Manufacture of Plastics Products - II Moulding Processes for - - PowerPoint PPT Presentation

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

Rotational Moulding Blow Moulding Injection Moulding Thermoplastics moulding processes Lay-Up Moulding Resin Transfer moulding Filament winding FRP shaping processes Transfer Moulding Compression moulding Thermosetting Moulding Process Types of processes

Major Moulding Processes Major Moulding Processes

Thermoplastic processes

Plastics material in solid

form is melted

The molten material is

shaped with the help of mould

The material is cooled by

cooling the mould and article taken out Thermoplastic processes

Plastics material in solid

form is melted

The molten material is

shaped with the help of mould

The material is cooled by

cooling the mould and article taken out Thermosetting processes

Material

in solid

• r

semisolid form fed to mould

Mould is heated and many

times pressure applied to effect a chemical change

In FRP processes the

material may be liquid to begin with, undergoes chemical change to solidify Thermosetting processes

Material

in solid

• r

semisolid form fed to mould

Mould is heated and many

times pressure applied to effect a chemical change

In FRP processes the

material may be liquid to begin with, undergoes chemical change to solidify

Injection Moulding Injection Moulding

The process defines all the three dimensions of the

article quite accurately.

Advances in machinery, moulds and materials

continuously going on to produce articles with desired dimensions and properties.

Highly automated mass production is possible, highly

complex shapes can be produced in single operation, assembly of sub-components can be avoided.

Selection of machine and material, setting of machine

parameters and proper product and mould design are important factors to achieve reproducible planned quality.

The process defines all the three dimensions of the

article quite accurately.

Advances in machinery, moulds and materials

continuously going on to produce articles with desired dimensions and properties.

Highly automated mass production is possible, highly

complex shapes can be produced in single operation, assembly of sub-components can be avoided.

Selection of machine and material, setting of machine

parameters and proper product and mould design are important factors to achieve reproducible planned quality.

Injection Moulding Applications Injection Moulding Applications

House hold Articles like

bucket, mugs, boxes etc.

House hold Articles like

bucket, mugs, boxes etc.

Appliances like TV,

transistor, computer cabinets, washing machine parts, etc.

Appliances like TV,

transistor, computer cabinets, washing machine parts, etc.

Injection Moulding Applications Injection Moulding Applications

Automotive components

like bumper, instrument panel, interior trims, handles etc.

Automotive components

like bumper, instrument panel, interior trims, handles etc.

Injection Moulding Applications Injection Moulding Applications

Furniture - moulded

chairs, tables, stools etc.

Luggage - shells of

bags

Furniture - moulded

chairs, tables, stools etc.

Luggage - shells of

bags

Injection Moulding Applications Injection Moulding Applications

Injection Moulding process Injection Moulding process

Compound containing additives like filler, colourant

• etc. or material granules blended with masterbatch

granules added to hopper of machine.

Material melted between revolving screw of certain

geometry and cylinder heated externally.

Molten material pumped into mould which defines

shape and size.

Material cooled and ejected from mould. Cyclic process with cycle times now reduced to less

than one minute.

Compound containing additives like filler, colourant

• etc. or material granules blended with masterbatch

granules added to hopper of machine.

Material melted between revolving screw of certain

geometry and cylinder heated externally.

Molten material pumped into mould which defines

shape and size.

Material cooled and ejected from mould. Cyclic process with cycle times now reduced to less

than one minute.

Injection Moulding process - Schematic Injection Moulding process - Schematic

Injection moulding Machines Injection moulding Machines

Machine choice depends on the article to be

moulded, the size of mould, rate of production etc.

Main specifications include clamping force in tonnes,

plasticizing capacity, shot capacity etc.

The machine can be manual or automatic. The controls include temperature of barrel and

nozzle, the shot weight, the injection speed (time), injection pressure, hold-up pressure, cooling time etc.

The mould temperatures also can be controlled by

cooling/ heating.

Machine choice depends on the article to be

moulded, the size of mould, rate of production etc.

Main specifications include clamping force in tonnes,

plasticizing capacity, shot capacity etc.

The machine can be manual or automatic. The controls include temperature of barrel and

nozzle, the shot weight, the injection speed (time), injection pressure, hold-up pressure, cooling time etc.

The mould temperatures also can be controlled by

cooling/ heating.

Moulds for injection moulding Moulds for injection moulding

Two halves of mould are clamped on machine

platens.

The mould consist of major parts/systems such as :

− Cavity and core to define article geometry − Material delivery system consisting of sprue, runners

and gate

− Article ejection mechanism − Additional cores - movable and non movable to define

the holes and openings in articles etc.

