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Issue #16 · created by jaynedarby


Research The Unique Technology Of Injection Molding Machine

Injection molding is also called injection molding, a type of injection as well as molding technique. The benefits of the injection molding method are fast production speed, high performance, automated procedure, selection of colors, straightforward to intricate forms, huge to tiny dimensions, exact product sizes, very easy to update products, as well as the ability to develop complex-shaped forms components. Injection molding is suitable for automation, complex-shaped products, and also various other molding processing fields.

At a particular temperature level, the liquified plastic product is stirred by a screw, infused right into the mold and mildew cavity with high stress, and afterwards cooled and healed to get molded items. This technique is suitable for the mass production of complex-shaped components and also is just one of the important handling methods.

Injection molding procedure

Temperature control

Injection molding equipment and molds

Barrel temperature.

The injection molding process requires temperature level control of barrel temperature level, nozzle temperature, and also mold temperature level. The initial two temperature levels mainly influence the plasticization and flow of the plastic, while the last temperature mainly impacts the flow as well as air conditioning of the plastic. Each plastic has a various flow temperature. The exact same plastic has different circulation as well as disintegration temperatures due to various resources or qualities due to typical molecular weight and also molecular weight distribution.

Nozzle temperature level.

The nozzle temperature level is generally slightly lower than the maximum barrel temperature to avoid feasible "drool" of the thaw in the straight-through nozzle. Nozzle temperature level need to not be as well reduced. Otherwise, it will certainly cause early condensation of the thaw and also clog the nozzle or very early condensation of the material right into the mold dental caries and also impact the item's efficiency.

Mold and mildew temperature level.

Mold temperature has a considerable effect on the intrinsic efficiency as well as obvious high quality of the item. The crystallinity of the plastic establishes the temperature of the mold, the size and framework of the item, the efficiency needs, as well as other process conditions (melt temperature, injection speed, stress, molding cycle, and so on).

Stress control

The pressure in the injection molding process consists of plasticizing pressure and also injection pressure and also directly affects the plasticization of plastics and also item top quality.

Plasticizing pressure.

( Backpressure) When making use of a screw-type injection machine, the stress on the top of the screw when the screw turns back the melt is called plasticizing pressure, likewise known as backpressure. The magnitude of this stress can be readjusted by the relief valve in the hydraulic system.

In injection, the magnitude of the plasticizing pressure varies with the design of the screw, the quality needs of item, and also sort of plastic. If these problems and the speed of the screw are stated to be constant, boosting the plasticizing stress will certainly enhance the shearing effect, i.e

. It will raise the temperature of the thaw, however it will certainly reduce the performance of plasticization, increase heartburn and also leakage, and increase the driving power.

Furthermore, raising the plasticizing stress usually results in a consistent temperature of the melt, consistent mixing of the colorants, as well as the discharge of gases from the melt. General

Stress Account in Injection Molding

In operation, the choice of the plasticizing pressure needs to be as low as possible to ensure the outstanding quality of the item. The details value varies with the selection of plastic made use of however seldom goes beyond 20 kg/cm2.

Injection pressure.

In existing manufacturing, the injection stress of mostly all injection machines is based on the top of bettor or screw against plastic.

In the existing production, the injection stress of all injection machines is based upon the stress related to the plastic by the top of bettor or screw (converted from the oil line stress). The duty of injection pressure in injection molding is to conquer the resistance to the circulation of plastic from the barrel to the tooth cavity, provide the melt a rate of loading the mold, as well as small the melt.

Injection Molding

Molding Cycle

The time required to complete an injection molding process is called the molding cycle, likewise called the molding cycle. It consists of the adhering to parts.

Injection Molding Cycle

Molding cycle: The molding cycle straight impacts labor performance and devices utilization. As a result, in the production process, the proper time in molding cycle must be reduced as long as possible under the facility of quality control. In the whole molding cycle, injection time and also cooling time are one of the most essential, and they have a decisive influence on the top quality of items.

The mold and mildew filling up time in the injection time is directly vice versa symmetrical to the mold filling price, and the mold and mildew loading time in production is generally regarding 3-5 secs. The holding time in the injection time is the pressure time of the plastic in the cavity, which represents a huge percentage of the entire injection time, generally about 20-120 seconds (as much as 5-10 mins for additional thick parts).

Prior to the thaw is iced up at the gate, the amount of holding time affects the dimensional precision of the item, yet if it is later on, it has no result. The holding time additionally has a minimum worth, which is known to rely on the product temperature level, the mold temperature, and the dimension of the main channel and also gateway. If the size of the major channel as well as entrance as well as the process problems are basic, the pressure worth that yields the minor fluctuation in the contraction of the product generally prevails.

