1. Engineering Materials and Processes Lecture 7 – Mechanical shaping of metals
Prescribed Text:
Ref 1: Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN:
Readings:
Callister: Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN
Ashby 1: Ashby, M. & Jones, D., 2011, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Ashby 2: Ashby, M. & Jones, D., 2011, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Lecture (2 hrs):
Ref 1, Ch 1: Engineering materials;
Ref 1 Ch 2: Properties of materials.
Laboratory 1 (2 hrs): Hardness test
Callister: Ch 1, 2, 18-21
Ashby 1: Ch 1, 2
Ashby 2: Ch 1 1

2. Mechanical Deformation of Metals
Reference Text
Section
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann
Ch 7
Additional Readings
Section
Sheedy, P. A, Materials : Their properties, testing and selection
Ch 13
Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Ed, Wiley, New York.
N.A.
Ashby, M.F., Materials Selection in Mechanical Design, 4th Ed, Butterworth Heinemann, Oxford, UK.
Engineering Materials and Processes

3. Engineering Materials and Processes
Ashby: Fig 13.2
The classes of processes
Engineering Materials and Processes

4. Hot-working processes (Higgins 7.2)
Hot Working processes are carried out above the recrystallisation temperature of the material.
7.2 Hot Working Processes
7.2.1 Forging
7.2.2 Hot-rolling
Engineering Materials and Processes

5. Hot-working processes: Forging (Higgins 7.2.1)
VIDEO:
Open-die forging can produce forgings from a kg to more than 150 tonnes.
“Open-die” means the metal is not confined laterally during forging.
The process works progressively from the starting stock into the desired shape. Flat-faced dies are usual.
Wide range of shapes and sizes are possible, especially suited to large custom parts like a ship’s propeller shaft.
Seamless Rolled Ring Forging: Starts with a cast billet, then upset and punched to form a donut shape, then rolling and squeezing (or in some cases, pounding) the donut into a thin ring. Ring diameters can be anywhere from a 100mm to 10m.
Engineering Materials and Processes

6. Hot-working processes: Hot-Rolling (Higgins 7.2.2)
Hot Rolling (Billet to plate/sheet):
Dalarna University
(Creative Commons)
Breaking down billets (large thick slabs cast from the furnace) into successively thinner plate, and finally sheet.
Fun and Games with Hot Rolling…
“Cobble” = British terminology
“Miss-roll = US terminology
HD-720
Cobble:
Cobble 2:
Engineering Materials and Processes

7. Hot-working processes: Extrusion (Higgins 7.2.3)
Like squeezing toothpaste from a tube, material is forced through a die and is plastically deformed into the cross-section of the die.
The die hole can be almost any shape, (e.g. a circular die will make a rod)
Mostly used for low temperature metals: copper pipes, aluminium extrusions.
Steel can only be drawn or hot rolled, but not extruded in the same way as aluminium.
Pity. Would have been a nice way to make steel pipe.
openlearn.open.ac.uk
Engineering Materials and Processes

8. Hot-working processes: Extrusion (Higgins 7.2.3)
Extruding a hollow shape is an obvious problem. How do you hold the die that forms the hole?
Extrusion bridge die making a hollow section product.
Note: in reality, the die and ring are held together.
Engineering Materials and Processes

9. Hot-working processes: Extrusion (Higgins 7.2.3)
Aluminium dominates the extrusion industry because the metal has excellent ductility without the need for extreme temperatures. It is also an obvious choice for window frames, structural and decorative parts, and almost anything of a constant cross-section.
Heated to about 900oF (480oC) to keep it well above the recrystallisation temperature (150oC).
The design of the extrusion profile effects extrusion performance. (E.g. Better to have symmetry, avoid long flats, minimize internal holes, etc…)
PBCLinear
Engineering Materials and Processes

10. Hot-working processes 3 (Higgins 7.2)
Other Hot Working Processes
Hot forming of Coil Springs:
Friction Welding:
Engineering Materials and Processes

11. Cold-working processes (Higgins 7.3)
Cold Working processes are carried out below the recrystallisation temperature of the material.
See text:
7.3 Cold Working Processes
7.3.1 Cold-rolling
7.3.2 Drawing
7.3.3 Cold-pressing and deep-drawing
Bolts:
7.3.4 Spinning
7.3.5 Stretch-forming
7.3.6 Coining and embossing
7.3.7 Impact-extrusion
Engineering Materials and Processes

