Definition-injection molding is one of the mostly used technique of manufacturing plastic articles from plastic raw materials.In this technique raw material is heated up to certain specific temperature so that it is able to flow state and then it is injected into the mould under pressure to get the desired product.
Types of injection molding machines
- hand operated molding machines
- Plunger type injection molding machine
- Reciprocating screw type injection molding machines
- Plunger plunger molding machines
5.Screw plunger molding machines..
Hand operated molding machines –such type of machine are operated manually by operator. They are available at low cost.in these machines mould is aligned in vices so that nozzle is in straight to sprue of mould and when pressure is applied nozzle come in contact with sprue. Hence material is injected into mold, cooled and then ejected manually. In the process when handle is pressed circular movement of rack and pinion changes into straight movement of plunger which then push the plastic in the barrel injected into mould..
Here production efficiency is low so there is need of automatic mode of process.
2. Plunger type of injection molding machines –
In these machines there is material feeding hopper ,a barrel with hydraulic oriented plunger inside it ,mold nozzle, and hydraulic cylinder
When material is heated up to flow state the piston is applied hydraulically to inject the material into mold.
3. Screw type molding machines-
here a plunger is replaced by screw and whole parts are same.
4-screw plunger type machines-
In these machines material is fed into hopper then material is heated into barrel after reaching to flow state the material is transfer to screw maintained at same temperature then this screw moves forward to inject the material into the mould.
5. Plunger plunger type injection molding machines
This machine is same as former one but there is one more plunger that replaces screw to inject the material into the mould..
Mode of injection molding process-
1-hand operated machines
2 semi operated machines3
3- automatic operated molding machines.