Plunger-Plunger injection Moulding Machine

√ As the plastic industry developed a second type plunger machine appeared. known as two stage plunger.

√ This type of equipment involved two plunger units set on top of other the one to plasticize the material and feed it to another cylinder that consist of a chamber to heat the plastic material by conduction and plunger that operates as a shooting plunger and push the plasticize material into the mould.

Advantages

• Faster than conventional machine (single plunger) .
• No Pressure loss encountered in compacting the granules.

• Allows larger parts with more projected area.

Disadvantage :

• Extra construction for pre plasticizing so cost is more.

Breaker Plate & Screen Pack :

Breaker Plate - 1. This is performed metal disk, with a multitude of small diameter holes. 2. The breaker plate is placed in between the screw and the die assembly. 3. It's principal function is to provide support for the screen pack . 4. The breaker plate helps also to convert the spiral flow of the polymer melts leaving the screw into a linear, axial one. Screen Pack - 1. Screen Pack is usually a multilayered, nearly symmetrical sandwich of metallic wire screens. 2. It is placed between the screw and the breaker plate, using the latter for physical support. It's role is to eliminate the particulate contaminants. 3. The screen pack composition is always based on trade-offs, there is need to eliminate particulates using screens with high mesh, but at the same time this create flow restriction, it reduced the throughput, thus low mesh would be preferred. 4. Decision should be made as for as the maximum tolerabl...

Advantage and Disadvantages of Injection Blow Moulding Process

√ Advantages - { injection Blow Moulding } 1. Accurate shaping of the neck. 2. A High level of dimensional accuracy. 3. Mini weight tolerance. 4. The highest quality surface finish. 5. Production absolutely free from waste. 6. Crystal clear containers for pharmaceutical application. 7. Finished bottle without weld line and scrap. 8. Secondary /finishing operation can be avoided. 9. Multi-cavities can be operated. √ Disadvantages -{ injection Blow Moulding } 1. The preform design generally establish the core rod length & diameter. 2. The process is more expensive than extrusion blow moulding. 3. Compromise between preform wall thickness and blow up ratio. 4. The ratio of the maximum wall thickness to minimum wall thickness across a preform cross-section should be less than 1.5 to prevent weld lines. 5. Preform thickness greater than 6 mm is unstable during blowing since the thick section cannot be properly conditioned. 6. The technique is not suit...

Vertical Hand injection Machine

1. The cost of the machines is increased depending on their functions and Size . 2. The simplest Injection Moulding machine is a hand injection moulding machine With a very low cost . 3. The simplest mode of injection moulding machine may be considered as hand operated mode, which is an apt equipment to underStand the interaction of major operating parameters . 4. The machine consists of Barrel, Plunger, Band Heaters along with energy regulator, Rack & Pinion system for injecting the material by the plunger, a torpedo and nozzle. 5. The clamping is done manually on a working table. The machine is fitted on the working table. Heating is set manually . 6. The capacity of . the machine is available from 0.5 Oz to 2 Oz. Once heating is achieved the production starts manually. 7. The quality of the product is completely depend upon the skill of the operaton .The heating set point is achieved by heat & trial method. 8. Although Temperat...

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