12. Cold-working processes: Cold Rolling (Higgins 7.3.1)
Cold Rolling Steel Sheet:
Steelmaking: Cold Rolling
by CorusBCSATraining
Roll Curving Steel plate for Wind Turbine Tower
Engineering Materials and Processes

13. Cold-working processes: Drawing (Higgins 7.3.2)
Cold Drawing of Hexagonal Bar
Engineering Materials and Processes

14. Cold-working processes:
Cold Pressing and Deep Drawing (Higgins 7.3.3)
Forming Bolts
Engineering Materials and Processes

15. Cold-working processes:
Spinning (Higgins 7.3.4)
Metal Spinning
Engineering Materials and Processes

16. Cold-working processes:
Stretch-forming (Higgins 7.3.5)
Stretch Forming
Engineering Materials and Processes

17. Cold-working processes:
Coining and embossing (Higgins 7.3.6)
Stamping
Engineering Materials and Processes

18. Cold-working processes:
Impact Extrusion (Higgins 7.3.7)
Impact Extrusion
Engineering Materials and Processes

19. Cold-working processes:
Roll Forming
Roll Forming – Roofing
Spiral Ducting
ERW Pipe Forming (5” or 125mm)
Engineering Materials and Processes

20. Powder Metallurgy (Higgins 7.4)
Powder Metallurgy (PM) involves pressing the powder and then heating (above recrystallisation but below the melting point) – called sintering – which binds the particles together.
See text:
7.4.1 Uses of powder-metallurgy
7.4.2 Cemented carbides
7.4.3 Sintered-bronze bearings
Powder Metallurgy
Engineering Materials and Processes

21. Machining metals (Higgins 7.5)
Machining is a cold-working process in which the cutting edge of a tool forms shavings or chips of the material being cut.
See text: Higgins 7.5
Machining Centre: 5 axis various jobs
High Speed Video: Milling Cutter
Machining a large shaft – Lathe
Engineering Materials and Processes

22. Profile Cutting This is for cutting sheet material. Usually CNC
Laser. Fast, accurate, good finish, many materials. Finest kerf. Fussy maintenance.
Water jet: Almost any material. No heat damage.
High speed laser cutting
Water jet cutting bullet-proof glass
Engineering Materials and Processes

23. Profile Cutting This is for cutting sheet material. Usually CNC
Flame Cut (Gas): Cheaper system, good for thick steel plate. Worst quality.
Plasma: Better finish than flame cut, but cheaper than laser.
CNC router: Typically wood, plastic and soft metals (e.g. thin aluminium), often held down by vacuum onto a spoil board (MDF)
High speed laser cutting
CNC Plasma
Engineering Materials and Processes

24. Video Forming & Shaping Metal
Davis, John. Warriewood, NSW : Classroom Video, c2002. DVD (22 min.)
Hot Forming, Cold Forming, Machining
Mt Druitt College Library: DVD 671.3/FORM
Recommended Viewing: All sections.
Engineering Materials and Processes 24

25. Online Properties Resources.
Graphical comparison of materials properties.
DoITPoMS: Dissemination of IT for the Promotion of Materials Science
Wikipedia: Materials properties
Forming: Forging, Rolling, Extrusion, Machining
CorusBCSATraining
Engineering Materials and Processes 25

26. Engineering Materials and Processes
GLOSSARY
Hot forming
Cold forming
Recrystallisation
Annealing
Work Hardening
Stress Relieving
Drawing
ERW
CNC
Profile Cutting
Plasma Cutting
Laser Cutting
Oxy Cutting
Water Jet Cutting
Open Die Forging
Upset Forging
Cavity Forging
Coolant
Facing
Turning
Metal Spinning
Roll Forming
Extrusion
Hot Rolling
Cold Rolling
Powder Metallurgy
Sintering
Drawing
Blanking
Bending
Stretching
Engineering Materials and Processes 26

27. Define all the glossary terms.
QUESTIONS
Callister: NA
Moodle XML: Processing
Define all the glossary terms.
Explain which type of process would be used for making railway tracks and compare it to the process of making road crash barriers. Explain the difference.
Why are aluminium and copper based metals extruded, but not steel.
Explain the process of making an ERW round pipe.
Make a table comparing the various profile cutting technologies. Compare machine cost, running cost, speed, accuracy, thickness, material range.
CNC if far superior to manual control of a machining operation. Why do we still have manual machines at all?
A metal gear needs to be manufactured in the tens of thousands. Compare the process options of powder metallurgy, machining, casting and forging. Include cost of die, material costs, running costs, speed, accuracy, product performance. (See:
Engineering Materials and Processes 27