Powder metallurgy &

Press working

Presented BY:- JAY KUMAR :- CUT120104139

Powder Metallurgypowder Metallurgy may be defined as The Art and science of producing metal powder and utilize them to make useable object . or Powder metallurgy is a branch of metallurgy which deals with the production of metal and non metal powders and subsequently manufacture of components by using these powders.

Process of powder metallurgy

Finished P/M parts

Sintering operation

Processing-compacting

Mixing & Blending

powder characteristics & Testing

Powder prodution

Producing metal powders

Various methods for manufacturing powders are -

1. Atomization 2. Reduction 3. Crushing 4. Milling 5. Shutting 6. Electrolysis.

1. Atomization :-The process of

conversion of molten metal into the spray of droplets that solidify into powder is called atomisationIt is an excellent means of producing metal powders from many of the low temperature metals such as lead, aluminium, zinc and tin

2. Reduction:- Reduction process

is carried out in an atmosphere controlled

furnace.

In reduction process, the compounds of

metals usually oxides like iron oxides are

reduced with CO/H2 at temperature below

melting point of metal

3. Crushing:-Process of passing the metal powders against two rollers so that the metal powders are crushed to required size.

4. Milling:-Milling is carried out by

using equipment’s such as ball mill, rod mill,

impact mill, disk mill etc. In ball milling,

material to be powdered is collected in a

container with a large number of hard steel

balls. These balls hit the material and break it

in powder form. 5. Shutting:-The process of pouring molten metal through a sieve or orifice and cooling by dropping into water is known as shutting.This process gives spherical or pear shaped powder particles.

6. Electrolysis:-In this method, an electrolytic cell is set up as shown in figure. The desired metal is made to act as anode.Anode slowly dissolves and gets deposited on the cathode from where the deposit is removed, washed and dried.

Mixing & BledingBlending : Mixing powder of the same chemical composition but different sizesMixing : Combining powders of different chemistries. Addition of lubricants coats the powders and reduces die wear and lowers pressure required for  pressing of powders.Mixing powders of different materialsObtaining uniform distribution of particle sizes.

Processing & compating

Compaction :- Pressing the powders into desired part shape as closely as possible to final dimensionsPowders are compacted using high pressure.Degree of pressure required depends upon- -Required density of final product -Ease with which powder particles will weld together.Compacting processes are - 1)Die pressing 2) Roll pressing 3) Extrusion

Sintering process Sintering is the Heat treatment process, to bond the metallic

particles, thereby increasing strength and hardness.

Sintering consists of heating pressed metal compacts in

batch or continuous furnaces to a temperature below the

melting point of material. Most metals are sintered at 70% to

80% of melting temperature.

Finishing OperationsA number of secondary and finishing operations can be applied after sintering, some of them are:Sizing :-cold pressing the sintered part to improve dimensional accuracy.Coining:- cold pressing to press details into its Surface.Impregnation :- oil fills the pores of the partInfiltration :- pores are filled with a molten metalHeat treating :- annealing can be done for stress relief in powder metallurgy part.Machining :-creates geometric features that cannot be achieved by pressing, such as threads, side holes, and other details

Some of product produce by powder metallurgy is given below:-

PRESS WORKINGPress working may be defined as, a manufacturing process by which various components are made. It is type of forging which utilize squeezing preesure of a press in shaping a metal piece is known as press forging. The machine used for press working is called a press.Generally two types of press is used mechanical press & Hydraulic press.

The main features of a press are:-

A frame which support a ram or a slide and a bed, a source of mechanism for operating the ram in line with and normal to the bed.The ram is equipped with suitable punch or punches and a die block is attached to the bed.A stamping is produced by the downward stroke of the ram when the punch moves towards and into the die block.The punch and die block assembly is generally termed as a “die set” or simple as the “die”

Press working operations:-

1.Cutting operations:-In cutting operations the work piece is stressed by its ultimate strength.The stresses caused in the metal the applied forces will be shear stresses. The cutting operations include:(a) Blanking (b) Punching (c) Notching (d) Perforating (e) Trimming (f) Shaving

2. Forming operations:-In forming

operations , the stresses are below the

ultimate strength of the metal , in this

operation , there is no cutting of the metal

but only the contour of the work piece is

changed to get the desired product. The

forming operations include.(a) Bending (b) Drawing (c) Squeezing