MCQ’s On Moulding with Polymers
Q. What is the minimum pressure required in a compression molding process?
A. 0.5 MPa
B. 1 MPa
C. Q.5 MPa
D. 2 MPa
.
Answer: A
Explanation: Processing of thermosetting plastics is classified as, compression molding and transfer molding. The minimum pressure that is required for the complete operation of compression molding is 0.5 MPa.
Q. What is the minimum temperature required in a compression molding process?
A. 120°C
B. 125°C
C. 130°C
D. 135°C
.
Answer: B
Explanation: None.
Q. What is the maximum pressure required in a compression molding process?
A. 35 MPa
B. 40 MPa
C. 45 MPa
D. 50 MPa
.
Answer: D
Explanation: The maximum pressure that is required for the complete operation of compression molding is 50 MPa.
Q. What is the maximum temperature required in a compression molding process?
A. 240°C
B. 245°C
C. 250°C
D. 255°C
.
Answer: C
Explanation: Processing of thermosetting plastics is classified as, compression molding and transfer molding. The maximum temperature that is required for the complete operation of compression molding is 250°C.
Q. In compression molding, the curing time does not depend on which of the following factors?
A. Material
B. Curing temperature
C. Geometry
D. Thickness
.
Answer: B
Explanation: When there has to be molding done for thermosetting materials, mainly compression molding is preferred. While doing this, curing has to be done. The time needed for curing depends on the material used, geometry and thickness of the material.
Q. What is the maximum curing time required in a compression molding process?
A. 2 minutes
B. 3 minutes
C. 4 minutes
D. 5 minutes
.
Answer: D
Explanation: The maximum curing time that is required for the complete operation of compression molding is 5 minutes.
Q. What is the minimum curing time required in a compression molding process?
A. 0.4 minutes
B. 0.5 minutes
C. 0.6 minutes
D. 0.7 minutes
.
Answer: B
Explanation: The minimum curing time that is required for the complete operation of compression molding is 0.5 minutes.
Q. What is the maximum pressure required in a transfer molding process?
A. 80 MPa
B. 90 MPa
C. 100 MPa
D. 120 MPa
.
Answer: C
Explanation: Processing of thermosetting plastics is classified as, compression molding and transfer molding. The maximum pressure that is required for the complete operation of transfer molding is 100 MPa.
Q. What is the minimum pressure required in a transfer molding process?
A. 20 MPa
B. 40 MPa
C. 50 MPa
D. 70 MPa
.
Answer: A
Explanation: The maximum pressure that is required for the complete operation of transfer molding is 20 MPa.
Q. Speed of production in transfer molding is higher than that of compression molding?
A. True
B. False
.
Answer: A
Q. Thermosetting materials are the polymeric materials which get soften on heating with or without pressure.
A. True
B. False
.
Answer: B
Explanation: Thermosetting materials are the polymeric materials that get permanent hardness once the heat is given to the material. These are the polymers which require heat and pressure to mould them into shape. These polymers cannot be re-softened once they are set and hardened by heat.
Q. Thermosetting plastics are generally used for making products of high strength and rigidness.
A. True
B. False
.
Answer: A
Explanation: Thermosetting polymers basically involve cross-linked molecular structure and thus it is ideal for making products which demand rigidity and strength. Due to cross linking in thermosetting polymers, these are made hard, tough, and cannot be re-moulded as thermoplastic polymers.
Q. Which of the following types of molecular structure present in thermosetting polymers?
A. Linear polymers
B. Branched polymers
C. Cross-linked polymers
D. Network polymers
.
Answer: C
Explanation: Cross-linked polymers are described by adjacent linear chains that are brought one to another at several locations by covalent bonds. Cross linking is completed by a non-reversible chemical reaction. Often, cross-linking is finished by additive atoms which are covalently bonded to the chains in the thermosetting polymers.
Q. Polyurethanes plastics can be made in flexible foams even after belonging to thermosetting polymers.
A. True
B. False
.
Answer: A
Explanation: Polyurethane plastics are belonged to the thermosetting plastics or polymers. Polyurethane is the only polymer that can be formed in both rigid and flexible foams. The flexible polyurethane foam is generally used in the manufacturing of mattresses, carpets and furniture. And the rigid polyurethane foam is used in making of chairs and mirror frames.
Q. Polyethylene, polypropylene and polyvinyl chloride (PVC. are the main example of thermosetting polymers.
A. True
B. False
.
Answer: B
Explanation: Polyethylene, polypropylene and polyvinyl chloride (PVC. are basically examples of thermoplastics material. And thermosetting material’s example includes polyurethanes, polyesters, epoxy resins and phenol resins which are used for manufacturing of aircraft parts, tires and auto parts.
