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What is the difference between an injection molding machine and an extruder?

Update:25-03-2021
Summary:

1. The working principle is different 1. Injection mold […]

1. The working principle is different

1. Injection molding machine
The working principle of the injection molding machine is similar to the syringe used for injection. It uses the thrust of the screw (or plunger) to inject the plasticized plastic in the molten state (that is, the viscous fluid state) into the closed mold cavity. The process of obtaining the product after curing and shaping.

Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding-melting and plasticizing-pressure injection-mold filling and cooling-mold opening and picking. After taking out the plastic part, the mold is closed again for the next cycle.

2. Extruder

A single screw is generally divided into three sections in the effective length. The effective length of the three sections is determined according to the diameter, pitch and depth of the screw, which are generally divided by one-third of each.

The last thread of the material port is called the conveying section: the material must not be plasticized here, but it must be preheated and compacted. In the past, the old extrusion theory believed that the material here is loose, and later proved that the material here is actually The solid plug means that the material here is a solid like a plug after being squeezed, so as long as it completes the conveying task, it is its function.

Two, the characteristics are different

1. Injection molding machine

The injection device and the clamping device are on the same vertical centerline, and the mold is opened and closed in the up and down direction. Its floor space is only about half of that of a horizontal machine, so it is about twice as productive when converted into floor space.

PET Preform Injection Molding Machine

2. Extruder

The safety items that the extruder should pay attention to when extruding are: electricity, heat, mechanical rotation, and the loading and unloading of bulky parts. The extruder workshop must be equipped with lifting equipment, assembling and disassembling the head, screw and other heavy parts to ensure safe production.

Three, the classification is different

1. Injection molding machine

Classified by plasticization method

1) Plunger plastic injection molding machine

It has poor mixing properties and poor plasticization properties, so a shunt shuttle device must be installed. Has been rarely used.

2) Reciprocating screw type plastic injection molding machine;

Relying on the screw for plasticization and injection, the mixing and plasticizing properties are very good, and the most used.

3) Screw-the plunger plastic injection molding machine relies on the screw for plasticization and the plunger for injection, the two processes are separated.

2. Extruder

Plastic extruders are divided into twin screw extruders and single screw extruders.

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