1. Sheet metal processing
Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment

2. FUNDAMENTALS OF METAL FORMING
Overview of Metal Forming
Material Behavior in Metal Forming
Temperature in Metal Forming
Strain Rate Sensitivity
Friction and Lubrication in Metal Forming

3. Metal Forming
Large group of manufacturing processes in which plastic deformation is used to change the shape of metal workpieces
The tool, usually called a die, applies stresses that exceed yield strength of metal
The metal takes a shape determined by the geometry of the die

4. Stresses in Metal Forming
Stresses to plastically deform the metal are usually compressive
Examples: rolling, forging, extrusion
However, some forming processes
Stretch the metal (tensile stresses)
Others bend the metal (tensile and compressive)
Still others apply shear stresses

5. Material Properties in Metal Forming
Desirable material properties:
Low yield strength and high ductility
These properties are affected by temperature:
Ductility increases and yield strength decreases when work temperature is raised
Other factors:
Strain rate and friction

6. Bulk Deformation Processes
Characterized by significant deformations and massive shape changes
"Bulk" refers to workparts with relatively low surface area‑to‑volume ratios
Starting work shapes include cylindrical billets and rectangular bars

7. Basic bulk deformation processes: (a) rolling

8. Basic bulk deformation processes: (b) forging

9. Basic bulk deformation processes: (c) extrusion

10. Basic bulk deformation processes: (d) drawing

11. HOT and COLD WORKING

12. HOT and COLD WORKING
Cold working is metal forming performed at room temperature.
Advantages: better accuracy, better surface finish, high strength and hardness of the part, no
heating is required.
Disadvantages: higher forces and power, limitations to the amount of forming, additional
annealing for some material is required, and some material are not capable of cold working.
Warm working is metal forming at temperatures above the room temperature but bellow the recrystallization one.
Advantages: lower forces and power, more complex part shapes, no annealing is required.
Disadvantages: some investment in furnaces is needed.
Hot working involves deformation of preheated material at temperatures above the re crystallization temperature.
Advantages: big amount of forming is possible, lower forces and power are required, forming
of materials with low ductility, no work hardening and therefore, no additional annealing is required.
Disadvantages: lower accuracy and surface finish, higher production cost, and shorter tool life.

13. Friction in Metal Forming
In most metal forming processes, friction is undesirable:
Metal flow is retarded
Forces and power are increased
Wears tooling faster
Friction and tool wear are more severe in hot working

14. Lubrication in Metal Forming
Metalworking lubricants are applied to tool‑work interface in many forming operations to reduce harmful effects of friction
Benefits:
Reduced sticking, forces, power, tool wear
Better surface finish
Removes heat from the tooling

15. Considerations in Choosing a Lubricant
Type of forming process (rolling, forging, sheet metal drawing, etc.)
Hot working or cold working
Work material
Chemical reactivity with tool and work metals
Ease of application
Cost

16. Definitions Plastic Deformation Processes Bulk Deformation Processes
Operations that induce shape changes on the work piece by plastic deformation under forces applied
by various tools and dies.
Bulk Deformation Processes
These processes involve large amount of plastic deformation. The cross-section of workpiece changes without volume change. The ratio cross-section area/volume is small. For most operations, hot or warm working conditions are preferred although some operations are carried out at room temperature.
Sheet-Forming Processes
In sheet metalworking operations, the cross-section of work piece does not change—the material is only subjected to shape changes. The ratio cross-section area/volume is very high.
Sheet metalworking operations are performed on thin (less than 6 mm) sheets, strips or coils of metal by means of a set of tools called punch and die on machine tools called stamping presses. They are always performed as cold working operations.

17. Bulk Deformation Processes
Rolling: Compressive deformation process in which the thickness of a plate is reduced by squeezing it through two rotating cylindrical rolls. Forging: The workpiece is compressed between two opposing dies so that the die shapes are imparted to the work. Extrusion: The work material is forced to flow through a die opening taking its shape Drawing: The diameter of a wire or bar is reduced by pulling it through a die opening (bar drawing) or a series of die openings (wire drawing)

18. Rolling
Definition Rolling is a Bulk Deformation Process in which the thickness of the work is reduced by compressive forces exerted by two opposing rolls

19. 19

20. Rolling
Important Applications:
Steel Plants,
Raw stock production (sheets, tubes, Rods, etc.)
Screw manufacture

21. Sheets are rolled in multiple stages (why ?)
Rolling Basics
Sheets are rolled in multiple stages (why ?)
Screw manufacture:

22. Forging
Definition
Forging is a Bulk Deformation Process in which the work is compressed between two dies. According to the degree to which the flow of the metal is constrained by the dies there are three types of forging:
ΠOpen-die forging
 Impression-die forging
Ž Flash less forging

