I. Injection molding
(I) Injection molding
Injection molding: also known as injection molding, its principle is to add the particle or powder raw material to the hopper of the injection machine, the raw material is heated and melted in a flow state, under the screw or piston of the injection machine, the injection system into the mold cavity, and hardened in the mold cavity. Factors affecting injection molding quality: injection pressure, injection molding time, and injection molding temperature
Process characteristics:
Benefits:
1, molding cycle is short, high production efficiency, easy to achieve automation
2, forms plastic components with complex shape, accurate size, with metallic or non-metallic inserts
3, product quality is stable
4, has a wide range of adaptations
Disadvantages:
1, injection molding equipment has high prices
2, injection molding mold has a complex structure
3, has high production cost, long production cycle and not suitable for single small batch of plastic parts
Application:
Among industrial products, injection molding products are: kitchen products (garbage cans, bowls, buckets, pots, tableware and various containers), shells of electrical equipment (hair dryers, vacuum cleaners, food mixer, etc.), toys and games, various products of the automobile industry, parts of many other products, etc.
(2) Injection molding of the inserts
insert injection molding: insertmolding (insertmolding) refers to the molding method of filling the prepared different material insert into the resin, combining the molten material and curing with the insert to make it into an integrated product.
Process characteristics:
1，The premolding combinations of multiple inserts of rationalize the post-engineering of product unit combinations.
2，The combination ofresin easy molding, bending and metal rigidity, strength and heat resistance can be made into complex and exquisite metal plastic integrated products.
3，In particular utilizes the combination of resin insulation and electrical conductivity of metal, and the molding products can meet the basic functions of electrical products.
4, For the rigid molding products and the curved elastic molding products on the rubber sealing pad, after making the integrated product through the injection molding on the base, it saves the complex operation of the sealing ring to be arranged, making the automatic combination of the later process easier.
(3) Two-color injection molding
Double color injection molding: refers to the molding method of injecting two different colors into the same mold. It can make the plastic appear in two different colors, and can make the plastic parts to present a regular pattern or irregular cloud pattern color, to improve the use and beauty of the plastic parts.
Process characteristics:
1, core material can use low-viscosity materials to reduce the ejection pressure.
2, from environmental protection considerations, the core material can use the recycled secondary material.
3, uses soft material according to different use properties, such as thick piece finished leather material, and the core material using hard material or core material can use foam plastic to reduce weight.
4, can utilize lower quality core materials to reduce costs.
5, cortex or core materials can be used with expensive and special surface properties such as electromagnetic wave interference and high conductivity to increase product performance.
6, Suitable leather and core combinations can reduce residual stress, increase mechanical strength or surface properties of the product.
(4) Micro-foaming injection molding process
Microfoam injection molding process: it is an innovative precision injection molding technology, filled by the expansion of the pores and completes the molding under low and average pressure. The microhole foaming process can be divided into three stages: first dissolve supercritical fluid (carbon dioxide or nitrogen gas) into hot melt glue to form a single phase solvent; then shoot the low temperature and pressure, because the temperature and pressure cause molecular instability to form a large number of bubble cores in the product, which gradually grow to produce small holes.
Process characteristics:
1, precision injection molding;
2, breaks through the many limitations of traditional injection molding, which can significantly reduce the weight of the manufacturing parts and shorten the molding cycle;
3, greatly improves the warp deformation and size stability of the components.
Application:
Car instrument panel, door panel, air conditioning air duct, etc
(V) Nanometer injection molding (NMT)
NMT (Nano Molding Technology): It is a method of metal combined with plastic by nanotechnology. After the metal surface is nano, the plastic directly shoots on the metal surface, so that the metal and plastic can be formed in one. Nanoforming technology is divided into two types of processes according to the location of the plastic:
1, plastic is a non-exterior surface of the integral molding
2, plastic is integrated for the exterior surface
Process characteristics:
1, products have a metallic exterior texture,
2, product mechanism parts design is simplified, making the products lighter, thinner, shorter and smaller, and more cost-effective than the CNC processing method.
3, reduces production costs, has high binding strength, and significantly reduces the utilization of related consumables
Applicable metal and resin materials:
1, aluminum, magnesium, copper, stainless steel, titanium, iron, galvanized plate, brass;
2, aluminum alloy is more adaptable, including 1000 to 7000 series;
3, resins include the PPS, PBT, PA6, PA66, PPA;
4, PPS has a particularly strong bonding strength (3,000 N/c ㎡).
