Tutorial: Engineering technology Topic: Sintered metallic
materials Prepared by: Ing. Elena Nov Projekt Anglicky v odbornch
pedmtech, CZ.1.07/1.3.09/04.0002 je spolufinancovn Evropskm socilnm
fondem a sttnm rozpotem esk republiky.
Slide 3
Sintered metallic materials
Slide 4
Sintered materials Are produced from metallic powders steel /
copper / tin / aluminum, which are pressed under great power into
required shapes and in next process sintering are bonded into a new
material with very high strength.
Slide 5
Advantages of powder metallurgy: Possibility to create
complicated shapes (geared wheels, shapes, parts of absorbers etc.)
Possibility to make self greasing / benefit of porosity / sliding
gears Dimensional accuracy gain by precision tools for pressing and
calibration Complete usage of entry material (without waste) High
efectivity in manufacturing of large series
Slide 6
Disadvantages of sintering technology Great press force is
required Press moulds are expensive Size of products is limited due
to pressing force and smaller net densening inside large products
Shape difficult parts with transversal holes or threads are not
possible to press out.
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Technological process: 1. Production of metals powder 2. Mixing
of press mixtures to achieve required chemical-physical properties
of final product 3. Pressing pressed powder has geometrical shape
of the final product 4. Sintering is made in an Oven with
protective atmosphere at max. temp. 1140 deg. 5. Final operation
depends on product applicability: - calibration - conservation -
saturation - honing - machining
Slide 8
Powder manufacturing Powders are produced as follows - Physical
milling and crushing, is used mainly for Cu, Fe, Al, Cr, Mn -
atomization of liquid metal by air or water mainly for Pb, Zn, Sn,
Al, Fe - steam condensation used mainly for Zn, Cd - chemically
based on ore reduction is used with Cu, Ag, Fe, Ni, Co, W, Mo,
Ti.
Slide 9
Powders treatment Mostly by - powder reduction after their
manufacture by spraying air - powder drying off after their
manufacture by spraying of water - screening and classification of
powder according to size of particles - addition of other parts in
accordance with production special requirements - grease addition
to improve pressing
Slide 10
Powder pressing Purpose is to achieve partly compact basic
shape of final product before sintering. Pressures therefore move
in a range of 200 to 2000 Mpa. Strait-forward pressing can be - one
sided (pic. a) - both sided (pic. b) - from all sides (pic. c)
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At rolling - powder from holder entry between rolls, which
press and compact it. Product are rods or strips At extrusion
through calibrated opening produce semi-products of rods
shape.
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Powder Sintering Sintering we understand a heat influencing on
semi-product made in previous operation compacting. Sintering
temperature depends on composition of coupled material. In a case
of semi-product sintering made from a single material, the chosen
temperature is about 80% of its melting temperature. Joining of
powder particles is by diffusion.
Slide 13
Sintering Due to danger of oxidation is sintering made in
protective atmosphere. Calibration Sintered products have
satisfactory dimensional accuracy and surface quality. At a very
high accuracy requirements a high precision calibration form is
used.
Slide 14
What is a sintering? What steps are used for manufacturing of
sintered products? How accurate are sintered products? Advantages
of sintering materials? Disadvantages of sintering materials?