Metallic filters can be manufactured through powder metallurgy techniques like cold isostatic pressing and sintering metal powders. Common materials used include stainless steel, titanium, and aluminum alloys. Metallic filters have applications in filtration, heat exchange, sound absorption, energy absorption, and medical implants due to their uniform porosity, mechanical strength, and corrosion resistance. Key advantages over solid metals include lower density, higher surface area, and ability to form complex 3D shapes.

1. By: Bahjat H. Sulaiman
Supervised by
Dr. Abdullah Akpolat
Metallic Filters

2. Metallic Filters

3. Metallic Filters

4. Metallic Filters
• Filters
In designing for PM porous metal parts,
generally, the performance functions are listed in
four groups:
*Filtration *Flow Control *Distribution *Porosity
- Controlled porosity is employed in the
manufacture of metal filters and diaphragms.

5. Metallic Filters
Different shapes and sizes

6. Metallic Filters
*Materials Used for Filters
The most commonly used filter elements
are made of bronze copper, nickel, bronze,
stainless steel, Titanium and 'Monel‘
*Price of metallic filters from 7$ to 12000$
per one kg .

7. Metallic Filters
Preparing powder:
 One of the most using water- atomized
stainless steel powdered
- binder assisted extrusion are used to
produce large, flat sheets and seamless
cylinders.
- Powders are also mixed with binders and
pore-forming agents to increase porosity.

8. Manufacturing Technology
Filter elements are produced by cold isostatic pressing.
For the compaction process the metal powder is filled
into the compacting tool which is made of a solid steel
core and oversized outer rubber sleeve (specially
designed furnaces).
After sintering, regardless of micron size, the separate
grain structure of the original powdered metal becomes
fully interlinked to form a rigid part. Sintering gives the
high porosity material the shape, stability and property
of a strong metal component.

9. Manufacturing Technology
*By sealing this assembly and immersing it in a liquid inside
a vessel that then is pressurized, a pressed part will be
obtained.
*Most importantly, this part will have uniform porosity with
homogeneous, physical characteristics and properties over
the total part.
*This processing method allows the manufacture of seamless
filter elements up to 1500 mm length and 320 mm diameter
with various wall thicknesses.
*compared to other manufacturing technologies is that
smaller quantities also can be economically produced
*Welds thereby are eliminated and the mounting of such filter
cartridges and filter tubes in the filter apparatus is very much
simplified.

10. Open-cell metal Filters
Closed-cell metal Filters

12. Designing of metallic filters:
Porous PM parts are capable of extremely fine degrees of filtration.
The subject of absolute vs. nominal filtration or micron ratings is
too complex to be treated; it is so complex, in fact, that much of
the filter design in PM porous media on new applications has been
performance oriented (actual test of samples) rather than based on
theoretical design data.
In designing for filtration, a close relationship between part
designer and PM vendor is particularly important, because
pressure drop is a function not only of the PM structure, but of the
working area and thickness as well as.

13. Introduction
Metallic Filters Production Methods:
Producing Porous Materials and
Filters
The filter profile is formed by a loose
packing of the powder in the mould
and the inherently poor compressibility
of spheres is no disadvantage.
Where products are required to have
limited or localised porosity,
conventional pressing is necessary
and irregularly shaped particles are
more suitable.
Prod. stages
Characteristic
s
Applications
Porosity Effect
Prod. Methods

14. Porosity --- Strength
Behavior of metal filter under compression
Introduction
Prod. Methods
Prod. Stages
Applications
Characteristic
s
Porosity
Effect

15. Made from Al
Metallic Filters Characteristics
, C, Cu, Ti, Si, based Alloys
Introduction
Prod. Methods
Prod. Stages
Applications
Characteristic
s
Porosity
Effect

16. Metallic Filters Characteristics
Advanced technology
of manufacturing
High
Cost
High
Porosi
ty
Reduced
conductiv
ity
Smaller
thermal
expansio
n
coefficientCorrosion
Resistan
ce
OTHER
• Resistance to harsh environments (high temperatures, corrosion
& humidity depending on metals and ceramics used)
• Good impact energy absorption
• Great noise attenuation
• Recyclable

17. Features:
• Metal filters of various geometric shapes are suitable for
filtration gases and liquids
• Sintered metal filters have uniform structure, high mechanical
strength and excellent high temperature resistance
• Filters can be put together by soldering or gluing
• Filter efficiency can be regulated by grain size of used powder
• The service life can be prolonged by cleaning and
regenerating process
• Shape, size and distribution of the powder particles are
selected based on the specifications of the filter to be
produced.
• For a given porosity, the quality of a filter is determined by it’s
permeability which depends on porosity, pores, surface area,
tortuosity of the pore space.

18. Features
Some features
(sintered stainless steel filters):
• Spherical gas-atomized powders because of their more
uniform porosities, topologies, and smoother pore surfaces –
provide more controlled and superior permeability and filtration
efficiencies.
• Porosities for stainless steel filters range from approximately
20% to 70%, with mean pore sizes from 1 to 165µm.

19. Testing of Porous Sintered Materials:
• There is many standard tests.
• The best test for the designer to specify is a (performance
test),
• This is particularly important for flow control elements whose
function depends not only on the PM part but also on its
method of assembly.
• sample components, pre-assembled in their housings, are
tested under simulated performance conditions.
• Flow rate and pressure drop are measured

20. • When it is difficult to collect all of the gas from a
PM part (for example, a long tube).
• Parts used in time delay applications may be
tested for elapsed time under simulated conditions
rather than in steady state flow.

21. • “German” has shown for more complete
description of flow rate in (stainless steel
filters)
It is necessary to take into account inertial
energy losses of the flow medium arising from
changes because of passing through tortuous
pore structure.

