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√ 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.

ADDlTlVE - A substance added to a plastic compound to alter its characteristics. Examples are plasticizers, and flame retardants. ALLOY - A combination of 2 or more plastics which form a new plastic.  AMORPHOUS - A plastic material in which the molecular structure is random and becomes mobile over a wide temperature range. ANNEAL ~ To heat a moulded part up to a temperature just below its melting point and slowly cooling it back; down to room temperature. This relieves moulded stresses. ANlSOTROPlC SHRlNKAGE - S hrinkage that occurs more in one direction (usually the direction of flow; reinforced materials shrink more across the direction of flow) than another. AUTOMATIC OPERATlON -The term used to define the mode in which a moulding machine is operating when there is no need for an operator to start each cycle. BARREL - A metallic cylinder in which the injection screw (or plunger) resides in the moulding machine . Also called CYLINDER. BLEND -...

1. Intense industry competition often results in low profit margins. 2. Mould costs are high. 3. Moulding machinery and auxiliary equipment costs are high. 4. Lack of knowledge about the fundamentals of the process causes problems. 5. Lack of knowledge about the long term properties of the materials may result in long-term failures.

1. The Screw type Injection Moulding Machine consists of a hopper, a reciprocating screw and barrel assembly, and an injection nozzle. 2. This system confines and transports the plastic as it progresses through the feeding, compressing, degassing, melting, injection and packing stages. 3. A single screw injection Moulding machine for themoplastic showing the plasticizing screw,al a barrel band heaters to heat the barrel, a stationary platen, and a movable platen.

1. The plunger type injection moulding machine is available horizontal or vertical type and operated pneumatically or hydraulically.The clamping and Injection may be Semi or automatic. 2. In a semi Automatic type the clamping cylinder & the Injection cylinders are operated by levers which is connected the pneumatic or hydraulic cylinders. In Automatic type, the cylinders are actuated automatically to a set timers.

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...

• A  toggle  is  mechanically  device  to  amplify  force. • In  a  moulding  machine,  which  consists  of  two  bars joined,  together  end  to  end  with  a  pivot  . • The  end  of one  bar  is  attached  to  a  stationary  platen, and  the  other  end  of  a  second  bar  is  attached  to  the movable  platen. • When the  mould  is open,  the  toggle  is  in  the  shape  of  a  V. • When pressure  is  applied  to  the  pivot,  the  two  bars  form a  straight  line.

PE is made up from Ethylene monomers. PE is divided into different class according to their density. Different types of PE are as below: ( Polymers )                   ( Density ) LDPE               0.910 -0.940 (g/cc) LLDPE             0.915 -0.925 (g/cc) MDPE              0.926 -0.940 (g/cc) HDPE               0.941 -0.959 (g/cc) VLDPE             0.880 -0.915 (g/cc) UHMWPE        0.930 -0.935 (g/cc) Properties of PE: √ Very low cost √  Excellent chemical resistance √  Very good processability. √  High impact s...

1. Hand Injection Moulding Machine  (Vertical) . (Click Here) 2. Plunger Type Injection Moulding Machine (vertical & Horizontal). (Click Here) 3. Screw Type Injection Moulding Machine. (Click Here) 4. Plunger - Plunger Injection Moulding Machine. 5. Screw - Plunger Injection Moulding Machine.

√ The function of the torpedo is to help the material for proper melting and crate back pressure for help in mixing. Torpedo used Vartical Hand Injection Machine .

1. A devices made of two dissimilar metals which are used to measure the temperature of a heated area such as the barrel or nozzle. 2. It sends a signal to controller which then turns off or  on to control the temperature of that area.

1. Parts can be produced at high production rates.  2.Large volume production is possible. 3.Relatively low labour cost per unit is obtainable.  4. Part require little or no finishing.  5. Many different surface, colours, and finishes are available.  6. Good decorations is possible.  7. For many shapes this process is the most economical way to fabricate.  8. Process permits the manufacture of very small parts which are almost impossible to fabricate in quantities by other methods. 9. Close dimensional tolerances can be maintained.  10. Parts can be moulded with metallic and non-metallic inserts.

√ 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...

√ General Rules for Safety&Precaution  ,Fitter tools,  Introduction of polymers & Fundamental Termininology of polymers PDF files- (Download)

Solid Cross - 1. A Typical Die Design for extruding a solid rod is show in figure. 2. In the figure, DD is the diameter of die orifice,  DB is the diameter of bore of extruder barrel, α is the lead -in angle ,  and  P is the die land. 3. Because of the screen pack and breaker plate assembly,   the pressure in the extruder (PE)  is reduced by the pressure loss across the assembly (PL). 4. Since the die outlet is at atmospheric pressure,  the working pressure is the die pressure (PD)   given by the difference : PD = PE -- PL

Straight - Through Dies : √ Those die whose axes are arranged to be in line with the direction of supply of melt. √ Spider,  mandrel is needed for tubes . √ Used for the extrusion of pipe ,  rod ,  profiles and sheet . Crosshead  Dies - • Arranged with their axes at an angle of 908 (458 and 308 are also used)  to the melt feed.  •No need to for Spider assembly . Used for the production of insulated wires,  cables.  Offset Dies - • Combination of both straight - through die and off-set dies.  • Used for the production of pipe. 

Die Design - 1. The role of a die is to from the melt into a desired linear product : fibres, films, sheets, profiles, rods , etc . 2. The die is a channel, whose profile changes from that of the extruder bore to an orifice, which produces the required form. 3. The dies can be classified using different criteria.     Example - Considering cross section of the extrudate one may recognize dies to produce -     • Solid Cross - Sections (Click Here)     • Hollow Cross - Sections 4. Another classification scheme is based on the die attachment to the  extruder barrel -     • Straight - throught Dies - (Click Here)      • Cross - heat dies-  (Click Here)     • Offset dies - (Click Here)

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...

Screw Cooling - 1. Larger screws are bored though for passage of heat transfer medium. However, care must be used not to over-cool the screw. 2. The cooling may be freeze a layer of plastic on the screw root, reducing the channel depth thus producing more shear at a cost throughput. 3. This may  also reverse the required relationships between the friction coefficient (low friction coefficient on the screw, high on the barrel),  further reducing the drag flow. 4. Furthermore,  there is a danger that the material staying a long time near the screw root will degrade,  contaminating the product. 5. It is important to remember that the conveying ability of the screw is controlled by the friction coefficient ratio : f(barrel)/ f(screw) it is important to maximize this ratio. 6. Under normal circumstances the minimum value of the ratio that guarantees conveying is 1.4 7. Screw cooling may be recommended to prevent decomposition of heat sensitive materials. 8. H...