23. Forging
Deformation process in which work is compressed between two dies
Oldest of the metal forming operations, dating from about 5000 B C
Components: engine crankshafts, connecting rods, gears, aircraft structural components, jet engine turbine parts
Also, basic metals industries use forging to establish basic form of large parts that are subsequently machined to final shape and size

24. Types of Forging Dies
Open‑die forging - work is compressed between two flat dies, allowing metal to flow laterally with minimum constraint
Impression‑die forging - die contains cavity or impression that is imparted to workpart
Metal flow is constrained so that a flash is created
Flashless forging - workpart is completely constrained in die
No excess flash is created

25. Forging

26. Open‑Die Forging Compression of workpart between two flat dies
Deformation operation reduces height and increases diameter of work
Common names: upsetting or upset forging

27. Open‑Die Forging with No Friction
If no friction occurs between work and die surfaces, then homogeneous deformation occurs

28. Open-Die Forging with Friction
Friction between work and die surfaces constrains lateral flow of work, resulting in barreling effect
In hot open-die forging, effect is even more pronounced due to heat transfer at and near die surfaces, which cools the metal and increases its resistance to deformation

29. Impression‑Die Forging
Flash is formed by metal that flows beyond die cavity into small gap between die plates
Flash serves an important function:
As flash forms, friction resists continued metal flow into gap, constraining material to help fill die cavity
In hot forging, metal flow is further restricted by cooling against die plates

30. Multi-Step Impression‑Die Forging
Several forming steps are often required, with separate die cavities for each step
The function of each individual step can be:
To redistribute metal
To produce desired metallurgical structure due to metal flow
To produce final part geometry

31. Advantages and Limitations
Advantages of impression-die forging compared to machining from solid stock:
Higher production rates
Less waste of metal
Greater strength
Favorable grain orientation in the metal
Limitations:
Not capable of close tolerances
Machining often required to achieve accuracies and features needed

32. Flashless Forging
Starting workpart volume must equal die cavity volume to very close tolerance
Process control more demanding than impression‑die forging
Best suited for geometries that are simple and symmetrical
Process often classified as precision forging

33. Forging Calculations
Just at the yield point assumes the strain, ε = 0.002
The flow stress at any value of strain:
Yf = Kεn
The force required for upset forging:
F = KfYfAf - as strain increases A increases
- use conservation of volume
Where Kf = is the forging shape factor
μ – coefficient of friction (at Die-work interface)
D – workpart diameter (or contact length with die)
h – workpart height
A – cross-sectional area (in contact with die)

34. Quality of forged parts
Surface finish/Dimensional control:
Better than casting (typically)
Stronger/tougher than cast/machined parts of same material
[source:

35. WHAT is EXTRUSION
A material is pushed or drawn through a die of the desired cross-section .Any solid or hollow cross-section may be produced by extrusion, which can create essentially semi-finished parts. The metal can forcing through a die in the same direction or opposite direction.

36. Typical use: ductile metals (Cu, Steel, Al, Mg), Plastics, Rubbers
Extrusion
Typical use: ductile metals (Cu, Steel, Al, Mg), Plastics, Rubbers
Common products:
Al frames of white-boards, doors, windows, …

37. Extrusion: Schematic, Dies
Exercise: how can we get hollow parts?

38. The cross-sections that can be produced vary from solid round, rectangular, to L shapes, T shapes.
Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). Extrusions can be done with the material hot or cold.
Commonly extruded materials include metals, polymers, ceramics, and foodstuffs.

39. Extruded products
Typical products made by extrusion are railings for sliding doors, tubing having carious cross-sections, structural and architectural shapes, and door and windows frames.
                                                                                           Extruded products

40. Drawing
Similar to extrusion, except: pulling force is applied
Commonly used to make wires from round bars

41. WHAT is DRAWING?
Drawing is an operation in which the cross-section of solid rod, wire or tubing is reduced or changed in shape by pulling it through a die.
The principle of this procedure consist of reducing the thickness of a pointed ,tapered wire by drawing it through a conical opening in a tool made of a hard material.The wire will take shape of the hole.

42. Drawing improves strength and hardness when these properties are to be developed by cold work and not by subsequent heat treatment
Where is it used?
This process is widely used for the production of thicker walled seamless tubes and cylinders therefore; shafts, spindles, and small pistons and as the raw material for fasteners such as rivets, bolts, screws.

43. DRAWING TOOLS
The most important tool in the drawing process is without doubt the drawplate.This consist of a plate of high grade steel into which similar shaped holes have been placed whose size in evenly reduced from one hole to another.
The most common drawplate have round holes and are used to reduce the size of round wire.
Drawing wire with the draw tongs
drawbench

44. How such a drawplate hole is made