22. P: average pressure
ΔP: pressure drop within filter
Pm: pressure at Q
t: thickness
µ: dynamic viscosity of the gas
Q: flow rate
α0: viscous permeability coefficient
ρ: density of the gas
β: inertia permeability coefficient

23. Material of a filter
ISO standard
Measure pressure drop
&
volumetric flow rate
Procedures for
experimental determination
Viscous & inertial
permeability coefficients

24. Filter characteristics of 316 powder as a function of
porosity & sieve fraction
(a) viscous permeability coefficient.
(b) filter grade by glass bead test.

25. Shear strength of three
316L stainless steel as a
function of porosity

26. - With optimal sintering, the corrosion resistances of stainless
steel filters will follow those of optimally sintered structural
stainless steel parts, taking into account lower densities (in the
acidic environment, corrosion resistance declines with decreasing
density ‘increasing surface area’)
- St filters with superior flow efficiencies are made of St fibers
(porosity up to 90%)
- Particle size has no effect on shear strength.

27. • Benefits of metal filters
Main Properties:
• Shape-stability, i.e. self-supporting structural
elements suitable for high differential pressures and
pressure swings.
• Particularly good properties under compression,
vibration and changing conditions or with high
impulse pressures.
• High heat resistance and thermal stability up to 1,742
°F.
• High permeability with low pressure drop.
• Chemical resistance against acids and caustic
solutions in various ranges of pH.
• Back-flushing and easy cleaning with supersaturated
superheated steam, chemical solvents, thermal
processes and ultra-sonic baths.

28. Metallic Filters Applications
Introduction
Prod. Methods
Prod. Stages
Applications
Characteristic
s
Porosity
Effect

29. Metallic Filters Applications
*Sandwich cores Metal filter have low density with good shear
and
fracture strength.
*Strain isolation Metal filter can take up strain mismatch by
crushing at controled pressure
*Mechanical damping The damping capacity of metal filter
larger
than that of solid metals
*Vibration control metal filter panels have higher natural
flexural
vibration frequencies than solid sheet of the same
mass per unit area
*Acoustic absorption Reticulated metal filter have sound-
absorbing
capacity
*Energy management: Metal filter have exceptional ability to

30. Metallic Filters Applications
*Energy management compact or light energy absorbers
*Packaging with high-temperature
*Artificial wood (furniture, wall panels)
*Thermal management heat exchangers refrigerators
*Thermal management flame arresters
*Thermal management heat shields
*Consumable cores for castings
*Biocompatible inserts
*Electrical screening
*Electrodes,
*Buoyancy

31. 1. High Absorption Of Impact Energy.
automobile industry
control collapse vibration
damping
.

32. 2. Sound Absorption,

33. 3-High Strength Applicationst
• Diamond orientation 304 stainless steel textile sandwich
panel with relative core density (12.6%).
• Tetrahedral structures are stacked node to node with an
interleaved planar hexagonal perforated layer

34. • Diamond orientation 304 stainless steel textile sandwich
panel with relative core density (12.6%).
• Tetrahedral structures are stacked node to node with an
interleaved planar hexagonal perforated layer
4-Mechanical Thermal Protection System(for Skin)
(For a hypersonic aircraft - 5 Mach Number)
Requirement : To withstand surface temperature of 1100oC
Ceramic wool of
thickness 40mm
Facing sheet – Ni alloy of
0.08 - .1mm
Core - Ni alloy of 4mm cell
size honeycomb structure
Core - Ti alloy of 4mm cell
size honeycomb structure
Facing sheet – Ti alloy of
0.3 - .4mm

35. 5. Electro-magnetic Shielding
Low Magnetic Permeability
6. Load Baring Parts
good mechanical properties :
strength - stiffness - low weight
Strength up to 100 kN both in the
normal and shear plane cheaper than
conventional honeycomb design)

36. 7. Filteration
Silicon carbide filter for hot
gases at rocket nozzle (high
temp. strength)
Sintered filter elements:
Five-layer sintered wire cloth can be made into different shape filter
elements, such as filter tube, cone-shape filter, filter baskets, cartridge
filters, disc filters, cup filters, cap filters, and filter plate.
- Generally these filters rating are from
0.2um to 200um, working temperature
from -200°C to 1000°C

37. 8. Heat Exchanger
• interconnected cells + a random orientation + high surface
area make metal filter ideal for
heat exchangers catalysts.
• pore-size of metal Filters results in heat removal
effectiveness

38. 9. Aluminium Filters
Sandwich panels
(AFS)

39. 10. Medical applications
Spongeous bone and metallic filter show
similar structures
• Ti (titanium) shows high
compatibility with tissue
• metal Filters is used as an
experimental prosthetic (an
artificial part) in animals.
• hole is drilled into the bone and
the metal Filters is inserted into
the hole drilled in the bone.
The pores allow the formation of
vascular system grow within the
area. More recently,
• orthopedic device manufacturers
have started producing devices
that use either metal filter
construction or metal Filters
coating to achieve the desire
level of Osseo integration.

40. 11. Separating / diffusing
Applications of powder metallurgy parts. Filters
can be used for diffusing or for separating.

41. • Catalyst separation and recovery
• Refinery applications
• Aerosol separation
• Fluidization
• Air bearings for polymer sheet production
• dampening
• Silent
• sensor protection
More applications:

42. Advances of Filters metal over
dense metal
• much stiffer than sheet at same mass
• manufacture of complex shapes (3D) possible
• cost
• elastic limit
• failure mode
• damage tolerance
• integration into system→ joining technology
• other aspects, e.g. mechanical, acoustic
electromagnetic
damping ...