− Ejection system push-back mechanism − Sprue locking mechanism (cold slug well) to facilitate

sprue and runner material removal

Two halves of mould are clamped on machine

platens.

The mould consist of major parts/systems such as :

− Cavity and core to define article geometry − Material delivery system consisting of sprue, runners

and gate

− Article ejection mechanism − Additional cores - movable and non movable to define

the holes and openings in articles etc.

− Ejection system push-back mechanism − Sprue locking mechanism (cold slug well) to facilitate

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

stage is inflated against the cool surfaces of mould.

The articles obtained are hollow containers and can

have necks with threads to facilitate closing by caps and lids.

Intricate shapes such as fuel tanks in modern

automobiles, washing ware bottles can be attained.

The mould consists of two halves, in the opening of

the container- usually the neck- a blowing pin is used to blow air.

The article thickness is not uniform but can be

brought close to uniformity by programmable parisons etc.

A process in which polymer in molten or rubbery

stage is inflated against the cool surfaces of mould.

The articles obtained are hollow containers and can

have necks with threads to facilitate closing by caps and lids.

Intricate shapes such as fuel tanks in modern

automobiles, washing ware bottles can be attained.

The mould consists of two halves, in the opening of

the container- usually the neck- a blowing pin is used to blow air.

The article thickness is not uniform but can be

brought close to uniformity by programmable parisons etc.

Applications of blow moulding Applications of blow moulding

Bottles Containers air ducts in auto-AC

systems

Intricate shape closed

containers like auto-fuel tanks

clear medicinal bottles Baby feeding bottles Bottles Containers air ducts in auto-AC

systems

Intricate shape closed

containers like auto-fuel tanks

clear medicinal bottles Baby feeding bottles

Major types of Blow Moulding Major types of Blow Moulding

Major types of blow moulding are:

− Extrusion Blow moulding − Injection Blow moulding − Injection stretch moulding − Extrusion stretch blow moulding

Major types of blow moulding are:

− Extrusion Blow moulding − Injection Blow moulding − Injection stretch moulding − Extrusion stretch blow moulding

Extrusion Blow Moulding Extrusion Blow Moulding

Molten cylinder - known as parison is extruded out of

the die of extruder - continuously or intermittently

The parison is clamped in two halves of the mould The neck of the container gets defined by blowing pin,

which blows air.

The Polymer gets blown to conform to the geometry

defined by the mould halves.

By having multi-station process using more moulds

rate of production can be high

The parison thickness can be varied by parison

programming through die and thereby thickness can be more uniform.

Molten cylinder - known as parison is extruded out of

the die of extruder - continuously or intermittently

The parison is clamped in two halves of the mould The neck of the container gets defined by blowing pin,

which blows air.

The Polymer gets blown to conform to the geometry

defined by the mould halves.

By having multi-station process using more moulds

rate of production can be high

The parison thickness can be varied by parison

programming through die and thereby thickness can be more uniform.

Extrusion Blow moulding schematic Extrusion Blow moulding schematic

Injection Blow Moulding Injection Blow Moulding

The hot parison is injection moulded onto a blowstick. The blowstick is transferred with the hot parison to

blow mould defining the container geometry

Parison is blown to obtain the desired shape. The control on weight and dimensions is more

accurate than in extrusion blow moulding.

The hot parison is injection moulded onto a blowstick. The blowstick is transferred with the hot parison to

blow mould defining the container geometry

Parison is blown to obtain the desired shape. The control on weight and dimensions is more

accurate than in extrusion blow moulding.

Injection Blow Moulding - Schematic Injection Blow Moulding - Schematic

Injection Stretch Blow Moulding Injection Stretch Blow Moulding

Injection moulded preforms are heated and stretched

in two directions (biaxially)

Longitudinal stretching by telescopic mandrel and

circumferential by blowing

Lighter moulding with adequate rigidity obtained Containers with clarity and gloss Reduced permeability to gases (useful for Coke,

Pepsi etc).

Containers with greater precision in dimensions. Injection moulded preforms are heated and stretched

in two directions (biaxially)

Longitudinal stretching by telescopic mandrel and

circumferential by blowing

Lighter moulding with adequate rigidity obtained Containers with clarity and gloss Reduced permeability to gases (useful for Coke,

Pepsi etc).

Containers with greater precision in dimensions.

Injection Stretch Blow moulding

• Schematic

Injection Stretch Blow moulding

• Schematic

Extrusion Stretch Blow Moulding Extrusion Stretch Blow Moulding

The preform bottle is extrusion blow moulded Preform bottle temperature brought to suitable pliable

temperature

Transferred to the final mould Stretched to desired shape by extension of blowpin

and by blowing air.