Application:
Mobile phone shell, laptop case, etc
Second, blow-blown plastic molding
Blowing molding: it is the method that clips the molten thermoplastic raw material squeezed from the extruder into the mold, and then blows the air into the raw material. The molten raw material expands under the action of air pressure, fits to the mold cavity wall, and finally cooling and curing becomes the required product shape. Blow plastic molding is divided into two kinds of thin film blowing molding and hollow blow molding:
1, thin film blow molding
Film blowing plastic is to extrude the molten plastic from the cylindrical thin tube in the annular gap of the extruder head mold, while blowing the compressed air from the central hole of the head into the inner cavity of the thin tube, blowing the thin tube into a larger diameter tube film (commonly known as the bubble tube), and roll it after cooling.
2, Hollow blow molding
Hollow blow molding is the secondary molding technique of blowing the rubber-like billet closed in the mold cavity into hollow products, which is the method of producing hollow plastic products. Hollow blow molding is different according to the billet, including extrusion blow molding, injection blow molding and stretching blow molding.
1) Extrusion blow molding: Extrusion blow molding is an extruder extrusion of the tubular billet, while hot in the mold cavity and seal the bottom, and then to the tube cavity into the compressed air blowing molding.
2) injection: The blank used is formed by injection. The blank is left on the core die of the mold. After closing the mold, inject compressed air from the core die, blow and cool the products after stripping.
Benefits:
Wall thickness is uniform, small weight tolerance, less post-processing, and small waste corners; suitable for producing small batch of fine products.
3) Tensile blow molding: Place the billet that has been heated to the tensile temperature in the blowing molding mold, stretch vertically with the tensile rod, and blow horizontally with the blown compressed air, thus obtaining the product method.
Application:
1, film blow molding is mainly used in manufacturing plastic thin mold;
2, is mainly used for making hollow plastic products (bottles, packaging barrels, spray pots, fuel tanks, tanks, toys, etc.).
III. Extrusion molding (profile)
Extruded molding: also known as extruded molding, mainly suitable for thermoplastic molding, but also suitable for some better liquid thermosetting and reinforced plastic molding. The forming process is to use the rotating screw, squeeze the thermoplastic raw material heated and melted out from the nose with the desired section shape, and then shaped by the stereotype, and then cold and hard solidified through the cooler, become the product of the required section.
Process characteristics:
1, equipment cost;
2, has simple operation, easy process control and easy to achieve continuous automatic production;
3, has high production efficiency; the product quality is uniform and dense;
4, shapes various product or semi-finished products by changing the nose mold.
Application:
In the field of product design, extrusion molding has a strong applicability. The types of extrusion products are pipes, film, rod, single filament, flat strip, mesh, hollow containers, windows, door frames, plates, cable coating, single filament and other different profiles.
IV. Deferred forming (sheet material, thin film)
Extension forming: It is a method of plastic raw material connected into a film or sheet through a series of heated rollers under extrusion and extension.
Process characteristics:
Advantages: good product quality, large production capacity, automatic and continuous production;
Disadvantages: large equipment, high precision requirements, many auxiliary equipment and product width are limited by the roller length of the press.
Application:
Mainly used in the production of PVC soft film, thin plate, sheet material, artificial leather, wallpaper, floor leather, etc.
V. Press and forming
Suppression molding: mainly used for thermosetting plastic, according to the characteristics of forming material and process characteristics, pressing molding can be divided into processing equipment and technology.
1, die molding
Die molding, also known as compression molding, is the main method of thermosetting plastic and reinforced plastic molding. The process is to pressurize the raw material in the mold that has been heated to the specified temperature, so that the raw material can melt and flow and evenly filled with the mold cavity, after a certain time under the condition of heating and pressure, enabling the raw material to form the product.
Process characteristics:
Molded molding products have compact texture, accurate size, smooth appearance, no pouring marks and good stability.
Application:
In industrial products, the molded products are electrical equipment (plugs and sockets), pot handle, tableware handle, bottle cap, toilet device, non-broken dishes (petri dishes), carved plastic doors, etc.