Q. Thermosetting plastics like epoxies can be used for filament wound rocket motor casings in missiles by combining with glass fibers.
A. True
B. False
.
Answer: A
Explanation: Epoxies can be used in various ways. In adding with glass fibers, it is capable of making composites that are of high strength and heat resistant. These composites are basically used for making motor casings in missiles, aircraft parts, fixtures etc. Epoxies are also found in industrial equipment and in protective coatings of appliances.
Q. Polyurethane plastics are highly reactive to chemical compounds due to lack of elasticity in these plastics.
A. True
B. False
.
Answer: B
Explanation: Polyurethane plastics come in the category of thermosetting plastics. In this type of plastics, elasticity is generally very high. Due to this property of high elasticity, it can be used in decorative and protective coatings. The high elasticity also makes these polyurethane polymers highly resistant to any chemical attack.
Q. Phenolic plastics can also be used as binder for holding plies of wood in making of plywood.
A. True
B. False
.
Answer: A
Explanation: Phenolic plastics or polymers are belongs to thermosetting plastics. These are the special type of resins which can be used in potting compounds, casting resins, and laminating resins. They can also be used in making of electrical equipment. Phenolic plastics are very popular binders for holding plies of wood in manufacturing of plywood.
Q. Thermosetting plastics can be used for manufacturing of windshield for airplane.
A. True
B. False
.
Answer: B
Explanation: For the manufacturing of windshield for airplane, poly-acrylics plastics are used which basically belongs to the group of thermoplastics. Poly-acrylics are transparent, high tough in nature and can be easily shaped in any form. Due to such properties of this material, it is widely used for making of windshields for airplane.
Q. Mechanical properties of any plastics are mainly dependent on the temperature, force and time of load applied.
A. True
B. False
.
Answer: A
Explanation: Mechanical properties relate to movement or breakage of the polymer due to some mechanical variation such as application of load. Mechanical properties are mainly dependent on the temperature, force or load applied, and the duration of time the force is applied. It can also be affected by ultra-violet radiation when used outside.
Q. How is the die used in injection molding cooled?
A. Oil
B. Air
C. Water
D. Contact with cold surface
.
Answer: C
Explanation: When it comes to molding of polymers in thermoplastics, injection molding process is the most common of the methods. In this method, whenever the die has to be cooled, there is water used to cool it.
Q. How does the piston in the clamping unit move?
A. Hydraulic energy
B. Pneumatic energy
C. Heat energy
D. Suction
.
Answer: A
Explanation: There is a clamping unit employed for holding the two halves together and for the opening and closing of the mold. A moving piston is provided which operates the power press. This piston works on hydraulic energy.
Q. Where does the granular molding material get loaded into?
A. Barrel
B. Hopper
C. Pellets
D. Split
.
Answer: B
Explanation: In a ram or plunger type injection molding system, the granular molding material has to be first loaded into a hopper, after which, with the help of a feeding device it gets metered out inside a cylinder.
Q. Which of the following material is not made by injection molding?
A. Nuts
B. Tubes
C. Car handles
D. Electrical fittings
.
Answer: B
Explanation: Injection molding is one of the most widely used method of molding among molding with polymers. There are various applications of this method such as nuts, bolts, cups, car handles, electrical fitting parts, but not tubes and rods.
Q. What is the minimum temperature allowed to be given to the injection molding process?
A. 120°C
B. 130°C
C. 140°C
D. 150°C
.
Answer: D
Explanation: In the molding process of polymers in thermoplastics, injection molding process is the most common of the methods. The minimum allowable temperature that can be given to the system is 150°C.
Q. Which of the following factors is not considered in a ram type injection molding?
A. Inner pressure of material
B. Outer pressure of material
C. Volume of material
D. Temperature of material
.
Answer: C
Explanation: Among the following, the inner pressure of the material, the outer pressure of the material as well as the mold and the temperature of the material and mold are important factors to be considered. The volume of material is not counted among important factors.
Q. What is the minimum pressure allowed to be given to the injection molding process?
A. 90 MPa
B. 100 MPa
C. 140 MPa
D. 170 MPa
.
Answer: B
Explanation: None.
Q. What is the maximum temperature allowed to be given to the injection molding process?
A. 300°C
B. 320°C
C. 350°C
D. 400°C
.
Answer: A
Explanation: The maximum allowable temperature that can be given to the system is 300°C, in this particular method of molding.
Q. The barrel is used for the opening and closing of the mold.
A. True
B. False
.
Answer: B
Explanation: A barrel is an instrument that is placed near the nozzle, and it plays no role in the opening and closing of the mold. There is a clamping unit employed for holding the two halves together and for the opening and closing of the mold.
Q. There is a varied pressure provided in the solidification unit of injection molding process.
A. True
B. False
.
