Plastic Mould

Typically, the important factors when choosing plastic injection molding machine include mold, product, molding requirements and so on. Therefore, you must collect or have the following information before making a choice: mold dimension (width, height, thickness), weight and special design; types and amount of the plastic (single or multiple plastic materials); dimensions and weight of injection molding product (length, width, height, thickness); molding requirements, such as quality condition, production speed and so on.
In obtaining the above information, you can follow these steps to choose a suitable plastic injection molding machine:

Choose the right type of plastic injection molding machine: make decision by the products and plastic
The plastic injection molding machine has a lot of types, so at the beginning, you should determine that what kind or which series of plastic injection molding machine is fit for the product. For example, for thermoplastic plastic or Bakelite resin or PET, the product is single color, two-color, multi-color, laminated or blending. In addition, some product requires high stability (closed loop), high precision, high injection speed, high injection pressure and rapid production (multi-loop) and so on.
Good injection: plastic determine “screw compression ratio” and “injection pressure” and other conditions.
Some plastic requires a higher injection pressure and appropriate screw compression ratio for a good molding. So when choosing screw, it should considered about the demand of injection pressure and the problems of compression ratio. In general, smaller diameter screw provides higher injection pressure.

High injection speed: confirm the injection speed.
Some product requires a high injection speed to stabilize the injection molding, such as ultra-thin wall product. In this case, it is necessary to make sure that whether the injection speed and injection rate are enough or not, and whether accumulator and closed-loop control are necessary or not. Generally speaking, in the same condition, a screw in the plastic injection molding machine with high injection pressure has a lower injection speed, on the contrary, a screw with low injection pressure has a higher injection speed. So when choosing the screw diameter, injection volume, injection pressure, and injection rate (injection speed) should be cross considered.
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Able to put it on: the size of mold determine whether the internal spur of large column, the mold thickness, the minimum mold dimension and the mold plate size of plastic injection molding machine are suitable or not, to make sure that it is able to put mold on.
The mold width and height must be less than or at least less than the internal spur of large column; The mold width and height must in the mold plate size range; the mold thickness should be between the thickness of plastic injection molding machine; The mold width and height must be fit with the minimum mold size recommended by the plastic injection molding machine.

Able to put it out: the mold and product judge whether the “Opening Stroke” and “Ejector Stroke” are enough to remove the finished product.
The opening stroke should at least larger than the product height along the opening direction more than twice, including the length of vertical sprue; ejector stroke should long enough to eject the finished product.

Able to maintain locked: the product and plastic determine the tonnage of “clamping force”.
When the raw materials inject into the mold cavity in a high pressure, it will create a bulging force, so the clamping unit of the plastic injection molding machine should provide sufficient “clamping force” so that the mold was not subject to distraction. The need of clamping force is calculated as follows:
Clamping force = projected area of product in the direction of opening and closing mould (cm2) ×the number of mold cavity×in-mold pressure (kg/cm2);
Projected area of product in the direction of opening and closing mould is generated by the product appearance size.
In-mold pressure is different with different materials, generally take 350-400 kg/cm2.
The machine clamping force is usually greater than 1.17 times of the bulging force.

Enough injection quantity: the weight of product and the number of mold cavity determine the “injection quantity” and select the appropriate “screw diameter”.
For stability purpose, the injection volume required for more than 1.35 times of the product, which means the product weight should less than 75% of the injection amount.

Plastic injection or plastic material molding is actually a process accustomed to help make a multitude of industrial items in addition to components. The actual making associated with plastic material injection begins with thermoplastic pellets. These are the pellets which are usually made from the polymer glued plastic resin.

The actual pellets need to be placed on the injection device. Usually, this is achieved by starting them all in to a hopper which RSS feeds the particular melted thermoplastic pellets into a barrel that is warmed. The actual juncture where the hopper fulfills the actual warmed up barrel and it is often cooled down to prevent the actual pellets inside the hopper by burning prematurely. The particular barrel is warmed up mainly from the changing of the auger located inside of it. More often, the competitors heating units are used to provide extra warmness to the barrel.

The pellets comes down in feed hopper from near the back of the actual gun barrel. The particular auger within the barrel which resembles an extremely big mess is turned by the motor. The particular auger may alter at one rate, however upon the few machines, the auger price may modify or programmed to improve and lower from times. Since the auger is really rotated through the engine, the actual polycarbonate pellets at rear of the barrel are usually drawn forward slowly. The actual elevated servings related to auger, categorized as flights and its purpose is to accomplish this sketching forward procedure.

Since the pellets tend to be attracted, forward heat in the shear of the auger rotation and also the earthenware heating units concerning the barrel can start to melt the actual pellets right into a liquid kind. The actual dissolved plastic material amasses at the front of the barrel, behind the nozzle attached to the middle.

Once an adequate amount of the actual dissolved plastic has accumulated at the rear of the particular misting nozzle, the equipment is ready to supply the plastic material to the mildew. There are two primary kinds of mould being used for that plastic material injection procedure. The initial kind of secure is known as Direct-Hydraulic Locking mechanism. This particular uses hydraulic pressure to maintain the particular mold close plus place throughout the injection procedure. Another kind is famous the actual Toggle Locking mechanism. With the Toggle Securing system, the mildew can also be used shut making use of gas pressure. However the mold is actually secured along with a real latch.

Plastic injection molding is often thought to be a hard process which is a wrong notion of the people. A variety of parts are manufactured using Injection molding process which varies from the smallest component to an entire body component of a car.

The machinery involved in plastic injection molding is costlier and very sensitive and complex equipment. These machines are called as injection molding machines. The machines used are also heavy and some even weigh upto tons of kilogram. But only when these kind of machines are used the final product turns out to be a quality product. This is so because the plastics are fed into these machines and they are heated until they become fluid. This shows that the machines should withstand high temperature and hence the need for a complex equipment.

Plastic materials used for the injection moulding process are thermoplastics or thermosetting plastics. Both the thermoplastic and thermosetting plastics are polymers. Some widely used thermoplastics are nylon, polyethylene, and polystyrene while bakelite, vulcanized rubber are the widely used thermosetting plastic. Sometimes a polymer with a very high elasticity is also used. Such a polymer is called elastomer.

The plastic takes the shape of the cavity or the mold used and get solidified or settled in it. After being solidified it is ejected out After some time molded material is ejected out from the cavity. The same cavity can be used to make any number of molds. The mold is of any desired shape.

The injection molding machine has two components namely the injection unit, the mold and the clamping unit. One should not forget that the process involved in plastic injection molding is not as tough as the size of the machinery. It is a very simple and a systematic process. Initially the injection molding process starts with the injection of the plastic resins or polymers into the injection barrel. The resins are heated to melting point and now the fluid is poured into the mold which is of the desired shape needed. The mold has two components namely the injection mold and the ejector mold. The melted plastic resin in poured into the mold using a sprue the injection mold. And the ejector mold helps in ejecting the plastic part after it is solidified in the mold without any damage using ejecting pins.

The next step is the application of hudraulic or mechanical pressure. This is done in order to allow the trapped air in the mold to escape. This is called the dwelling process. After the pressure is applied the air cavities move to one corner of the mold. Then the fluid is allowed to solidify and the mold is cooled. Finally the solidified plastic part is ejected from the mold either manually or automatically.

After the cooling process there is often change in the mechanical that is both physical and chemical properties of the plastic part. The thickness of the mold is one of the important design considerations of the injection molding process. Usually a mold with an uniform wall thickness is preferred. Thus plastic Injection mold reduces the change in mechanical properties of the plastic part.