Polymer Forming Processes

Prepared byAssociate Prof. Mohamed Ahmed Awad

Cairo, 2014

Polymer Forming Processes

Raw Materials

Polymer Products

• Extrusion

• Injection

• Blow

• Compression

• Vacuum Moulding

Extrusion Animation

5

Prepared by Dr. Mohamed Ahmed Awad

Extrusion

6

Prepared by Dr. Mohamed Ahmed Awad

Injection moulding Animation

7

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Injection Molding

8

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Blow moulding Animation

9

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Extrusion blow-molding

10

Prepared by Dr. Mohamed Ahmed Awad

Blow moulding Steps

Extruderair injector

Part isremoved

Airblowninto

parison

Moldhalvesclose

Moltenparison isextruded

Extruderair injector

parison

Compression mouldinganimation

12

Prepared by Dr. Mohamed Ahmed Awad

Compression Molding

13

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14

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Vacuum Forming

16

Prepared by Dr. Mohamed Ahmed Awad

Review QuestionsReview Questions

Describe the polymerextrusion process Plastic granules are fed from a hopper on to a

rotating Screw. The screw forces the plastic through a heated

tube where it becomes molten before beingforced under pressure through a die.

The die contains a hole whose shapecorresponds to that of the required Article.

As it leaves the die, the 'extrusion' is cooled in awater bath or In jets of air.

Prepared by dr. Mohamed Ahmed Awad١٩

Plastic granules are fed from a hopper on to arotating Screw.

The screw forces the plastic through a heatedtube where it becomes molten before beingforced under pressure through a die.

The die contains a hole whose shapecorresponds to that of the required Article.

As it leaves the die, the 'extrusion' is cooled in awater bath or In jets of air.

Draw the Extrusion machine

Prepared by dr. Mohamed Ahmed Awad٢٠

Describe the polymer formingusing blow molding process

The required material is extruded Air is blown into a section of extruded

plastic tube, causing it to expand andtake up the shape of the mould.

The mould is opened The part is removed.

Prepared by dr. Mohamed Ahmed Awad٢١

The required material is extruded Air is blown into a section of extruded

plastic tube, causing it to expand andtake up the shape of the mould.

The mould is opened The part is removed.

Blow Molding steps

Extruderair injector

Part isremoved

Airblowninto

parison

Moldhalvesclose

Moltenparison isextruded

Extruderair injector

parison

Prepared by dr. Mohamed Ahmed Awad٢٣

Describe the polymer injectionmolding process An injection molding machine is similar to that

used for extrusion. The screw is moved backwards, as it rotates,

until a measured quantity of plastic is at positionA in the diagram.

The screw is then driven forwards by ahydraulic ram, forcing the molten plastic into themould.

The mould consists of two or more parts whichfit together forming a cavity of the requiredshape.

After a short time the mould can be opened andthe molding removed. The complete cycle canthen be repeated.

Prepared by dr. Mohamed Ahmed Awad٢٤

An injection molding machine is similar to thatused for extrusion.

The screw is moved backwards, as it rotates,until a measured quantity of plastic is at positionA in the diagram.

The screw is then driven forwards by ahydraulic ram, forcing the molten plastic into themould.

The mould consists of two or more parts whichfit together forming a cavity of the requiredshape.

After a short time the mould can be opened andthe molding removed. The complete cycle canthen be repeated.

Prepared by dr. Mohamed Ahmed Awad٢٥

Describe the Compressionmolding In compression molding, huge forces are

used to squeeze polymer into moulds.

The polymer can be in the form of apowder or 'slug'.

Compression molding is used forthermosetting plastics.

Prepared by dr. Mohamed Ahmed Awad٢٦

In compression molding, huge forces areused to squeeze polymer into moulds.

The polymer can be in the form of apowder or 'slug'.

Compression molding is used forthermosetting plastics.

Prepared by dr. Mohamed Ahmed Awad٢٧

Describe the Vacuum molding

This processes is used to make articlesfrom thermoplastic sheet.

A heater then raises the temperature ofthe sheet until it becomes soft

Finally, air is evacuated from beneaththe sheet, which allows the normal'outside' air pressure to push down onthe softened sheet, forcing it to take upthe shape of the mould.

Prepared by dr. Mohamed Ahmed Awad٢٨

This processes is used to make articlesfrom thermoplastic sheet.

A heater then raises the temperature ofthe sheet until it becomes soft

Finally, air is evacuated from beneaththe sheet, which allows the normal'outside' air pressure to push down onthe softened sheet, forcing it to take upthe shape of the mould.

Prepared by dr. Mohamed Ahmed Awad٢٩