Answer: B
Explanation: Injection molding is considered to be one of the most widely used methods. In this method, there are dies that eject the solidified component, before which it is kept under constant pressure.
Q. Which of the following processes of moulding is widely used for the manufacturing of bottle caps and automotive dashboards?A. Compression moulding
B. Transfer moulding
C. Injection moulding
D. Jet moulding
.
Answer: C
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.
Q. Complex shape of parts or components cannot be formed by the injection moulding process.
A. True
B. False
.
Answer: B
Explanation: 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.
Q. Components from injection moulding process are made very expensive due to the application of very costly equipment.
A. True
B. False
.
Answer: B
Explanation: 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.
Q. The three mould technique is generally preferred than the two mould technique in injection moulding process.
A. True
B. False
.
Answer: A
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.
Q. Which of the following cooling systems is used in injection moulding process to increase solidification rate of components made?
A. Air jet cooling system
B. Water cooling system
C. Cooling with free convection
D. Cooling with fins
.
Answer: B
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.
Q. The moulding directions in injection moulding can affect the cost of equipments used in the process.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. The flow of plastic in the mould cavity is more proper and smooth if the thickness of the component made is very small.
A. True
B. False
.
Answer: B
Explanation: 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.
Q. Shrinkage of the plastic parts in mould cavity can results in generation of sink holes in the plastic.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. A heavy surface finishing is always required for components made in injection moulding machine.
A. True
B. False
.
Answer: B
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.
Q. In injection moulding process, ribs are generally provided for the reinforcement to avoid sink marks from the component.
A. True
B. False
.
Answer: A
Explanation: In order to have reinforcement, ribs can be used which mainly avoid the problem of marks formed on the parts. Reinforcing ribs are generally provided perpendicular to the parting line and made thinner than the mould walls. It is always recommended that the thickness of the ribs should lie between 40% and 60% of wall thickness.
Q. In blow molding, to inflate soft plastic, which medium is used?
A. Air
B. Water
C. Oil
D. Alcohol
.
Answer: A
Explanation: 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.
Q. Which of the following plastics is not used in blow molding?
A. Terephthalate
B. Polypropylene
C. Polythene
D. PVC
.
Answer: A
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.
Q. What is the minimum air pressure required in the blow molding process?
A. 350 kPa
B. 400 kPa
C. 450 kPa
D. 500 kPa
.
Answer: B
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.
Q. What can be the maximum pressure to be given to plastic for blow molding process?
A. 700 kPa
B. 750 kPa
C. 800 kPa
D. 850 kPa
.
Answer: C
Explanation: Air with an extreme amount of pressure, when is needed, it might mean the material is thicker and denser. The amount of pressure that can be provided depends totally on the material. The maximum pressure that can be provided in blow molding process is 800 kPa.
Q. Which of the following is not a type of blow molding process?
A. Injection blow molding
B. Extrusion blow molding
C. Multi-smaller blow molding
D. Multi-larger blow molding
.
Answer: C
Explanation: Blow molding basically is a process of inflation of air under pressure into the plastics inside the mold cavity. There are only three known types of blow molding, namely, injection blow molding, extrusion blow molding and multi larger blow molding.
Q. What is the minimum thickness required by the plastic for vacuum forming?
A. 0.125 mm
B. 0.25 mm
C. 0.375 mm
D. 0.5 mm
.
Answer: A
Explanation: 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.
Q. Which of the following is not an application of blow molding process?
A. Toy bodies
B. Door liners
C. Bottles
D. Pipes
.
Answer: B
Explanation: 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.
Q. What is the maximum thickness that can be allowed for a plastics sheet in a vacuum forming process?
A. 3 mm
B. Q.1 mm
C. Q.2 mm
D. Q.3 mm
.
Answer: C
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 Q.2mm.
Q. The heater in the vacuum forming process is heated up to 90°C.
A. True
B. False
.
Answer: A
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.
Q. The initial cost in blow molding is low.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. Which of the following moulding processes is widely used for the manufacturing of plastic bottles?
A. Compression moulding
B. Injection moulding
C. Jet moulding
D. Blow moulding
.
Answer: D
Explanation: 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.
Q. Blow moulding is a very slow process, however economical for producing products with better quality.
A. True
B. False
.
Answer: B
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.
Q. In extrusion blow moulding process, it is very difficult to trim away excess of plastics.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. Single stage stretch blow moulding is always preferred than two stage stretch blow moulding for increase in production rate.
A. True
B. False
.
Answer: B
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.
Q. Single stage stretch blow moulding process is mostly used for small level production.
A. True
B. False
.
Answer: A
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.
Q. Thermoforming process involves injecting of molten plastic into a mould cavity by application of compressed air.
A. True
B. False
.
