Anglicky v odborných předmětech "Support of teaching technical subjects in English “

1. Anglicky v odborných předmětech"Support ofteachingtechnicalsubjects in English“ Tutorial: Engineering technology Topic: Sinteredmetallicmaterials Prepared by: Ing. Elena Nová Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

2. Sintered metallic materials

3. Sintered metallic materials 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.

4. Sintered metallic materials • 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

5. Sintered metallic materials • 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.

6. Sintered metallic materials • Technological process: • 1. Production of metal’s 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

7. Sintered metallic materials • 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.

8. Sintered metallic materials • 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

9. Sintered metallic materials • Powder pressing • Purpose is to achieve partly compact basic shape of final product before sintering. • Pressures therefore move in a range of 200 to2000 Mpa. • Strait-forward pressing can be • - one sided (pic. a) • - both sided (pic. b) • - from all sides (pic. c)

10. Sintered metallic materials • 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 rod’s shape.

11. Sintered metallic materials • 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.

12. Sintered metallic materials • 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.

13. Answer the questions: • 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?

14. What have these products in common? • Name!

15. Použitá literatura • http://www.ksp.tul.cz/cz/kpt/obsah/vyuka/skripta_tkp/sekce/04.htm