Project report on injection molding machine

Project report on injection molding Project report on injection molding machinemachine

By Amol Jalinder Torane,By Amol Jalinder Torane,Diploma in Mechanical Engineering,Diploma in Mechanical Engineering,

33rdrd year, year,From A.I.S.S.M.S Polytechnic From A.I.S.S.M.S Polytechnic

college, near Kennedy road.college, near Kennedy road.

Injection MoldingInjection Molding Injection molding is a process in which raw Injection molding is a process in which raw

material in the form of granules is feeded material in the form of granules is feeded in to the hopper and plasticized by a in to the hopper and plasticized by a reciprocating screw with heat and injected reciprocating screw with heat and injected into the close mold to get the optimum into the close mold to get the optimum shape of the required partshape of the required part

Materials such as polystyrene, nylon, Materials such as polystyrene, nylon, polypropylene and polythene can be used polypropylene and polythene can be used in a process called injection molding.in a process called injection molding.

Process of injection moldingProcess of injection molding

Injection molding machine Injection molding machine is separated in two units is separated in two units

namely..namely.. Injection unit :-Injection unit :- Injection unit can be described in four general steps Injection unit can be described in four general steps

regardless of the type of machine used..,regardless of the type of machine used.., 1. Powder or pelletized polymer is loaded and heated 1. Powder or pelletized polymer is loaded and heated

to the molten stateto the molten state 2. Under pressure, the molten polymer is forced into a 2. Under pressure, the molten polymer is forced into a

mold through an opening called a spruemold through an opening called a sprue 3. The pressurized material is held in the mold until it 3. The pressurized material is held in the mold until it

solidifies.solidifies. 4. The mold is opened and the part removed by 4. The mold is opened and the part removed by

ejector pins.ejector pins.

Clamping unit:-Clamping unit:- The clamping unit must be able to keep the mold The clamping unit must be able to keep the mold

halves closed during the pressurized injection of plastic halves closed during the pressurized injection of plastic and not allow flashing.and not allow flashing.

Common clamping mechanisms are direct hydraulic Common clamping mechanisms are direct hydraulic clamping and mechanical toggle clamps, actuated by clamping and mechanical toggle clamps, actuated by hydraulic cylindershydraulic cylinders

Toggle clamps make use of mechanical advantage but Toggle clamps make use of mechanical advantage but are opened and locked by use of a hydraulic cylinderare opened and locked by use of a hydraulic cylinder

Today, many injection molding machines use direct Today, many injection molding machines use direct hydraulic clamping since it uses fewer moving parts hydraulic clamping since it uses fewer moving parts and is reliable and highly controllableand is reliable and highly controllable

The methods by which molds are attached to clamping The methods by which molds are attached to clamping unit include screw and bolt fixtures, key rods and unit include screw and bolt fixtures, key rods and vacuum to hold the mold, magnetic force and friction or vacuum to hold the mold, magnetic force and friction or a combination of these.a combination of these.

Toggle and direct hydraulic Toggle and direct hydraulic clampsclamps

Plastic and its types used in Plastic and its types used in molding operationmolding operation

A plastic material is any of a A plastic material is any of a wide range of synthetic or semi-wide range of synthetic or semi-synthetic organic solids that are synthetic organic solids that are moldable.moldable.

Plastics are typically organic Plastics are typically organic polymers of high molecular polymers of high molecular mass, but they often contain mass, but they often contain other substance.other substance.

PlasticsPlastics

Formed by heat

Thermoplastic plastics:

Soften when heated

Can be reheated and reshaped

Mostly recyclable

Made of long polymer chains

with few cross links

There are two main groups of plastics: thermosetting plastics

thermoplastic plastics. What does the word ‘plastic’

mean?

The word ‘plastic’ means ‘easily shaped or moulded’.

Initially set by heat

Thermosetting plastics:

Cannot be reshaped once set

Strong and durable Common in powder or resin forms

Consist of polymer chains with strong

bonds between each chain

What items do you have in your possession that are made of plastic? Are they made from thermoplastic

or thermosetting plastics?

Plastics Plastics

individual monomer molecule individual monomer molecule

Thermoplastic plastics are made of long chains of polymers which don’t cross over very often. When heated, the molecules slip easily over one another.

Thermosetting plastics also have lots of long chain molecules, but there are links between them. These cross links prevent the molecules from moving over one another.

PlasticsPlastics

The majority of common plastics are thermoplastics.

Thermoplastics can be heated and reshaped because of the ways in which the molecules are joined together.

This can be repeated many times (as long as no damage is caused by overheating).

Heat

Cool

Harden Soften

Thermoplastic plasticsThermoplastic plastics

Thermoplastic plastics Thermoplastic plastics

They are heated and moulded during manufacture.

Once cooled, they will not soften again when heated. This breaks the potentially unending cycle that thermoplastic plastics are capable of.

If heated too much, they burn.

Thermosetting plastics are those which are set with heat and have little elasticity. Once set, they cannot be reheated and reformed.

Heat

Cool

Harden Soften

Burn

Thermosetting plasticsThermosetting plastics

Thermosetting plastics Thermosetting plastics

Here are some common products made from thermoplastics. Can you say which type of thermoplastic each one is made of?

