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The correct CHOICE is (a) True

To explain: In the extrusion process, the extruder includes a water cooling system that circulates around the barrel mechanism. The water cooling system is generally CONTROLLED by a SENSOR that automatically controls the system. The sensor also selects the temperature at a PREDEFINED point in the processing section of polymer MATERIALS.

Correct option is (b) False

For explanation I would say: There are MAINLY two types of barrel HEATERS used in the extrusion process, which are band and cast barrel. The band type barrel is used for heating the polymer MATERIAL while the cast type includes some channels to contain a flow of cooling medium which is USUALLY water, but the oil is more preferred because it can prevent thermal shock to the barrel.

Right option is (a) True

To elaborate: There are mainly two types of extruder in the extrusion process of POLYMERS, which are continuous and discontinuous extruder. Continuous extruders are generally fitted with rotating components. And in discontinuous extruders, plastic or polymer is EXTRUDED in a recurrent manner, which is only SUITABLE for batch type production processes like INJECTION moulding.

Right option is (b) False

The best I can explain: In the extrusion process, extruder is a MACHINE tool or device that forces DUCTILE and soft heated solids through die openings of the desired shape to produce a continuous film, STRIP, or TUBES of polymer materials. In this process, many kinds of polymers like thermoplastics, thermosetting, ELASTOMERS etc. are processed with the help of extruder.

Right answer is (a) True

Explanation: Extrusion process is mostly used for thermoplastics POLYMER materials; it can also be used for PROCESSING the elastomers and THERMOSETTING polymers, which basically causes cross-linking in the extruder during the heating process of polymer material. The plastic or polymer PRODUCTS can be further formed by the thermoforming process.

Correct ANSWER is (c) Thermocouple

The best explanation: In extrusion process, polymer material pellets are fed into an EXTRUDER by a hopper. Then the material is conveyed by a feeding screw and forced through a shaped die that converts polymer materials into continuous polymer products. Heating elements are placed on the BARREL which soften and melt the polymer. The TEMPERATURE of the polymer material is mainly CONTROLLED by thermocouples.

Correct answer is (a) True

Explanation: Injection moulding PROCESS is similar to extrusion process. The only difference between the two processes is in the screw operation. In extrusion, screw ROTATES continuously which provides OUTPUT of continuous products like pipe, rod and sheet. A reciprocating screw is used in injection moulding which rotates while moving in FORWARD and BACKWARD directions.

The correct choice is (a) True

The best I can EXPLAIN: Calendering process is considered to be ONE of the most important SHEET forming process. Calendering has many products like phenyl, cellulose or vinyl floor tiles. It is most suited for making PVCs.

The correct OPTION is (d) 0.5 mm

BEST explanation: EXTRUSION of films is one of the most important PROCESSES in extrusion. For the films having a thickness below 0.5 mm, these films are best suited for extrusion and can be further applied for making various bags.

The correct OPTION is (b) 50 m/sec

To elaborate: For the insulation purpose, the coating of any wire or CABLE is one of the most vital polymer extrusion PROCESS. The wire is cooled and then it is wound to large spools at a speed of 50 meters per SECOND.

The correct ANSWER is (d) Circuit boards

To explain I would say: Circuit boards is not an application of POLYMER extrusion. Door insulation seals, chewing gums and cables are the APPLICATIONS of polymer extrusion.

The correct option is (C) Ease of adding colours

To elaborate: There are various FACTORS of cooling, a few of them are, REDUCTION in SHRINKAGE, reduction in DISTORTION and the rate of cooling too has to be considered.

Right ANSWER is (d) Oil

To explain I would say: On completion of EXTRUSION, the material is very hot and has to be cooled down. There are various agents which are used cooling these MATERIALS down, such as, air or WATER or its direct contact with a very cold SURFACE.

The CORRECT option is (b) Transition section

The explanation is: Melting section is one of the types of EXTRUSION in polymers. Extrusion is a process of forcing PLASTIC which is at a very high temperature, through the dies, and gets opened at a required SHAPE. Melting section is ANOTHER name for transition section.

Right ANSWER is (B) PUMPING section

Explanation: The section where an additional amount of melting and SHEARING occurs is called a pumping section.