2, laminated molding
Laminated forming: It is a method of combining a sheet or fiber material as a filler with the same or different material as a whole under heating or pressurized conditions.
Process characteristics:
The laminate forming process consists of three stages: impregnation, pressing and post-processing treatment, which is mostly used to produce reinforced plastic sheets, pipes, rods and model products. Compact texture and smooth surface.
VI. Injection molding
Injection molding: it is a thermosetting plastic molding method developed based on compression molding, also known as transfer molding. The process is similar to the injection molding process. During the injection molding, the plastic is molded in the feeding cavity of the mold, and then enters the type cavity through the pouring system, and the injection molding is molded in the material cylinder of the injection molding machine. The difference between compression molding and compression molding: compression molding process is the first adding before closing molding, while compression molding is generally closed first before adding.
Process characteristics:
Advantages: (as compared to compression molding)
1, plastic has been moulded before entering the cavity, producing plastics with complex shape, thin or wall thickness changes and with fine inserts.
2, shortens the molding cycle, improves the production efficiency, and improves the plastic parts density and strength.
3, Because the mold is completely closed before the plastic molding, the flying edge of the parting surface is very thin, so the accuracy of the plastic parts is easy to ensure a low surface roughness.
Disadvantages:
1, will always have a part of the surplus material left in the feeding room, the raw material consumption is large;
The repair of 2, pouring traces increases the workload;
3, molding pressure is greater than compression molding; shrinkage rate is greater than compression molding;
4，The structure of the mold is also more complex than that of the compression mold;
5, process conditions are more stringent than compression molding and difficult to operate.
VII. Rolling and plastic molding
Rolling molding: it is to add the plastic raw material to the mold, and then the mold constantly rotates along two vertical axes and heat it, so that the plastic raw material in the mold is gradually coated and melt evenly attached to the whole surface under the action of gravity and heat energy, attached to the whole surface of the mold cavity, forming into the required shape, and then through cooling, molding, and finally obtain the product.
Benefits:
1, provides more design space and reduces assembly costs;
2, changes is simple and low cost;
3, saves the raw materials.
Application:
Water polo, floating ball, small swimming pool, bike seat mats, surfboards, machine housing, shields, lampshade, farm sprayers, furniture, canoes, camping vehicle tops and more.
VIII. Drop-off plastic molding
Dropping molding: using the thermoplastic polymer material with variable state characteristics, that is, under certain conditions, and can restore the solid state characteristics at normal temperature, and use appropriate methods and special tools ink jet, in the design state, and then solidify at normal temperature. The process mainly includes three stages such as glue-drop plastic-cooling and curing
Benefits:
Good transparency and gloss of 1, products;
2, has physical characteristics such as anti-friction, waterproof, and pollution prevention;
3, has a unique stereoscopic effect.
Application:
Plastic gloves, balloons, condoms, etc
IX. Plastic absorption molding
Plastic suction molding: also called vacuum molding, is one of the thermoplastic thermoforming methods. It refers to the sheet or plate material clamped to the frame of the vacuum molding machine, after heating and softening, through the air channel of the mold, after a short time of cooling, to get the molded plastic products.
Process characteristics:
Vacuum forming method mainly includes concave mode vacuum molding, convex mode vacuum molding, vacuum molding successively, blowing bubble vacuum molding, plunger push down vacuum molding, vacuum forming with gas buffer device, etc.
Advantages:
The equipment is relatively simple, the mold does not need to bear the pressure, can be made of metal, wood or gypsum, fast molding speed, easy to operate.
Application:
It is widely used in the internal, outer packaging of food, cosmetics, electronics, hardware, toys, technology, medicine, health care products, daily necessities, stationery, disposable cups, various cups, etc.; breeding plates, seedling plates, biodegradable fast food boxes.
X. Enamel molding
Enamel: is the method of dumping the paste plastic (plastic solvent) into the mold (concave or Yin mold) heated to a certain temperature, the paste plastic near the mold cavity will gel due to heat, and then the paste plastic will be poured out, and the paste plastic attached to the inner wall of the mold cavity for heat treatment (baking), and then the hollow products can be obtained from the mold after cooling.
Process characteristics:
1, equipment costs are low, with a high production speed,
2, process control is simple, but the product thickness, quality (weight) quantity and accuracy are poor