The cooling time is mainly determined by the thickness of the item, the thermal and crystalline homes of the plastic, and the mold temperature level. The end of the cooling time should guarantee that the items do not cause modifications when getting rid of the mold. As a concept, cooling time is generally about 30 to 120 secs in between the cooling time.

Air conditioning time is as well lengthy unnecessary, not only to reduce manufacturing performance, yet complex components likewise cause troubles in the release of the mold. The forced launch will also generate launch anxiety. Various other time in the molding cycle is connected to whether the production process is constant and automated and also the degree of continuity and automation.

Criteria

Injection pressure

The injection pressure is given by the hydraulic system of the injection molding system. The pressure from the hydraulic cylinder is moved to the plastic thaw through the injection molding machine screw. Press plastic melt by the pressure and enter the upright runner (for some mold and mildews, it is additionally the leading jogger), the primary jogger, the manifold, and also the mold dental caries through the gate of the injection molding machine. Stress exists to overcome the resistance in the melt circulation procedure. On the other hand, the resistance in the flow process needs to be countered by the stress of the injection molding machine to make sure that the filling up process proceeds efficiently.

The stress is greatest throughout the injection molding procedure at the injection molding machine nozzle to get rid of the resistance to flow throughout the thaw. Subsequently, the pressure gradually reduces along the circulation size toward the front end of the thaw at the wavefront. If the inner exhaust of the mold tooth cavity is great, the final pressure at the front end of the thaw is the atmospheric pressure.

Numerous elements influence the thaw loading pressure, which is summarized in 3 classifications.

Material aspects, such as kind of plastic, viscosity, and so on.

Architectural factors include the putting system's type, number, as well as area, the mold tooth cavity shape, and the item's density.

Refine aspects of molding.

Injection time

The injection time pointed out right here is the moment needed for the plastic melt to fill up the cavity, leaving out the additional time such as mold and mildew opening as well as closing. Although the injection time is brief and also has little effect on the molding cycle, the change of injection time considerably influences the stress control of gates, joggers, as well as dental caries. A proper injection time aids to fill the thaw preferably as well as is very essential to improve the surface top quality of the item and also minimize the dimensional tolerance.

The injection time is much lower than the cooling time, regarding 1/10 to 1/15 of the cooling time, and also this rule can be used as a basis for predicting the complete molding time of the part. In the mold circulation analysis, the injection time is equal to the injection time embeded in the process conditions just if the screw rotation fills the melt. If the screw stress switch happens before the tooth cavity is filled up, the analysis outcome will be higher than the process conditions.

Injection Temperature

The injection temperature level is a crucial factor influencing the injection pressure. The injection molding machine barrel has 5 to 6 home heating areas. Each raw material has its appropriate processing temperature level (exact handling temperature can be discovered in the data given by the product supplier). The injection molding temperature level need to be regulated within a certain array.

If the temperature level is too reduced, the thaw will be improperly plasticized, impacting the high quality of the shaped parts as well as making the process more difficult; if the temperature level is expensive, the raw product will be conveniently broken down. The injection temperature level is commonly higher than the barrel temperature level in the actual injection molding procedure. The higher value is connected to the injection rate and the product's performance, as much as 30 ℃. The temperature level is because of the high warmth produced by the shearing of the melt via the injection port. There are two ways to make up for this difference in mold flow analysis. One is to gauge the temperature of the thaw during empty injection, and also the various other is to include the injection nozzle in the modeling.

Holding stress as well as time

Near completion of the injection procedure, the screw stops rotating as well as advancements, whereupon the injection gets in the holding stress stage. The nozzle of the injection molding machine is constantly loading the tooth cavity to fill the volume vacated by the shrinkage of the component. If the tooth cavity is filled up without holding pressure, the component will reduce concerning 25%, especially at the ligaments, because of too much contraction and also the formation of shrinkage marks. The holding pressure is typically regarding 85% of the optimum filling stress, however certainly, it should be figured out according to the real scenario.

Back pressure

The back stress is the stress that requires to be gotten over when the screw reverses and recedes to save the material. Using high back pressure is conducive to the diffusion of color and plastic melting however at the exact same time prolongs the screw retraction time. Lowering the size of plastic fibers and also enhancing the pressure of the injection molding machine, so the back pressure ought to be reduced, generally not greater than 20% of the injection stress.

When injecting foam, the back pressure should be greater than the stress formed by the gas. Or else, the screw will be pushed out of the barrel. Some injection molding machines can set the back pressure to make up for the reduction in screw size during melting, which will minimize the warm input and also reduce the temperature. Nonetheless, because such adjustments are challenging to approximate, it is challenging to readjust the machine appropriately.

If you would like to know more about Min-Hui injection molding machines, you can call us.


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