The Injection Moulding Process is a manufacturing process used for producing parts or components by injecting molten material into the mold cavity. Injection molding can be performed with only one of these materials like glass, plastics, etc. and most commonly, thermoplastic polymers are used.
Note: It is applicable to thermoplastic materials only.
The Injection Moulding Machine was invented by John Wesley Hyatt, patented in 1872.
In the last articles, we had discussed Blow Moulding process whereas in Todays article, we will discuss on the Injection Moulding Process along with its diagram, Parts, Working principle, Advantages, Disadvantages & Applications.
The parts of the Injection Moulding Machine are as follows.
Explanations of the parts of the Injection Moulding Machine are as follows.
1. Reciprocating Screw:
The reciprocating screw rotates by means of a motor and the reciprocating motion is provided by a hydraulic system.
The thermoplastic granules are to be used in the Injection moulding Machine to create solid components.
By the use of a hopper, the plastic granules are to be poured into the molding machine.
It acts as a source of heat for heating the plastic granules to the molten state.
A nozzle of the required size is to be placed at the end of the heating zone so that, molten material enters from it and acquires the required shape.
6 and 8. Fixed Pattern and Moving Pattern:
These are the two patterns that are placed side by side so as to form a mold. Among the two patterns, one is the fixed pattern and the other is the movable pattern.
During Solidification, the molten metal present in between these patterns can stay for some time and after that, the moving pattern moves aside, and thereby final product is obtained.
7. Mould Cavity:
It is the place where solidification takes place between the fixed pattern and moving pattern and the formation of the component takes place.
9. Final Product:
Thus the final product will be obtained after cooling.
The defects of Injection Molding are as follows.
When some of the molten plastic escapes from the mold cavity then the defect arises called Flash.
When the molten plastic does not completely fill the mold cavity due to any of the reasons, then there will be a shortage of molding called a Short shot.
Vacuum voids are caused due to the uneven solidification between the inner section and surface of the prototype.
In Injection molded products, when the shrinkage occurs in the inner portions then small depressions develop in thicker regions called Sink marks.
Burn marks are rust-colored and can appear on the surface of Injection molded components.
Weld lines can appear on the components when the molten plastics meet each other as they are flowing from two different parts of the mold.
Delamination is nothing but peeled off. It is a condition where thin surface layers appear on the component due to contaminant material. These thin surface layers appear like coatings and can be delaminated i.e. peeled off.
In different parts of the mold component, when the shrinkage is uneven then it is called warping.
Due to the difference in speed of the injection of molten metal, the molten plastic sticks to the mold surface only, and this is a failure of not completely solidifying in the mold cavity.
This is the explanation for the defects of the Injection Molding Process.
The advantages of Injection Moulding Process are as follows.
The disadvantages of Injection Molding Process are as follows.
The applications of the Injection Moulding Process are as follows.
Watch a Youtube video on the Injection Moulding Process.
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