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A brief introduction to injection molds

update:13-07-2019
abstract:

Plastic molding can have a variety of techniques, but i […]

Plastic molding can have a variety of techniques, but injection molding resins are the most common materials. The large machine is called an injection molding machine that completes the injection molding, the plastic part is forced to melt, the mold cools, then hardens, shapes the shape, and produces a reverse image mold.

Injection molding is a low-cost technique for creating plastic parts that are both simple and complex. The operation of the injection molding machine is that the granular plastic enters the heating barrel from the hopper by gravity, a spiral plunger slowly moves the particles forward, the plastic is forced into the heating chamber to melt, the plunger advances, and the molten plastic is forced into the mold through the nozzle, allowing It enters the mold cavity, the mold cools, and the plastic solidifies in the mold.

The injection molding commodity economy is a good form, but the injection molding efficiency is different, the quantity is different, the small quantity is the most ideal, the simple machine can be completed, the injection molding is a tens of billions of dollars of industry, and 32% of the plastic is processed by injection molding. The formation, the cheap and sustainable injection molding has become the choice of many consumer goods and industrial projects, which has a profound impact on modern society.

Injection mold parts are widely used in aerospace, automotive, engineering prototypes, hydraulics, pneumatics, packaging, construction, electrical, fiber optics, medicine and dentistry, power tools, agriculture, electronics, physics, measuring instruments, communications, caps, accessories, valves , toys, levers, cameras, etc.

Four stages of injection molding

The first stage

Granular or powdered thermoplastics enter the injection molding machine from the hopper.

second stage

The injection molding machine includes a hollow steel cylinder containing a rotating screw (Archemidial screw) with plastic along the barrel to the injection mold.

The heater surrounds the barrel to melt the plastic as it travels along the barrel.

The third phase

Collected as molten plastic at the end of the barrel.

Once there is enough plastic to collect, a hydraulic plunger pushes the screw forward to inject into the mold cavity through the gate plastic.

The mold is warmed and plastic injected quickly before injection to prevent the mold from becoming full before it hardens.

Fourth stage

The pressure is maintained for a short period of time (residence time) to prevent material shrinkage and dents on the back side during set-up (hardening) and finally to cool.