
Process characteristics:
1. The pre-molding combination of multiple inserts makes the post-engineering of product unit combinations more rationalized.
2. The combination of the ease of molding and flexibility of resin with the rigidity, strength, and heat resistance of metal can be used to create complex and sophisticated metal-plastic integrated products that are strong and durable.
3. In particular, the combination of the insulating properties of resin and the conductive properties of metal is utilized to produce molded products that can meet the basic functions of electrical products.
4. For rigid molded products and curved elastic molded products on rubber sealing gaskets, after being integrated into a product through injection molding on the substrate, the complex operation of arranging sealing rings can be eliminated, making it easier to automate the assembly of subsequent processes.
(III) Two-color injection molding
Two-color injection molding: refers to the process of injecting two different colors of plastic into one mold simultaneously, creating multiple plastic parts with distinctive hues or cloudlike patterns, to enhance usability and aesthetics of their plastic parts.
Process characteristics:
1. The core material can use low viscosity materials to reduce the injection pressure.
2. For environmental protection, recycled secondary materials can be used as core materials.
3. According to different usage characteristics, such as using soft materials for thick finished leather layers and using hard materials for core materials, or using foamed plastic for core materials to reduce weight.
4. Lower quality core materials can be used to reduce costs.
5. The cortical material or core material can be made of expensive materials with special surface properties, such as electromagnetic interference resistance and high electrical conductivity, to enhance product performance.
6. Proper combination of cortical and core materials can reduce residual stress in molded products, increase mechanical strength, or improve product surface properties.
(IV) Microfoaming injection molding process
Microcellular foaming injection molding process: It is a revolutionary precision injection molding technology that relies on the expansion of pores to fill the product and complete the molding of the part under low and average pressure. The microcellular foaming molding process can be divided into three stages: first, supercritical fluid (carbon dioxide or nitrogen) is dissolved into hot melt adhesive to form a single-phase solution; then, a switch-type nozzle is used to inject the mold cavity with low temperature and pressure, which causes molecular instability due to the decrease in temperature and pressure, resulting in the formation of a large number of bubble nuclei in the product. These bubble nuclei gradually grow to form tiny holes.
Process characteristics:
1. Precision injection molding;
2. It breaks through many limitations of traditional injection molding, significantly reducing the weight of the parts and shortening the molding cycle;
3. Greatly improve the warpage and dimensional stability of the parts.
Application:
Automobile dashboard, door panel, air conditioning duct, etc
(V) Nano-Injection Molding (NMT)
NMT (NanoMoldingTechnology): Nano MoldingTechnology is an emerging method for joining metal and plastic using nanotechnology. First, metal surfaces are treated with nanotech, followed by plastic being directly injected and molded over it to form one piece containing both materials. Nano molding technology can be broken into two processes depending on the location of the plastic:
1. Plastic is integrally molded for non-appearance surfaces
2. Plastic is integrally formed for the appearance surface
Process characteristics:
1. The product has a metallic appearance and texture,
2. The design of the product’s structural components is simplified, resulting in a lighter, thinner, shorter, and smaller product, and is more cost-effective than CNC machining methods.
3. Reduce production costs and high bonding strength, and significantly reduce the usage rate of related consumables
Applicable metal and resin materials:
1. Aluminum, magnesium, copper, stainless steel, titanium, iron, galvanized sheet, brass;
2. Resins include PPS, PBT, PA6, PA66, PPA;
Aluminum alloy has strong adaptability, including 1000 to 7000 series;
PPS has a particularly strong adhesive strength (3000N/c㎡).
Application:
Mobile phone shell, laptop shell, etc