Acrylic

High densitypolythene

ABS

Low density polythenePolypropylene

Uses of plastics Uses of plastics (thermoplastics)(thermoplastics)

Polystyrene

Thermosets have different qualities to thermoplastics. Can you say which thermoset each of these products is made from?

Melamine formaldehyde Urea

formaldehyde

GRP

Phenol formaldehyde

Epoxyresin

Uses of plastics Uses of plastics (thermosets)(thermosets)

Injection MoldingInjection Molding Materials such as polystyrene, nylon, Materials such as polystyrene, nylon,

polypropylene and polythene can be used polypropylene and polythene can be used in a process called injection molding.in a process called injection molding.

These are thermoplastics - this means These are thermoplastics - this means when they are heated and then pressured when they are heated and then pressured in a mould they can be formed into in a mould they can be formed into different shapes. A simple diagram of an different shapes. A simple diagram of an injection molding machine is shown injection molding machine is shown below. below.

Injection MoldingInjection Molding

Operating principle of Operating principle of injection molding machineinjection molding machine

A similar desk organizer can be manufactured A similar desk organizer can be manufactured through injection molding. With this process through injection molding. With this process molten plastic is injected into a steel mould. The molten plastic is injected into a steel mould. The steel mould made to great accuracy and it can be steel mould made to great accuracy and it can be reused thousands of times. It is made in two reused thousands of times. It is made in two halves so that when the molten plastic has cooled, halves so that when the molten plastic has cooled, the two parts can be separated and the plastic the two parts can be separated and the plastic desk organizer removed. Thermoplastics such as desk organizer removed. Thermoplastics such as polystyrene, nylon, polypropylene and polythene polystyrene, nylon, polypropylene and polythene are ideal plastics for this type of manufacturing are ideal plastics for this type of manufacturing process.process.

Although the desk organizer is Although the desk organizer is manufactured in one piece, the tubes look manufactured in one piece, the tubes look as if they are separate. However, if you as if they are separate. However, if you look closely they are joined by small look closely they are joined by small ‘fillets’ of plastic. These can be cut, if each ‘fillets’ of plastic. These can be cut, if each part of the desk organizer is to be used part of the desk organizer is to be used separately, or the client wants to split the separately, or the client wants to split the large desk organizer into a number of large desk organizer into a number of smaller pieces (by cutting with a scissors smaller pieces (by cutting with a scissors or craft knife).or craft knife).



Stages of Injection moldingStages of Injection molding Stage Stage 1 1 Granulated or powdered thermoplastic plastic is fed from a Granulated or powdered thermoplastic plastic is fed from a hopper hopper into the into the

Injection Molding machine.Injection Molding machine.

Stage 2Stage 2The Injection Molding machine consists of a hollow steel barrel, containing a The Injection Molding machine consists of a hollow steel barrel, containing a rotating screw (rotating screw (Archemidial ScrewArchemidial Screw). The screw carries the plastic along the ). The screw carries the plastic along the barrel to the mould.barrel to the mould.HeatersHeaters surround the barrel melt the plastic as it travels along the barrel. surround the barrel melt the plastic as it travels along the barrel.

Stage 3Stage 3The screw is forced back as the melted plastic collects at the end of the The screw is forced back as the melted plastic collects at the end of the barrel.barrel.Once enough plastic has collected a Once enough plastic has collected a hydraulic ramhydraulic ram pushes the screw pushes the screw forward injecting the plastic through a forward injecting the plastic through a spure spure into a mould cavity. into a mould cavity. The mould is warmed before injecting and the plastic is injected quickly to The mould is warmed before injecting and the plastic is injected quickly to prevent it from hardening before the mould is fullprevent it from hardening before the mould is full

Stages of Injection Stages of Injection mouldingmoulding

Stage 4Stage 4

Pressure is maintained for a short time (Pressure is maintained for a short time (dwell dwell timetime) to prevent the material creeping back during ) to prevent the material creeping back during setting setting (hardening). This prevents shrinkage and (hardening). This prevents shrinkage and hollows, therefore giving a better quality product.hollows, therefore giving a better quality product.The moulding is left to cool before removing The moulding is left to cool before removing ((ejectedejected) from the mould. The ) from the mould. The mouldingmoulding takes on takes on the shape of the mould cavity.The image below the shape of the mould cavity.The image below shows an an shows an an Injection Moulding machine.Injection Moulding machine.

