Manufacture of Plastics Products - II Moulding Processes for Plastics in which All the three dimensions of article get defined Dr. R. S. Basargekar Reliance Industries Ltd
Major Moulding Processes Types of processes Thermoplastics moulding processes Thermosetting Moulding Process Injection Moulding Compression moulding Blow Moulding Transfer Moulding Rotational Moulding FRP shaping processes Lay-Up Moulding Resin Transfer moulding Filament winding
Major Moulding Processes Major Moulding Processes Thermosetting processes Thermosetting processes Thermoplastic processes Thermoplastic processes � Material � Material in in solid solid or or � Plastics material in solid � Plastics material in solid semisolid semisolid form form fed fed to to form is melted form is melted mould mould � The molten material is � The molten material is � Mould is heated and many � Mould is heated and many times pressure applied to times pressure applied to shaped with the help of shaped with the help of effect a chemical change effect a chemical change mould mould � In FRP processes the � In FRP processes the � The material is cooled by � The material is cooled by material may be liquid to material may be liquid to begin begin with, with, undergoes undergoes cooling the mould and cooling the mould and chemical chemical change change to to article taken out article taken out solidify solidify
Injection Moulding Injection Moulding � The process defines all the three dimensions of the � The process defines all the three dimensions of the article quite accurately. article quite accurately. � Advances in machinery, moulds and materials � Advances in machinery, moulds and materials continuously going on to produce articles with desired continuously going on to produce articles with desired dimensions and properties. dimensions and properties. � Highly automated mass production is possible, highly � Highly automated mass production is possible, highly complex shapes can be produced in single operation, complex shapes can be produced in single operation, assembly of sub-components can be avoided. assembly of sub-components can be avoided. � Selection of machine and material, setting of machine � Selection of machine and material, setting of machine parameters and proper product and mould design are parameters and proper product and mould design are important factors to achieve reproducible planned important factors to achieve reproducible planned quality. quality.
Injection Moulding Applications Injection Moulding Applications � House hold Articles like � House hold Articles like bucket, mugs, boxes bucket, mugs, boxes etc. etc.
Injection Moulding Applications Injection Moulding Applications � Appliances like TV, � Appliances like TV, transistor, computer transistor, computer cabinets, washing cabinets, washing machine parts, etc. machine parts, etc.
Injection Moulding Applications Injection Moulding Applications � Automotive components � Automotive components like bumper, instrument like bumper, instrument panel, interior trims, panel, interior trims, handles etc. handles etc.
Injection Moulding Applications Injection Moulding Applications � Furniture - moulded � Furniture - moulded chairs, tables, stools chairs, tables, stools etc. etc. � Luggage - shells of � Luggage - shells of bags bags
Injection Moulding process Injection Moulding process � Compound containing additives like filler, colourant � Compound containing additives like filler, colourant etc. or material granules blended with masterbatch etc. or material granules blended with masterbatch granules added to hopper of machine. granules added to hopper of machine. � Material melted between revolving screw of certain � Material melted between revolving screw of certain geometry and cylinder heated externally. geometry and cylinder heated externally. � Molten material pumped into mould which defines � Molten material pumped into mould which defines shape and size. shape and size. � Material cooled and ejected from mould. � Material cooled and ejected from mould. � Cyclic process with cycle times now reduced to less � Cyclic process with cycle times now reduced to less than one minute. than one minute.
Injection Moulding process - Injection Moulding process - Schematic Schematic
Injection moulding Machines Injection moulding Machines � Machine choice depends on the article to be � Machine choice depends on the article to be moulded, the size of mould, rate of production etc. moulded, the size of mould, rate of production etc. � Main specifications include clamping force in tonnes, � Main specifications include clamping force in tonnes, plasticizing capacity, shot capacity etc. plasticizing capacity, shot capacity etc. � The machine can be manual or automatic. � The machine can be manual or automatic. � The controls include temperature of barrel and � The controls include temperature of barrel and nozzle, the shot weight, the injection speed (time), nozzle, the shot weight, the injection speed (time), injection pressure, hold-up pressure, cooling time etc. injection pressure, hold-up pressure, cooling time etc. � The mould temperatures also can be controlled by � The mould temperatures also can be controlled by cooling/ heating. cooling/ heating.
Moulds for injection moulding Moulds for injection moulding � Two halves of mould are clamped on machine � Two halves of mould are clamped on machine platens. platens. � The mould consist of major parts/systems such as : � The mould consist of major parts/systems such as : − Cavity and core to define article geometry − Cavity and core to define article geometry − Material delivery system consisting of sprue, runners − Material delivery system consisting of sprue, runners and gate and gate − Article ejection mechanism − Article ejection mechanism − Additional cores - movable and non movable to define − Additional cores - movable and non movable to define the holes and openings in articles etc. the holes and openings in articles etc. − Ejection system push-back mechanism − Ejection system push-back mechanism − Sprue locking mechanism (cold slug well) to facilitate − Sprue locking mechanism (cold slug well) to facilitate sprue and runner material removal sprue and runner material removal
Injection Mould Injection Mould
Sandwich Moulding Process Sandwich Moulding Process
Blow moulding Blow moulding � A process in which polymer in molten or rubbery � A process in which polymer in molten or rubbery stage is inflated against the cool surfaces of mould. stage is inflated against the cool surfaces of mould. � The articles obtained are hollow containers and can � The articles obtained are hollow containers and can have necks with threads to facilitate closing by caps have necks with threads to facilitate closing by caps and lids. and lids. � Intricate shapes such as fuel tanks in modern � Intricate shapes such as fuel tanks in modern automobiles, washing ware bottles can be attained. automobiles, washing ware bottles can be attained. � The mould consists of two halves, in the opening of � The mould consists of two halves, in the opening of the container- usually the neck- a blowing pin is used the container- usually the neck- a blowing pin is used to blow air. to blow air. � The article thickness is not uniform but can be � The article thickness is not uniform but can be brought close to uniformity by programmable brought close to uniformity by programmable parisons etc. parisons etc.
Applications of blow moulding Applications of blow moulding � Bottles � Bottles � Containers � Containers � air ducts in auto-AC � air ducts in auto-AC systems systems � Intricate shape closed � Intricate shape closed containers like auto-fuel containers like auto-fuel tanks tanks � clear medicinal bottles � clear medicinal bottles � Baby feeding bottles � Baby feeding bottles
Major types of Blow Moulding Major types of Blow Moulding � Major types of blow moulding are: � Major types of blow moulding are: − Extrusion Blow moulding − Extrusion Blow moulding − Injection Blow moulding − Injection Blow moulding − Injection stretch moulding − Injection stretch moulding − Extrusion stretch blow moulding − Extrusion stretch blow moulding
Extrusion Blow Moulding Extrusion Blow Moulding � Molten cylinder - known as parison is extruded out of � Molten cylinder - known as parison is extruded out of the die of extruder - continuously or intermittently the die of extruder - continuously or intermittently � The parison is clamped in two halves of the mould � The parison is clamped in two halves of the mould � The neck of the container gets defined by blowing pin, � The neck of the container gets defined by blowing pin, which blows air. which blows air. � The Polymer gets blown to conform to the geometry � The Polymer gets blown to conform to the geometry defined by the mould halves. defined by the mould halves. � By having multi-station process using more moulds � By having multi-station process using more moulds rate of production can be high rate of production can be high � The parison thickness can be varied by parison � The parison thickness can be varied by parison programming through die and thereby thickness can be programming through die and thereby thickness can be more uniform. more uniform.
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