The process of injection

Tempreture  control

Barrel temperature: injection molding process to control the temperature of the barrel temperature, nozzle temperature and mold temperature. The first two kinds of temperature mainly affect the plasticization and flow of plastics, and the latter one mainly affects the flow and cooling of plastics. Each plastic has a different flow temperature, and the flow temperature and decomposition temperature of the same plastic vary depending on the source or brand, due to the difference in average molecular weight and molecular weight distribution. The plasticizing process of plastics in different injection machines is different, so the temperature of the selected cartridge is different.

Nozzle temperature: nozzle temperature is usually slightly lower than the top temperature of the barrel to prevent the “salivation” that may occur in the straight-through nozzle. The nozzle temperature should not be too low, otherwise, the nozzle will be blocked by the early solidification of the melt, or the properties of the product will be affected by the injection of the early solidification into the die cavity.

Mold temperature: mold temperature has a great impact on the internal properties and apparent quality of products. Mold temperature depends on the crystallinity of plastics, size and structure of products, performance requirements, and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.)

Pressure control

Injection pressure includes plasticizing pressure and injection pressure, and directly affects plastic plasticization and product quality.

When a screw injector is used, the pressure on the top of the screw is called plasticizing pressure, also known as the back pressure, when the screw rotates and recovers. This pressure can be adjusted by the relief valve in the hydraulic system. In injection, the size of the plasticizing pressure needs to change with the design of the screw, the quality requirements of the product and the type of plastic. If these conditions and the rotating speed of the screw do not change, increasing the plasticizing pressure will strengthen the shearing effect. The melt temperature will be increased, but the plasticizing efficiency will be reduced, the countercurrent and leakage will be increased, and the driving power will be increased.

In addition, increasing the plasticizing pressure can make the melt temperature uniform, the color mixture uniform and the gas discharged from the melt. In general operation, the determination of plasticizing pressure should be as low as possible on the premise that the quality of the product is good. The specific value varies according to the type of plastics used, but usually rarely exceeds 20 kg / square centimeter.

Injection pressure: in current production, the injection pressure of almost all injection machines is plastic at the top of the plunger or screw

The applied pressure (converted from the oil line pressure) shall prevail. The role of injection pressure in injection molding is to overcome the flow resistance of plastic flowing from the cylinder to the cavity, to give the filling rate of the melt material and to compaction the melt material.

molding cycle

 

Forming cycle: forming cycle directly affects labor productivity and equipment utilization. Therefore, in the production process, the quality should be guaranteed, as far as possible to shorten the molding cycle of the relevant time. Injection time and cooling time are the most important factors in the whole molding cycle, which have a decisive effect on the quality of the product. The filling time in injection time is inversely proportional to the filling rate, and the filling time in production is generally about 3-5 seconds. The pressure holding time of injection time is the pressure time of plastic in mold cavity, which accounts for a large proportion in the whole injection time, which is usually about 20-120 seconds (up to 5 ~ 10 minutes for extra thick parts). Before the melting material is frozen at the gate, the pressure holding time has an effect on the accuracy of the product size, and if it is later, it will have no effect on the size accuracy of the product. The pressure-holding time also has the most favorable value, which is known to depend on the feed temperature, mold temperature, and the size of the main channel and gate. If the dimensions and process conditions of the main channel and gate are normal, the pressure value of the minimum range of shrinkage of the product is usually obtained. The cooling time mainly depends on the thickness of the product, the thermal properties and crystallization properties of plastics, and mold temperature. The end point of cooling time should be based on the principle that no change will be caused when the product is demoulded. The cooling time is generally between 30 and 120 seconds, and the cooling time is unnecessary. It not only reduces the production efficiency, but also causes difficulties in demoulding for complex parts. Demoulding stress will even be produced when the mold is forced to be demoulded. Other times in the forming cycle are related to whether or not the production process is continuous and automated, and the degree of continuity and automation.

 

About JasonMould Industrial Company Limited


Jasonmould is a manufacturer of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer- plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Contact:
Contact person: James Yuan
Company name: JasonMould Industrial Company Limited
Address: LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Telephone: 86-752-6682869
Email: info@jasonmolding.com
Website: https://www.jasonmolding.com

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