Answer: B
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.
Q. In thermoforming process, it is very difficult to control thickness of moulded parts or sheets.
A. True
B. False
.
Answer: A
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.
Q. In thermoforming, it is very easy to mould the plastic materials which are of crystalline nature.
A. True
B. False
.
Answer: B
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.
Q. Thermoforming is basically a cheap process as compared to injection and blow moulding process.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. Which of the following materials is mostly used for making of thermoforming moulds?
A. Steel
B. Grey cast iron
C. Aluminium
D. White cast iron
.
Answer: C
Explanation: 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.
Q. Which of the following material is not used in extrusion?
A. Wax
B. Granules
C. Powder
D. Pellets
.
Answer: A
Explanation: 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.
Q. In extrusion process, extra shearing occurs in which part of the system?
A. Feed section
B. Pumping section
C. Collapse section
D. Transition section
.
Answer: B
Explanation: The section where an additional amount of melting and shearing occurs is called a pumping section.
Q. Melting section is another name for which section?
A. Feed section
B. Transition section
C. Pumping section
D. Collapse section
.
Answer: B
Explanation: 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.
Q. How are extruded materials cooled?
A. Water
B. Contact with chilled surface
C. Air
D. Oil
.
Answer: D
Explanation: 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.
Q. Which of the following is not an important factor of cooling in extrusion?
A. Reduction in shrinkage
B. Reduction in distortion
C. Ease of adding colours
D. Rate of cooling
.
Answer: C
Explanation: 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.
Q. Which of the following is not an application of polymer extrusion?
A. Door insulation seals
B. Chewing gums
C. Cables
D. Circuit boards
.
Answer: D
Explanation: Circuit boards is not an application of polymer extrusion. Door insulation seals, chewing gums and cables are the applications of polymer extrusion.
Q. Film extrusion process, best involves film having a thickness below what length?
A. 0.2 mm
B. 0.3 mm
C. 0.4 mm
D. 0.5 mm
.
Answer: D
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.
Q. In the cable extrusion process, what is the speed of product winding?
A. 40 m/sec
B. 50 m/sec
C. 60 m/sec
D. 70 m/sec
.
Answer: B
Explanation: 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.
Q. Calendering is mostly suited for making PVC.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. Tubes having U shape cannot be manufactured by polymer extrusion process.
A. True
B. False
.
Answer: B
Explanation: Polymer extrusion has a variety of applications such as candy canes, chewing gums, window frames, solid rods, pipes or tubes having U or J sections.
Q. Extrusion is a process that uses an electric system for processing various polymers.
A. True
B. False
.
Answer: B
Explanation: Extrusion is a process used for the processing of various types of thermoplastics and rubbers. The extrusion process is a simple process in which liquid or molten polymer is forced through a shaped die by applying high pressure. The pressure is basically generated by the action of screw rotation against the barrel wall in the extrusion process.
Q. Which of the following equipment is used for controlling the temperature of polymer material in the extrusion process?
A. Thermo resister
B. Thermometer
C. Thermocouple
D. Glass tube
.
Answer: C
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.
Q. Thermosetting polymers can be processed by extrusion process by forming cross-linking in the extruder.
A. True
B. False
.
Answer: A
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.
Q. In processing polymers, injection moulding process is almost similar to extrusion process except for the screw operation.
A. True
B. False
.
Answer: A
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.
Q. Extruder is a device used for the finishing of processed polymer products in the extrusion process.
A. True
B. False
.
Answer: B
Explanation: 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.
Q. Continuous type of extruder is generally equipped with rotating parts in the extrusion process.
A. True
B. False
.
Answer: A
Explanation: 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.
Q. Multiple screw extruders are mostly preferred than the single screw extruders in the extrusion process.
A. True
B. False
.
Answer: B
Explanation: In the extrusion process, extruders are equipped with a screw as their main mixing part. Screw extruders are mainly of two types which are single and multiple screw extruders. In most of the cases, single screw extruders are used for the processing of polymer materials in the industries, because of its simple design, low cost and high reliability.
Q. In the extrusion process, a cast type barrel is mainly used for the heating of polymer material.
A. True
B. False
.
Answer: B
Explanation: 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.
Q. Extruder die is a machine part that gives final shape to the polymer material used in the extrusion process.
A. True
B. False
.
Answer: A
Explanation: Extruder die is a machine part that gives final shape to the polymer material in the extrusion process. It produces a channel through which liquid polymer exit the extruder by applying pressure that increases in the barrel during the process. The liquid polymer comes out from the die with a constant speed, that’s why the design of die is very important for specification and accuracy.
Q. In the extrusion process, a water cooling system is used which automatically controlled by a sensor.
A. True
B. False
.
Answer: A
Explanation: 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.
