1. Manufacturing Processes
Powders metallurgy(분말금속)
Ceramics(세라믹)
Glasses(유리)
Associate Professor Su-Jin Kim
School of Mechanical Engineering
Gyeongsang National University 1

2. Contents Powder Metallurgy(분말야금) Ceramic Glass Plate, Tubing
Powder production
Blending or mixing
Compaction
Sintering
Ceramic
Mixing particles with additives
Shaping
Drying & Firing
Glass
Plate, Tubing
Blowing, Pressing

3. Powder Metallurgy Usage
PM1:

4. Powder Metallurgy Powder production Blending or mixing(혼합)
Compaction(압축)
Sintering(소결)
Finishing operations(마무리가공)
PM2:

5. Powder Production Atomization (입자화)
Liquid-metal stream is broken into powder by water jet.
Reduction (환원)
Metallic oxides are reduced to the metallic state.

6. Particle size and shape
Particle size is measured and controlled by screening.
Particle shape is expressed by aspect ratio or shape factor.
Size and shape of particles affect the processing characteristics of the powder.

7. Blending metal powders (혼합)
Blending (mixing) powders is the second step, and the purposes are:
to impart physical and mechanical properties and characteristics to the P/M part
obtain uniformity from part to part
lubricants are mixed to improve flow characteristics
binders are used for sufficient green strength

8. Compaction(압축) of metal powders
Powders are pressed into shapes using dies and presses.
Obtain the required shape, density and particle-to-particle contact.

9. Compaction of metal powders
The density after compaction depends on:
compaction pressure
powder composition
hardness of the powder
Higher the density, higher the strength and elastic modulus of the part.

10. Sintering
Sintering (소결) is where compacted metal powder is heated to below its melting point for the bonding of the individual metal particles.
Sintered density increases with temperature and time.

11. Metal Injection Molding (MIM)
Mixing: metal + polymer
Injection monding
Debinding
Sintering
Ceramic Injection Molding (CIM)
Mixing: ceramic + polymer …
MIM:

12. Design for Powder Metallurgy
Simple & uniform shape
Easy ejection from die
Large tolerance reduce cost
Avoid sharp radius

13. Economics of Powder Metallurgy
The cost depends on method of powder production, its quality and quantity purchased.
Due to high cost of punches, dies and equipment for P/M processing, production volume must be high.

14. Ceramic usage
Memory
Pottery
Aerospace
Medical

15. Ceramic usage
Art
Electric resistance
High temperature
Wear resistance

16. Ceramics Ceramics are compounds of metallic and non-metallic elements.
Bonding between atoms can be covalent and ionic.
Various types of ceramics are:
Oxide ceramics O: Alumina Al2O3, Zirconia ZrO2
Carbides C: Tungstem carbides WC, Silicon carbide SiC
Nitrides N: Cubic boron nitride cBN, Titanium nitride TiN, Sialon, Cermets
Silica SiO2
Nanophase ceramic

17. General properties of ceramics
Ceramics are brittle, have high compressive strength and hardness at elevated temperatures, high elastic modulus, low toughness, low density, low thermal expansion, and low thermal and electrical conductivity.
1. Mechanical properties
Sensitivity to cracks, impurities and porosity
Strength in tension is lower than compressive strength.
2. Physical properties
Low specific gravity and have high melting temperatures.

18. Ceramic process Crushing raw materials into very fine particles
Mixing particles with additives
Shaping (성형)
Drying (건조)
Baking in fire (굽기)
Finishing (마무리)
Knife:
Toilet:

19. Clay Forming (성형) • Milling and screening: desired particle size
• Mixing particles & water: produces a "slip"
• Form a "green" component
ram
billet
container
force
die holder
die A o d
extrusion
- Hydroplastic forming:
extrude the slip (e.g., into a pipe)
solid component
- Slip casting:
hollow component
pour slip
into mold
drain
mold
“green
ceramic”
absorb water
• Dry and fire the component

20. Drying (건조) wet slip partially dry “green” ceramic
• Drying: layer size and spacing decrease.
wet slip
partially dry
“green” ceramic
Drying too fast causes sample to warp or crack due to non-uniform shrinkage

21. Firing (굽기) --T raised to (900-1400°C)
--vitrification: liquid glass forms from clay and flows between
SiO2 particles. Flux melts at lower T.
Si02 particle
(quartz)
micrograph of
glass formed
porcelain
around
the particle
70 mm

22. Cementation (시멘트) - mix clay and lime bearing materials
• Produced in extremely large quantities.
• Portland cement:
- mix clay and lime bearing materials
- calcinate (heat to 1400°C)
- primary constituents:
tri-calcium silicate
di-calcium silicate
• Adding water
- produces a paste which hardens
- hardening occurs due to hydration (chemical reactions
with the water).
• Forming: done usually minutes after hydration begins.

23. Glass Glass is an amorphous solid with the structure of a liquid.
All glasses contain at least 50% silica SiO2.
They are resistant to chemical attacks and ranked by their resistance to acid, alkali or water corrosion.

24. Mechanical properties
Consider to be linearly elastic and brittle.
Bulk formed glass has low strength(<40 MPa) due to microcracks on the surface, but the strength of glass fiber is about 2 GPa stronger than steel.
Low thermal conductivity and high electric resistance.
Thermal expansion coefficient is lower than metals and plastics.
Optical properties can be modified by varying their composition and treatment.

25. Glass Forning wind up • Pressing:
plates, dishes, cheap glasses - mold is steel with graphite lining
Gob
Parison
mold
Pressing
operation
• Blowing:
suspended
Parison
Finishing
mold
Compressed
air
• Fiber drawing:
wind up

26. Float method
Molten glass from the furnace is fed into a bath of molten tin.
The glass floats on the tin bath an then moves over rollers and is cut to glass plates.
Plate glass:

27. Glass tubing
Air is blown through the mandrel to make the tube

28. Glass Blowing Glass bottle is made by blowing

29. Glass Pressing Glass vessel is made by pressing.
Block: