Injection Molding Process
Refers to Injection Molds and Plastic Injection Molding Products
The injection molding process in the china，process produces large numbers of parts of high quality，great accuracy, quickly cycle time. The production of plastic injection molds from both thermoplastic and thermosetting plastic materials. The plastic material, in the form of particles, is melted until it is soft enough to be injected under pressure, either through a reciprocating screw or a ram ejector, into the mold cavity. In China, when a part is designed from the customer, then manufacturing molds by an injection mold company, it needs a mold maker (or toolmaker) team to build. The result is that the shape is exactly copied. Once the plastic injection molding has cooled sufficiently to harden the mould opens releasing the part. The whole injection moulding process then repeats.
Injection molds making in China, we usually manufactured using steel or aluminum, and precision-machined to form the features of the desired parts. Injection molding is widely used for manufacturing a variety of parts, including household appliances, consumer electronics, power tools, and automotive dashboards. Other common thin-walled products include different types of open containers, such as buckets. Injection molding is also used to produce several everyday items such as toothbrushes or small plastic toys. Many medical devices, including valves and syringes, are manufactured using injection molding as well.
Injection Mold situation in China
China’s rapid economic development of the tooling industry put forward higher requirements, but also for its development has provided the great impetus. In the past 10 years, China’s mold industry has been rapid development of about 15 % per year growth rate. In recent years, the mold industry to accelerate the pace of structural adjustment , mainly for large , sophisticated, complex, long-life mold standard parts, standard mold growth rate higher than the overall growth rate of the industry; larger proportion of plastic and Die-casting mold ; Despite the development of China ‘s mold industry, there is an imbalance in the geographical distribution of the mold industry， The most concentrated area of mould production is pearl river delta and Yangtze river delta, which accounts for over two-thirds of the country mold output value.
China’s market leader Dies, Shanghai is China’s leading injection molds market today is China’s largest export mold city. 40% of the value of the multinational mold from Shanghai, and the performance rate of NC mold processing equipment and equipment, mold processing technology, the degree of specialization in production levels and standards ahead of other provinces. With further optimization of industrial structure, develop IT, automotive, high-tech and other industries are Shanghai mold manufacturing to higher requirements. Next few years, Shanghai mold manufacturing will become increasingly sophisticated, complex. Private companies such as CNMOULDING growth rate of 100 %, become an important member of the china injection mold industry.
Applications of China Injection Molds
Plastic Injection molding in China is the most commonly used manufacturing process for the fabrication of plastic parts. A wide variety of products are manufactured using injection molding, which varies greatly in their size, complexity, and application. The plastic injection molding process requires the use of an injection molding machine, raw plastic material, and a mold. The plastic is melted in the injection molding machine and then injected into the mold, where it cools and solidifies into the final part. The steps in this process are described in greater detail in the next section a popular material for Injection Molds
IMPORTANT: Information below is a general materials description overview, and is intended for preliminary material identification ONLY.
China Plastic Injection Molding Machine-Injection Molding Process
Injection molding machines, also known as presses, consist of a material hopper, an injection ram or screw-type plunger, and a heating unit. The molds are clamped to the platen of the molding machine, where plastic is injected through the sprue orifice to create injection molds.
Here we especially introduce a high-speed injection molding machine in China.
1.High-speed injection molding machine Clamping Unit
The new generation toggle mold locking device and computer emulation optimized toggle parameter makes motions of the moving plate fast and steady.
2.High-speed injection molding machine Hydraulic Unit
High efficiency, energy-saving and high precise proportional pressure and flow variable displacement pump system makes the hydraulic system output match the required power for entire machine operation without high-pressure throttle and overflow energy loss.
3.High-speed injection molding machine Injection Unit
The short and forceful double-cylinder injection system is used to ensure the stead injection motions. The strain-free fixed mold plate and screw assembly with optimized design help to reach better plasticating capacity and effect.
4.High-speed injection molding machine Control Unit
The high-performance special control for injection molding machines. Switch of Chinese and English, clear and visual, and easy operation.
Mold making in China
Mold is the common term used to describe the tooling used to produce injection molded plastic parts.
It is mainly the production of thermoplastic products the most common kind of mold, plastic injection mold processing equipment for the plastics injection molding machine, plastic melt first heat in the heated barrel of the end of the injection machine, and then injection molding machine into the mold cavity under the impetus of a screw or a plunger, the injection machine nozzle and mold casting system, plastic cooling hardening molding, mold release to get the products. Its structure is usually molded parts, casting systems, parts-oriented components, the introduction of institutions, thermostat systems, exhaust systems, and support components.
Manufacturing materials commonly used plastic mold steel modules, commonly used material is mainly carbon structural steel, carbon tool steel, alloy tool steel, high-speed steel. Injection molding process usually applies only to the varieties of products, production of thermoplastic injection molding process to produce plastic products is very extensive, from the daily necessities of life to all kinds of complex mechanical, electrical, transport parts are injection molding, it is the most widely used in the production of plastics processing methods.
Custom Mold Design – Injection Molds
Molds consist of two primary halves, injection molds (A plate) and ejector molds (B plate). First, plastic resin enters the mold through a sprue in the injection mold. The sprue bushing is to seal tightly against the nozzle of the injection barrel of the molding machine in order to allow molten plastic to flow from the barrel into the mold, also known as a cavity. The sprue bushing directs the molten plastic to the cavity images through channels that are machined into the faces of the A and B plates. These channels allow the plastic to run along with them, so they are referred to as runners. The molten plastic flows through the runner and enters one or more specialized gates and into the cavity geometry to form the desired injection molded part.
According to the size of the production capacity, product structure, to determine the appropriate number of cavities, more precision molds, processing difficulty, the higher the cost of the mold cavity. However, the unit price of injection molded parts dropped significantly.
Factors that affect the size of the multi-cavity:
1, Precision injection mold processing. Such as cavity discharge, each chamber is a discharge, the discharge process is not well controlled, cavity size deviation.
2, The injection mold assembly precision. Because of the reasons of the assembly results in the internal structure of position deviation.
3, Injection mold design factors, such as whether the design of the flow channel and reasonable uniformity into the plastic, unreasonable runner advanced gum near the nozzle chamber, away from the last-glue because of contraction inconsistent, holding pressure situation size will also inconsistent deviation. Into the rubber mouth, the diameter size will cause the size of the deviation. Mold waterway design is unreasonable, in the cavity waterway layAccording to the size of the production capacity, product structure, to determine the appropriate number of cavities, more precision molds, processing difficulty, the higher the cost of the mold cavity. However, the unit price of injection molded parts dropped significantly.
Factors that affect the size of the multi-cavity:
1, Precision mold processing. Such as cavity discharge, each chamber is a discharge, the discharge process is not well controlled, cavity size deviation.
2, The mold assembly precision. Because of the reasons of the assembly results in the internal structure of position deviation.
3, Mold design factors, such as whether the design of the flow channel and reasonable uniformity into the plastic, unreasonable runner advanced gum near the nozzle chamber, away from the last-glue because of contraction inconsistent, holding pressure situation size will also inconsistent deviation. Into the rubber mouth, the diameter size will cause the size of the deviation. Mold waterway design is unreasonable, in the cavity waterway layout should be uniform cooling, if unreasonable, the different parts of the mold at different temperatures, resulting in shrinkage, and thus the size of the deviation. All in all, a multi-cavity mold size deviation basic mold. Little effect of the injection molding process.out should be uniform cooling, if unreasonable, the different parts of the mold at different temperatures, resulting in shrinkage, and thus the size of the deviation. All in all, a multi-cavity mold size deviation basic mold. Little effect of the injection molding process. According to the size of the production capacity, product structure, to determine the appropriate number of cavities, more precision molds, processing difficulty, the higher the cost of the mold cavity. However, the unit price of injection molded parts dropped significantly.
Plastic injection mold cost and useful in China
High-quality plastic injection mold includes a fast running cycle, long mold life, easy maintenance, and safety operation. The mold design, mold material, mold tooling machines, and mould assembling is very important to make a high-quality injection mold Usually customers would have doubt why for the same mold, different supplier quoted a different price, some even have a big difference. For mold manufacturers in china, offer an inquiry, engineers will check the mold structure according to the original sample pictures or drawing estimate the mold size, mold ejection method, injection gate, and so on. After we got the above information, we could calculate the mold cost according to the customer’s requirement.
Mold cost includes mould material cost, mold design cost, mold tooling cost, managing cost, and after-sales service cost. We suggest using good steel material for a high quantity requirement mold. If the mold structure is complex, we need to consider more carefully for the mould tooling. With high-quality injection molds, the mould could run a long time, and it is easier for mold maintenance. The production efficiency is much higher with continuously manufacturing. We suggest doing not only compare the mold price when investing in a new mold. Because after the mold running in a customer’s factory, but it would also affect working much. injection mold cost estimate, the Mold price difference in China, high-quality injection molds, high-efficiency molding line, famous mould supplier China, mold after-sales service The length of time from closing the mould to ejecting the finished plastic moulding is the cycle.
The size of an injection molded part will depend on a number of factors (material, wall thickness, shape, process, etc). The initial raw material required may be measured in the form of granules, pellets, or powders. Here are some ranges of sizes.
CNC-EDM-WIRE CUT MACHINE-Injection Molding Process
Injection Mold Companies use three main methods to manufacture molds: CNC number control milling machining and EDM, Wire cut machine… With technological development, CNC machining became the predominant means of making more complex molds with more accurate mold details in less time than traditional methods. Computer numeric controlled machining centers are used to produce a wide range of components, and tooling costs involved have continued to become more affordable. In general, large production runs requiring relatively simple designs are better served by other methods, although CNC machining can now accommodate a wide range of manufacturing needs. CNC milling centers are ideal solutions，everything ranging from prototyping and short-run production of complex parts，the the fabrication of unique precision components.
The basic EDM process is really quite simple.
An electrical spark is created between an electrode and a workpiece. Electric Discharge MachiningThe spark is visible evidence of the flow of electricity. This electric spark produces intense heat with temperatures reaching 8000 to 12000 degrees Celsius, melting almost anything. The spark is very carefully controlled and localized so that it only affects the surface of the material. The EDM process usually does not affect the heat treat below the surface. With wire EDM the spark always takes place in the dielectric of deionized water. The conductivity of the water is carefully controlled making an excellent environment for the EDM process. The water acts as a coolant and flushes away the eroded metal particles.
WIRE CUT MACHINE
Wire cutting uses a metallic wire to cut a programmed contour in a workpiece. Extrusion dies and blanking punches are very often machined by wire cutting. Cutting is always through the entire workpiece. To start machining it is first necessary to drill a hole in the workpiece or start from the edge. In the machining area, each discharge creates a crater in the workpiece and an impact on the tool. The wire can be inclined, thus making it possible to make parts with taper or with different profiles at the top and bottom. There is never any mechanical contact between the electrode and the workpiece (see above). The wire is usually made of brass or stratified copper and is between 0.1 and 0.3 mm in diameter.
Difference Producing Injection Molds Process in China
Fusible(lost, soluble)core injection molding
Gas-assisted injection molding
In-mold decoration and in-mold lamination
Insert and outsert molding
Lamellar (microlayer) injection molding
Low-pressure injection molding
Multicomponent injection molding(overmolding)
Multiple live-feed injection molding
Powder injection molding
Push-Pull injection molding
Reaction injection molding
Resin transfer molding
Structural foam injection molding
Structural reaction injection molding
Vibration gas injection molding
Water-assisted injection molding
Injection molding of liquid silicone rubber
Injection molding is a cyclic operation. The cycle consists of
• Mould close and clamp, (few seconds -depends on machine speeds)
• Injection – Fill (speed) phase, (few seconds) Switchover and Pack (pressure) phase,(few seconds)
• Cooling time, (40 to 60% of cycle time)
In China for a new mold test, an injection molding company technician operator usually starts with a small shot weight and fills gradually until the mold is 95 to 99% full. Once this is achieved a small amount of holding pressure will be applied and holding time increased until gate freeze off (solidification time) has occurred on the injection molded part. Gate solidification time is important as it determines cycle time, which itself is an important issue in the economics of the production process. Holding pressure is increased until the parts are free of sinks and part weight has been achieved. Once the parts are good enough and have passed any specific criteria, a setting date-sheet is produced for the customer to follow its produce.
We make thousands of plastic molds for our customers, but injection molding is a complex technology with possible production problems. They can either be caused by defects in the molds or more often by injection molded part processing (molding).—following date sheet learns from our American same trade from the internet.
Tolerances and Surfaces
Precision plastic mold processing machine is not selected as the achievable accuracy is not the same, and now the CNC, 0.002MM, EDM, 0.01MM wire walking 0.005MM, hand milling 0.02MM, drilling 0.05MM, grinders 0.005MM, Turning 0.01MM, each is different, you have to question what is it which machining accuracy? Chinese professional mold company can machine precision molds
The temperature of the mold plastic molding directly affects production efficiency and quality. The temperature is generally in the plastic are required about 200 ○ C by an injection machine nozzle to the mold injecting the melt in the mold about 60 ○ C curing, stripping, the heat radiation except for a few, other than the flowing atmosphere, a large part of the cooling water is introduced into the mold to take.ABS required mold temperature is low ( less than 80 ○ C), and therefore only needs to set the mold cooling system.
1.1 The importance of the mold temperature adjustment
1.1.1 The mold temperature and regulation systems for plastic parts quality. Mold temperature stability, the uniform cooling rate can reduce the volatility of plastic mold shrinkage is the reduction of plastic deformation of the fundamental conditions to ensure dimensional stability.
1.1.2 The mold temperature and regulation systems for production efficiency. According to the experimental results show that the injection molding of plastic melt in a stable injection temperature of 200 ○ C reduced 60 ○ C. The heat released is in the 5% radiation convection emitted to the atmosphere, and the remaining 95% the heat is taken away by the cooling medium ( water). The mold cooling time in general throughout the injection cycle of approximately 2 /3, showing the injection mold production efficiency mainly depends on the cooling time.
1.2 Calculation of the cooling system
Plastic passed to heat the mold
According to the formula : Q = nmq
Wherein Q- unit time to pass the plastic mold heat (kJ / h); n- number of injections per hour; m- injection amount of each plastic, including casting system (kg);
q- unit time of the plastic in the cavity the heat (kJ / kg), q value by the following formula to get : q = Cp (θ1-θ0) where : Cp- plastic heat capacity (kJ / kg · k) its check the value of “practical Mould Technology Handbook” table 12-3; θ1- filling plastic melt temperature (○ C); θ0- plastic mold temperature (○ C).
n = 3600/40 = 90
m = 0.051kg
Cp = 1.47 (kJ / kg · k)
θ1 = 200 ○ C
θ0 = 60 ○ C
Then Q = 90 × 0.051 × 1.47 × (200-60)
= 944.622 (kJ / h)
The heat removed by the cooling water.
According to the formula : Qw = 95% Q, Where: Qw- unit time within the mold cooling water away from the heat (kJ / h);
Q- unit time passed plastic mold heat (kJ / h).Then Qw = 0.95 × 463.05= 897.390 (KJ / h)
Heat transfer area ( cooling water table wall area).
According to the formula : Aw = Qw/3.6hwΔθ
Where: Aw- heat transfer area ( cooling water table wall area ) (m2);
how- cooling water wearing their wall heat transfer coefficient ;
Δθ- the average temperature of the mold cavity surface temperature of the cooling water is the difference between the average (○ C), wherein the cooling water temperature is the average of the cooling water inlet and outlet temperatures averaged.
hw = 2041 (1 +0.015 Qw-) V0.87/dw0.13
Where: DW- cooling channel diameter ( mm ) ;
V- cooling water flow rate (m / s);
Qw – the average temperature of the cooling water (○ C).
Qw = 439.9 (kJ / h)
hw = 2041 × (1 +0.015 × 40) × 1.660.87/80.13
= 2041 × 1.6 × 1.55 ÷ 1.31
Δθ = 10 (○ C)
Then Aw = 897.390 ÷ 3.6 ÷ 3863.9 ÷ 10
= 0.006 (m2)
14.2.4 The total length of the cooling water .
Lw = Aw / πdw
Where: Lw- cooling pipe total length.
Lw = 0.006 ÷ 3.14 ÷ 0.008
= 0.24 (m)
The calculated results show mold without the cooling pipe cooling. It is a thin-walled plastic part, so the mold cavity temperature is not very high, molded plastic parts can be cooled after themselves. But in order to shorten the molding cycle, improve production efficiency, the fixed template design mm diameter cooling channels, and put in the waterway diameter of 8 mm brass.