The correct answer is (a) Wax

To explain: Extrusion is a process of forcing PLASTIC which is at a very high temperature, through the dies, and gets OPENED at a required shape. The raw materials used for extrusion with polymers contain granules, POWDER and thermoplastic pellets.

Correct answer is (c) Aluminium

To explain: Thermoforming moulds are always made of aluminum because of its light WEIGHT, machine ability, and good thermal conductivity. Aluminum moulds may also contain passages through which WATER can be PUMPED for cooling of components, which may greatly AFFECT the shrinkage and other FEATURES of the components made.

Right choice is (a) True

For explanation I would say: Thermoforming can be used in both high and LOW volume production processes. The main advantage of this process includes low initial tooling and equipment COSTS. DUE to this, this process is cheaper when compared with INJECTION and blow moulding processes. Thermoforming is widely used for production of PARTS for industries including medicals, appliances etc.

Correct OPTION is (b) False

Explanation: The most widely used plastic materials in thermoforming process are amorphous or non-crystalline nature. This mainly includes moulding of plastic materials such as polyvinyl chloride (PVC), polyethylene, polystyrene, acrylic, polycarbonate ETC. Crystalline nature of materials cannot be moulded through this process.

The correct option is (a) True

The best explanation: In thermoforming process, the tooling is MAINLY CHEAP to produce, but the process LEAVES small marks on the moulded sheets that can be controlled. But the main quality control issue possesses non-uniform thickness of parts or sheets which are difficult to handle, this may also result in WARPING or TEARING of the moulded sheet.

Correct choice is (B) False

The best explanation: In thermoforming process, a sheet of plastic is used which covers the shape of any DIE by HEATING it to the desired temperature and then it is stretched over the die using vacuum, thus it is also CALLED as vacuum forming. Then the pressure is applied to the plastic sheet by using pressurized air.

The correct answer is (a) True

For explanation: Single stage process includes an extruder to inject LIQUID plastic into the MOULD where the plastic is cooled to form a preform (tube of plastic). This preform is reheated and placed in the bottle mould. Then it is stretched by using COMPRESSED air in the mould cavity. This all processes require too much time to accomplish themselves, so it is only SUITABLE for small level PRODUCTION.

Right OPTION is (a) True

For explanation I would SAY: Extrusion blow moulding process is a type of blow moulding in which air is injected into the neck of container to blow up the plastic material that then occupies the mould cavity. In this method, TOOLING COST is low but it INCLUDES some difficulties in trimming away of excess plastic, it also possess high scrap rate of the plastic material.

The CORRECT answer is (b) False

The explanation: Two stage stretch blow moulding is same as SINGLE stage stretch blow moulding, except preforms (TUBE of plastic) which are already made in the two stage process. The single stage process is generally accomplished by using single MACHINE, where the two stage process USES preforms that already present in the process. This results in saving of time which directly increases production rate.

Right answer is (b) False

The best EXPLANATION: The blow moulding process is very FAST and can produce components mainly plastic parts very fast and economically. The process can be completed by MANUAL MEANS or by semi-automatic or automatic machines. Blow moulding process is especially used for the production of plastic BOTTLES.

Right choice is (d) Blow moulding

To ELABORATE: In blow moulding process, a heated tube of plastic material is situated between the TWO halves of mould, then the mould is closed and air or inert gas is usually blown at a PRESSURE of 200 – 400 bars, which HELPS in expanding of tube outward to occupy the mould cavity. After that the part cools down to get hardened and then the part is ejected from the mould.

Correct option is (a) True

To explain I would say: In BLOW MOLDING, there is a mold cavity present INSIDE the soft plastic, into which, the air with high amount of pressure has to be BLOWN. The capital REQUIRED for mold initially is quite less, making it a little inexpensive process.

The correct option is (a) True

The best explanation: In VACUUM forming process, there is a clamp that has to be used for holding the PLASTIC sheets. There is a HEATER employed for heating the MOLD cavity. The heater brings the polymer in a temperature RANGE of 55°C to 90°C.

Right choice is (c) 3.2 mm

The best explanation: Vacuum forming process is ONE of the important PROCESSES that are employed in thermoforming processes. The maximum thickness of the PLASTIC sheet has to be NOTED, as a clamp is to be fitted around the plastic sheet. The maximum allowable thickness of this plastic sheet is 3.2mm.