Process illustrationProcess illustration 11. The plastic is fed in granular form into a . The plastic is fed in granular form into a

'hopper' that stores it. 'hopper' that stores it. 22. A large thread is turned by a motor which . A large thread is turned by a motor which

feeds the granules through a heated section. feeds the granules through a heated section. 33. In this heated section the granules melt and . In this heated section the granules melt and

become a liquid and the liquid is fed into a mould. become a liquid and the liquid is fed into a mould. 44. Air is forced into the mould which forces the . Air is forced into the mould which forces the

plastic to the sides, giving the shape of the bottle.plastic to the sides, giving the shape of the bottle. 55. The mould is then cooled and is remove. The mould is then cooled and is remove

Injection Molding MachineInjection Molding Machine

Mounting the mould and setting the clamping unit

set mould height on the machine with the clamping unit closed

check clamping devices fix mould securely to the lifting tackle, ensuring that the

two mould halves remain together, if necessary by bolting

lock mould and thoroughly tighten up clamping bolts set clamping force at desired level set mould safety device: low pressure and high pressure set mould opening stroke, with damping. set ejectors

Molding TerminologiesMolding Terminologies Pattern: A sample or prototype to make some Pattern: A sample or prototype to make some

design as is made by a dye.design as is made by a dye. Mold: A Mold: A moldmold or or mouldmould is a hollowed-out block is a hollowed-out block

that is filled with a liquid like plastic, glass, metal, that is filled with a liquid like plastic, glass, metal, or ceramic raw materials. or ceramic raw materials.

Moldmaker: The manufacturer who makes Moldmaker: The manufacturer who makes the molds is called moldmaker .the molds is called moldmaker .

Release Agent:A release agent is typically Release Agent:A release agent is typically used to make removal of the hardened/set used to make removal of the hardened/set substance from the mold easier.substance from the mold easier.

Setting the injection unit

after having heated up the cylinder, set nozzle contact force make sure the mould is closed initially set material feed somewhat lower than the required shot

weight set the position for change-over to hold-on pressure based on safety

side plasticize stepwise under manual control, while observing how the

material feeds: this should be consistent and not jerky movements after a short pause, purge out manually and check the melt

temperature set injection speed and injection pressure to average values

Setting the machine controls

set the operational selector switch to manual

set injection time, after-pressure time and pause time initially somewhat longer than necessary, then optimize

them after a few shot

Starting the injection processWhen all settings have been checked, switch over from

‘manual’ to ‘semi-automatic’ mode. In general the settings must be optimized after several shots. Take following steps:

increase or reduce metering optimize injection speed observe the material cushion in front of the screw check pressure build-up during injection check cooling time and if possible shorten it set screw r.p.m. to a low value: plastification time should

be slightly shorter than cooling time

Starting the injection process check mould locking force harmonize machine movements to obtain a better balance of

speeds, sequence and damping if visually acceptable moldings are being produced, check quality where necessary, optimize and store the various functions record machine setting data ensure that moldings are correctly taken out and transported away ensure quality control aim for a ‘fully-automatic’ machine cycle to ensure uniform molding

quality

The Injection Moulding-The Injection Moulding-MouldMould

A mould used for Injection Moulding may cost thousands of A mould used for Injection Moulding may cost thousands of pounds to produce however it does turn out to be economical as pounds to produce however it does turn out to be economical as many thousands of mouldings can be produced from a single many thousands of mouldings can be produced from a single mould. This results in the low cost of each moulding.mould. This results in the low cost of each moulding.It used to be the case that when a new type of casting was needed It used to be the case that when a new type of casting was needed a brand new a brand new diedie had to be made. Modern dies and moulds are had to be made. Modern dies and moulds are made from a number of made from a number of interchangeable partsinterchangeable parts. This allows the . This allows the shape of the mould to be altered.shape of the mould to be altered.The dies or moulds used in this process are made from The dies or moulds used in this process are made from alloy alloy stainless steelstainless steel. These special alloy steel moulds are made in a . These special alloy steel moulds are made in a number of parts to allow the mouldings to be easily removed.number of parts to allow the mouldings to be easily removed.These steel moulds are initially very expensive to make and are These steel moulds are initially very expensive to make and are suited to production in quantity where accuracy of size, shape and suited to production in quantity where accuracy of size, shape and surface finish is essential.surface finish is essential.

Injection Molding Injection Molding ApplicationsApplications

Injection molding is a manufacturing technique for Injection molding is a manufacturing technique for making parts from plastic material.making parts from plastic material.

Heated, fluid plastic is injected at high pressure into Heated, fluid plastic is injected at high pressure into a mold, which is the inverse of the desired shape. a mold, which is the inverse of the desired shape.

The steel or aluminum mold is machined with the The steel or aluminum mold is machined with the contours of the final product. contours of the final product.

Injection molding is used for create a variety of Injection molding is used for create a variety of parts, like plastic milk cartons, containers, bottle parts, like plastic milk cartons, containers, bottle caps, automotive dashboards, pocket combs, and caps, automotive dashboards, pocket combs, and most other plastic products available today. most other plastic products available today.

Injection Molding Applications Injection Molding Applications

Injection molding is the most common method of Injection molding is the most common method of part manufacturing. part manufacturing.

AC drives will commonly be used to power the AC drives will commonly be used to power the hydraulic oil pressure pump for operating the hydraulic oil pressure pump for operating the mold works of an injection-molding machine. mold works of an injection-molding machine.

Servo drives can be used to operate the injection Servo drives can be used to operate the injection screw, as precision control is often required for screw, as precision control is often required for the injection step. the injection step.

Significant energy savings are often realized by Significant energy savings are often realized by replacing hydraulics with electric drive systems replacing hydraulics with electric drive systems on injection molding machines.on injection molding machines.

Thank you…Thank you…