Cold isostatic pressing

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1. COLD ISOSTATIC
PRESSING

2. Isostatic Pressing
•COLD ISOSTATIC PRESSING (CIP) is a materials processing technique in which high pressure is applied to
metal powder in a sealed elastomer container shaped for the application.
•The powder is converted from a loose aggregate into a partially dense compact that has sufficient green
strength to permit careful handling and transfer to the following process operation.
•Compacting pressures range from 207 to 414 MPa (30 to 60 ksi), although pressures as high as 758 MPa (110
ksi) have been used.
•Compaction is performed at ambient temperature.
•The density of the loose powder poured into the elastomer moldis increased from 55 to 65% of theoretical,
a nominal range for uncompactedpowder, to 75 to 85% of the 100% theoretical density value of the metal
being processed.

3. Continue..
•The metal powder is compacted uniformly in all directions so that the
compact becomes an accurate scale down of the mould.-------uniform
density -------a homogeneous microstructure
•For this purpose the powder is sealed in a flexible envelope and the
assembly (mould-powder) is immersed in a fluid which is pressurized.
•There are virtually no residual stresses in the compacted material, because
there is no die wall friction.

4. Why Isostatic Pressing?
•To get uniform density and compaction.
•To make intricate shapes.
•To get objects with great dimensional tolerance.
•To get homogeneous structure.
•Figure1 shows the use of formers and use of containers with holes for
support purposes.

5. Cold Isostatic Process
Two methods are used ,
Method (I)
free mould or "wet bag" process
This is suited for
•batch scale production;
•the mould is filled and sealed outside the pressure vessel.
•After the mould is introduced in to the pressure vessel, it is completely immersed in the pressure medium, usually water containing
lubricating and corrosion-preventive additives;
•complex parts;
•research and prototype work;
•several moulds in one run-even with differing shape, i.e. parts of different sizes and shapes that require the same process parameters can be
pressed in the same cycle.

6. a) Powder fill by weight or volume.
b) Filling of the mould from the top.

7. c) Top lid put on the mould container.
d) Mould is placed inside the pressure vessel.

8. e) Top lid put on the pressure vessel after necessary
evacuation and filling with the pressurizing medium.
f) Top lid removed after required isostatic compaction for
removal of the mould.

10. Method (II)
Fixed mould or "dry bag" process
which is characterized by,
•envelope is permanently fixed into the pressure vessel,
•After the elastomeric mould is filled with powder, pressure is applied by
introducing pressurized oil between the fixed mould and the vessel wall,
•only one compact at a time is used,
•more simple shapes are made and
•more suited for mass production and faster production rates.

11. Schematic of equipment for dry-bag isostatic pressing.

12. Video About CIP Process

13. Advantages of Cold Isostatic Pressing
•Highest safety.
•Outstanding cycle life.
•Superior process control at all pressure levels.
•Programmable pressure distribution with good accuracy.
•Reduced mechanical stresses of processed materials.
•Lowest weight of the machine.
•Process optimization.
•Improved functionality.

14. Disadvantages of Cold Isostatic Pressing
•Slower than uniaxial pressing.
•Components may require post-processing.

15. Applications of Cold Isostatic Compaction
•Titanium e.g. hydraulic aircraft fittings using Ti powder and Al-V master alloy
powder.
•High-speed tool steels (e.g. cutting tools).
•Compacts with interior threads.
•Long hollow cylindrical filters (stainless steel and titanium powder).
•Large shapes from tungsten powder such as rocket nozzle.
•Tungsten and molybdenum blooms or slabs for further forging and/or rolling.

16. Cross-section of Molding Bag

17. Body Armor

18. Bag and Molding Core Pin

19. Bag and Pressing Mandrel

20. Tubes Made by Isostatic Pressing

21. Thank You!