Correct option is (B) DOOR liners

The explanation is: Among the FOLLOWING, only door liners is not an application of blow molding PROCESS. Internal door liners are made using THERMOFORMING process, while toy bodies, bottles and pipes are made using blow molding process.

The correct option is (a) 0.125 mm

The best I can EXPLAIN: Vacuum FORMING is ONE of the classifications of thermoforming PROCESSES. Around its circumference, a clamp is attached or we NEED to know the minimum thickness. The minimum thickness that can be allowed for this operation is 0.125 mm.

The correct answer is (a) Terephthalate

Explanation: For BLOWING processes, there are CERTAIN plastics only which are properly suited for the OPERATION, while any other material might fail. Hence, for OPERATING through blow molding process, POLYPROPYLENE, polythene and PVC are used.

The correct OPTION is (b) 400 kPa

Explanation: In the blow molding PROCESS, there is some amount of pressure that has to be given to the AIR for blowing the bottles. The amount of pressure to be given depends on the material. The minimum pressure that can be given in this process is 400 kPa.

Right answer is (a) Air

For explanation I would SAY: BLOW molding process is typically used for the blowing process of hollow plastics. While blow molding, the plastic has to be inflated, in order to do so, air has to be blown INSIDE with a high AMOUNT of PRESSURE.

Right option is (b) False

The explanation: Injection MOULDING is very advantageous when it needs to manufacture intricate parts in abundant quantity. In injection moulding machine, components are often MOULDED directly in the machine with SURFACE finish and other features like color thereby excluding the secondary finish, which ALSO EXCLUDES the cost of further machining.

The correct option is (a) True

The explanation is: Shrinking of plastic in mould cavity can result sink holes which are a TYPE of DEFECT that can ruin the PRODUCT. To avoid such DEFECTS, cross-sectional thickness should be maintained uniformly throughout the component. And ribs and gussets must be used which provides mechanical strength to the parts MADE in the mould.

Correct option is (a) True

The explanation is: The MOULDING DIRECTIONS involved in injection moulding process basically DETERMINES number of CAMS or inserts which to be USED in the process. And if the number of inserts used is more, then the cost involvement will also be more. The moulding is always made in such a way to optimize number of cams as well as the cost.

Right option is (b) False

The explanation is: In injection moulding PROCESS, if the component THICKNESS is very small, then the PLASTIC flow is prevented due to high friction. The flow can also be restricted if the gate is very far away from the features of the geometry, or a OBSTRUCTION in path of flow may also result in PREVENTION of flow.

Right choice is (a) True

Explanation: The design in three mould technique has some advantages that it allows more even distribution of melt into the sides of mould cavity. And ALSO provides more AUTOMATION to the moulding process in comparison with two mould technique. So, the three mould technique is ALWAYS preferred than the two mould technique in INJECTION moulding process.

The correct choice is (b) Water COOLING system

Explanation: The cooling system is made by including some passages in the mould walls that are usually CONNECTED to an EXTERNAL pump. Cool water is circulated through the passages to extract heat from the hot polymers or plastics components made in the injection MOULDING process. This cooling system INCREASES the solidification rate which basically reduces the production time.

The correct answer is (b) False

For explanation I would say: In INJECTION molding process, dies are costly to produce parts; the dies can be used to form THOUSANDS of parts at very faster rate, so that COST of components reduces that implies this method is very economical for large scale production which can produce any simple or complex products in ABUNDANT AMOUNT.

The correct answer is (b) False

To elaborate: Injection moulding is a most common and dominant of all the other plastic processing methods. The process of injection moulding is very versatile and can produce very complex SHAPED components with the APPLICATION of multisided moulds. In this process, EVEN components with METAL inserts can also be produced.

Correct answer is (c) Injection moulding

The explanation: Injection moulding is a manufacturing process which uses thermoplastic and THERMOSETTING plastic materials to make products like bottle CAPS, automotive DASHBOARD, combs etc. In this process, material is fed into a barrel of high temperature, then by mixing it is forced into a mould cavity where it solidifies and gets HARDENED.