The preform bottle is extrusion blow moulded Preform bottle temperature brought to suitable pliable

temperature

Transferred to the final mould Stretched to desired shape by extension of blowpin

and by blowing air.

Extrusion Stretch Blow Moulding Schematic Extrusion Stretch Blow Moulding Schematic

Rotational Moulding Rotational Moulding

Useful to prepare hollow article of any size and shape Well known example - Syntex tanks Polymer in form of powder fed to a mould. Mould is made to rotate around two axes Mould heated while rotating so that the material melts

and is getting forced to mould walls by centrifugal force.

Mould cooled and article taken out. Useful to prepare hollow article of any size and shape Well known example - Syntex tanks Polymer in form of powder fed to a mould. Mould is made to rotate around two axes Mould heated while rotating so that the material melts

and is getting forced to mould walls by centrifugal force.

Mould cooled and article taken out.

Rotational Moulding - Examples Rotational Moulding - Examples

Water tanks Fuel tanks for

tractors

Hollow articles

which can be assembled - e.g. Bus Stop at Reliance Jamnagar Colony, benches etc.

Water tanks Fuel tanks for

tractors

Hollow articles

which can be assembled - e.g. Bus Stop at Reliance Jamnagar Colony, benches etc.

Rotational Moulding schematic Rotational Moulding schematic

Compression Moulding Compression Moulding

Mainly used for thermosettings Starting material - compounded thermosetting resin. Physical form - solid powder (Moulding powder),

semisolid dough (Dough moulding compound), compound in form of sheet (sheet moulding compound)

Used to make electrical switches, ash-trays, electrical

connectors, shallow flat articles like auto-body panels etc.

Mainly used for thermosettings Starting material - compounded thermosetting resin. Physical form - solid powder (Moulding powder),

semisolid dough (Dough moulding compound), compound in form of sheet (sheet moulding compound)

Used to make electrical switches, ash-trays, electrical

connectors, shallow flat articles like auto-body panels etc.

Compression Moulding Compression Moulding

The compound placed in two halves of mould. Mould halves fixed to platens of vertical hydraulic

press

Material presses at high pressure while heating. Volatiles removed by breathing (releasing pressure

and again applying pressure.

Article ejected by ejection system The cycle times are large - due to cyclic heating and

cooling.

The compound placed in two halves of mould. Mould halves fixed to platens of vertical hydraulic

press

Material presses at high pressure while heating. Volatiles removed by breathing (releasing pressure

and again applying pressure.

Article ejected by ejection system The cycle times are large - due to cyclic heating and

cooling.

Compression Moulding Schematic Compression Moulding Schematic

Transfer Moulding Transfer Moulding

Process intermediate to compression and injection

moulding

Suitable to moulding around metallic inserts on which

high pressure cannot be applied.

Material heated in transfer pot, and then pushed

through runner and hate into heated mould.

The pressure on material is indirect by ram in the

transfer pot.

Process intermediate to compression and injection

moulding

Suitable to moulding around metallic inserts on which

high pressure cannot be applied.

Material heated in transfer pot, and then pushed

through runner and hate into heated mould.

The pressure on material is indirect by ram in the

transfer pot.

Transfer Moulding schematic Transfer Moulding schematic

FRP Moulding Processes FRP Moulding Processes

Lay-up techniques - Uses one part of mould cayity or

punch.After application of release agent, layers of Coloured gel coat and glass mat and resin are

• applied. The Resins solidify at Room Temperature by

chemical reaction, Article ejected.

Resin Transfer Moulding - Glass mat layed in a

mould, mould closed, catalysed resin pumped in, mould heated to effect solidification of article, Mould

• pened to remove article. Higher glass content so

higher strength possible.

Filament winding - Foe cylindrical articles like storage

• tanks. Glass rovings wound on a collapsible mandrel.

Rovings may be preimpregnated or resin may be applied after winding. After solidification, mandrel collapsed to remove article.

Lay-up techniques - Uses one part of mould cayity or

punch.After application of release agent, layers of Coloured gel coat and glass mat and resin are

• applied. The Resins solidify at Room Temperature by

chemical reaction, Article ejected.

Resin Transfer Moulding - Glass mat layed in a

mould, mould closed, catalysed resin pumped in, mould heated to effect solidification of article, Mould

• pened to remove article. Higher glass content so

higher strength possible.

Filament winding - Foe cylindrical articles like storage

• tanks. Glass rovings wound on a collapsible mandrel.

Rovings may be preimpregnated or resin may be applied after winding. After solidification, mandrel collapsed to remove article.

Hand lay-up techniques Hand lay-up techniques

Resin Injection Process Resin Injection Process

Filament Winding Filament Winding

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