Presentation on Powder Methods VIJAY 2008AMD2925.
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Transcript of Presentation on Powder Methods VIJAY 2008AMD2925.
Presentation on
Powder Methods
VIJAY2008AMD2925
Introduction Manufacturing process in which fine powder of
materials are-Blended or mixed,Compacted (pressed) in to required shape, size and surface
finish Sintered (heated) Controlled atmosphere to bond the contacting surfaces of
particles and to achieve required properties like strength, density etc.
High quality, complex parts to close tolerances in an economical manner (eliminating additional machining or finishing operations ).
Controlled degree of density, porosity, strength and other properties of material, with minimum waste
ApplicationsApplication Metals Uses
Abrasive Fe, Sn, Zn Cleaning, abrasive wheelsAerospace Al, Be, Nb Jet engine, heat shield
Automotive Cu, Fe, W Valve insert, bushing, gearsElectronic Ag, Au, Mo Diode heat sink
Joining Cu, Fe, Sn Solder, electrodeMagnetic Co, Fe, Zn Relay, magnets
Manufacturing Cu, Mn, W Dies, tools, bearingsNuclear Be, Ni, W Shielding, filters, reflector
Tungsten lamp filaments, oil-less bearings, automotive transmission
gears, electrical contacts, nuclear power fuel elements, aircraft brake
pads, jet engine components, printed circuit boards, explosives, welding electrodes, rocket fuels, etc [2]
Table1:- Application of powder methods [1]
Production of a component
1. Production of powder
2. Preparation of powder including blending and mixing
3. Compacting
4. Sintering 5. Post sintering treatment [3]
Production of Powder
1. Mechanical method (milling) Ball mills and roller mills Ferrous and non ferrous materials Brittle
Fig 1:- Ball mill
Image courtesy: - Ref. [4]
Production of Powder2. Electrolytic Deposition
Spongy or powdery state of metalSuitable conditions; composition and strength of the
electrolyte, temperature, current density, etcCopper, chromium and manganese powders Pure powder
Fig 2:- Electrolytic deposition Image courtesy: - Ref. [2]
Production of Powder3. Reduction of ores Iron powder
4. Atomisation Liquid metals – Orifice- Jet stream of gas, water, or
steam –Broken into fine particles To control particle size distribution-
Parameters; design and configurations of the jets, pressure and volume of the atomising fluid, thickness of the stream of metal, etc
Production of iron, tool steels, alloy steels, copper, brass, bronze and the low-melting-point metals, such as aluminium, tin, lead, zinc, cadmium powders. [2]
Fig 3:- Vertical gas atomization unit Image courtesy: - Ref. [5]
Preparation of powder Blending and MixingTo obtain desired properties and characteristics we
have to mix Powder of different materials -different grades and
sizes- different compositionLubricants and binders. Alloying elements
Fig 4:- Powder contents Image Courtesy: - Ref. [2]
Compacting Loose powder of material is compressed and densified –Green
compact- At room temp.
Mechanical, hydraulic and pneumatic presses.
Fig 5:- Compaction sequence
(1)Cycle start (2)Charge die with powder(3)Compaction begin(4) Compaction completed(5) Ejection of part(6) Recharging die
Image Courtesy: - Ref.[2]
Sintering Green compact is heated in a controlled atmosphere Below the melting point but high enough to permit solid
state diffusionHeld for sufficient time to permit bonding of the particlesSintering temperature range for iron-based alloys is
1100-1150°C and the time varies between 10 and 60 minutes, depending on the application [6]
Fig 6:- Sintering process Image Courtesy: - Ref. [7]
Post sintering treatments
Machining De-burring Joining Heat treatment Double Pressing Oil Impregnation
Advantages of the powder methods Complex shapes can be produced. Close dimensional accuracy with elimination
or reduction in machining. High production rate due to automation. Wide range of properties like density, porosity
and particle size can be obtained. No waste during fabrication. Highly skilled labour is not required. [8]
Disadvantages and limitations Pure metal powders are very expensive. Size of part produced is limited. Alloy powders are not easily obtained. Strength properties are lower than product
manufactured by convention way. Increased tendency to oxidation due t pores. Poor plastic properties like impact strength,
elongation etc. High pressure and severe abrasion involved in
process increase the die cost. [8]
References:-1. Manufacturing Engineering and Technology by Seropr
Kalpakjian and Steven R. Schmid , Chapter 17, Table 17.1 Page 461
2. http://www.turktoz.gazi.edu.tr3. Manufacturing Engineering Processes by Leo Alting, Chapter
9, Page 281-2994. http://www.ktf-split.hr/glossary/image/ball_mill.gif5. http://www.xstreamscience.org/H_Glaze/assets/Powder
%20Atomizer.gif6. http://www.substech.com7. http://www.azom.com/details.asp?ArticleID=1328. Elements of Workshop Technology by S.K. and A.K. Hajra
Choudhury, Chapter 12, Page 431-440.
Thank You…….