Plastic Mold, Plastic Injection Mold & Injection Molding Power Shell

Plastic Mold, Plastic Injection Mold & Injection Molding Power Shell

Service Details:

  • Brand:Kayou
  • Serial Number: M-0019
  • Country of Origin:Shenzhen, China
  • Certificate:ISO9001

Payment & Shipping Terms:

  • Price Quote:Negotiable
  • Minimum Order: 1
  • Average Delivery Time:25days
  • Payment Method:T/T
  • Package Details:Wooden Case
  • Ability to Supply:5 Set/per month
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Plastic Mold, Plastic Injection Mold & Injection Molding Power Shell

Description

Plastic Mold

Selection and control of injection molding process conditions
Pressure
Including: injection pressure, pressure and back pressure.
Injection pressure, which is complementary to the injection speed, plays a decisive role in the flow and filling of the plastic melt; the pressure is closely related to the holding time, which mainly affects the cavity pressure and the final molding quality; the back pressure is related to the screw speed. The size affects the plasticizing process, plasticizing effect, and plasticizing ability of the material.

Injection pressure and injection speed

Injection pressure

What is injection pressure?

Refers to the pressure exerted by the head on the plastic melt when the screw (or plunger) moves axially.

Injection pressure effect:

In the injection molding process, it is mainly used to overcome the flow resistance of the melt in the entire injection molding system, and to a certain degree of compaction of the melt.


Injection pressure loss includes: dynamic pressure loss and static pressure loss.

Dynamic pressure loss, consumed in the flow resistance of the nozzle, runner, gate and cavity to the melt, and viscous friction inside the plastic melt itself, is proportional to the melt temperature and volume flow, and is subject to the flow path of each section. The length, cross-sectional dimensions and rheological properties of the melt.

Static pressure loss, consumed in injection and packing flow, is related to melt temperature, mold temperature and nozzle pressure.

The injection pressure selection is too low. Due to excessive pressure loss during the injection molding process, the cavity pressure is insufficient, and the melt will be difficult to fill the cavity: the injection pressure is selected too much, although the pressure loss can be relatively reduced, but There may be undesirable phenomena such as rising molds and flashing materials, causing large pressure fluctuations, difficult to control the production operation, and easy to overload the machine.

Effect of Injection Pressure on Melt Flow, Filling and Parts Quality

When the injection pressure is not too high and the gate size is large, the melt is filled.

The flow is relatively stable. At this time, because the mold temperature is lower than the melt temperature, the melt is cooled, and the melt is easily deposited at the cavity near the gate, and the length of the stream is shortened, which makes the cavity difficult. full.

When the injection pressure is large and the gate is small, the melt will generate jet flow in the cavity. The flow first impacts the surface of the cavity and then spreads. It is easy to form bubbles and silver in the workpiece. Will burn the parts due to excessive friction heat. Therefore, the injection pressure should be selected moderately, and if possible, the injection pressure should be chosen to be larger, which will help to increase the filling speed and the length of the flow, and also increase the weld line strength and shrinkage rate of the part. . Note that after the injection pressure is increased, the stress in the part may also increase, which will affect the stability of the shape and size of the part after demolding.
The advantage of higher injection speed: faster melt flow rate, higher temperature, higher shear rate, lower melt viscosity, lower flow resistance, longer flow length and cavity pressure When the product is enlarged, the parts will be denser and more uniform, and the strength of the weld line will be improved. The dimensional error of the part produced by the multi-cavity mold is also small.

Disadvantages of excessive injection speed: as with excessive injection pressure, causing jet flow in the cavity, resulting in poor quality of the part. In addition, if the exhaust gas is poor at high-speed injection, the air in the cavity will be severely compressed, which not only slows down the flow rate of the high-speed flowing melt, but also burns the workpiece due to the exothermic heat of the compressed gas or thermally degrades.

The actual practice of determining the injection speed in production:

The slow low pressure injection is used first, and then the injection speed is adjusted according to the injected parts to achieve a reasonable value. If the production batch is large, it is necessary to shorten the molding cycle. During the adjustment process, the injection speed can be adjusted as much as possible in the direction of higher value, but it must be ensured that the quality of the part cannot be deteriorated because the injection speed is too fast.

Should try to use high-speed injection:

Plastics with high melt viscosity, high heat sensitivity, plastics with fast forming cooling speed, large thin-walled, precision parts, long-flow parts, fiber reinforced plastics. Do not use too fast injection speed.

 

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Plastic Mold, Plastic Injection Mold & Injection Molding Power Shell

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Work Time :
8:30-18:00(Beijing time)
FAX :
86-7552-3156569
Business Phone :
86-7552-3156569(Working time)
Factory Address :
E bulding 220th Reixing industrial Park XingYe Road Wusha ChangAn GuangDong provice China

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