1. MANUFACTURING
(Lecture 2)

2. Manufacturing Processes
Processes add value to materials
A process involves a number of steps or operations
Four basic processes applied on production materials are forming, material removal, assembly (or joining) and conditioning
Forming operations change the geometry of the starting material without cutting it
Material removal or separating processes remove a part of the starting material using a tool to get the desired geometry
Combining processes join two materials or deposit material onto the exterior surface of the starting material
Conditioning processes add value to the starting material by improving its internal and physical properties

3. Forming Processes Casting
A material in a liquid or semisolid form is poured or forced to flow into a mold cavity and allowed to solidify, thus taking the solid shape of the cavity
The process can be applied on metals, ceramics and plastics
The term casting is commonly used for metals
The term molding is used for plastics
Examples of molds – cake-pan, an ice-cube-tray or the footprints on a beach
Types of castings – sand casting and die casting
Sand casting – pouring molten metal into a sand mold, breaking up the mold to remove the casting
Sand casting requires a pattern – a full sized model of the part
Die casting is a permanent-mold-casting – molten metal is injected into the mold cavity under high pressure
Molds for die casting are named as dies

4. Forming Processes Pressing
Casting with a two-piece mold
Pressing
Pressing is commonly used for majority of sheet metal parts of an automobile
A measured amount of material is poured into a mold. A plunger with its own shape is lowered to force the material to spread out and fill the mold
The material is forced into the shape of the mold at the bottom and the shape of the plunger at the top
Mechanical or hydraulic presses are used
The plunger and the base of a forming die transform the sheet metal into the required shape – drawing – fuel tank of a motorbike

5. Forming Processes Pressing
Rolling is a type of pressing – thickness of the starting material is reduced by compressive forces exerted by two opposing rolls
Great pressure can make the powdered metal into a solid. The material is then heated to make the object hard – sintering
Some parts of an automobile that are made through pressing
Fenders
Bumpers
Trunk Lids
Doors
Hoods
Rolling of a slab

6. Forming Processes Forging The oldest metal forming operation
Work part is heated and compressed using either impact or gradual pressure part
Forging machine applying an impact load – forging hammer
Forging machine applying gradual pressure – forging press
Examples – high-strength components for automotive and aircrafts like engine crank shafts and connecting rods, gears, aircraft structural components, and jet engine turbine parts

7. Extruding a red hot metal
Forming Processes
Extrusion
A compression process in which the work metal is forced to flow through a die opening, thereby taking the shape of the opening as its own cross-section
Toothpaste is a very good example of the process
Different shapes are possible especially with hot extrusion
The end product does not require much more shaping and machining
Extruding a red hot metal

8. Forming Processes Blow Molding
Air pressure is used to inflate soft plastic into a mold cavity
One-piece hollow plastic parts with thin walls are possible, such as bottles and similar containers
The technology is borrowed from the glass industry with which plastics compete in the disposable or recyclable bottle market

9. Material Removal Processes
Operations that remove excess material from the starting workpiece to get the desired geometry
Use of knives and scissors is a common example
Important processes – shearing, sawing and machining operations such as turning, drilling and milling, shaping and planing and grinding
Nontraditional processes – lasers, filters, magnets and electrochemical energy
Sawing
A narrow slit is cut into the workpiece by a tool consisting of a series of narrowly spaced teeth
Most sawing operations – work is held stationary and saw blade is moved relative to it
Types – hacksawing and bandsawing
Hacksaw blade – thin straight tool with cutting teeth on one edge
Bandsaw blade – endless flexible loop with teeth on one edge – pulley-like drive mechanism

10. Material Removal Processes
Sawing
A power hacksaw
A vertical bandsaw

11. Material Removal Processes
Shearing
Metal cutting operation along a straight line between two cutting edges – similar to using a pair of scissors
Typically used to cut large sheets into smaller sections for subsequent pressworking operations
Other similar processes are blanking and punching
Shearing
Blanking and punching

12. Material Removal Processes
Turning
Cutting tool with a single cutting edge – rotating workpiece to generate a cylindrical shape
Turning is commonly performed using a lathe
Drilling
Used to create a round hole
A rotating tool that has two cutting edges
The holes can be made from 1/10,000 of an inch to 3½ inches
Milling
Rotating tool with multiple cutting edges – plane or straight surface
Types – vertical milling and horizontal or face milling

13. Material Removal Processes
Shaping and Planing
Single-point cutting tool moved linearly relative to the workpiece
Creating a straight, flat surface
Shaping – tool provides the speed motion and the workpiece remains static
Planing – workpiece provides the speed motion while the tool remains motionless.
Grinding
Used to provide surface finish and the uniform thickness of the workpiece
Abrasive particles are used – sand paper or grinding wheel
Abrasives – very small crushed particles of hard materials like aluminum oxide and silicon carbide
Grinding wheel – usually disk-shaped, precisely balanced for high rotational speeds
Common forms of grinding – polishing, buffing and the use of toothpaste
Grinding tools

14. Assembly Processes
Two or more separate parts are joined to form a new entity
Components are connected – permanently or semi permanently
Types – mechanical methods, thermal methods and adhesive bonding
Mechanical Assembly
Various fastening methods – use of hardware components, called fasteners
Products using mechanical assembly – automobiles, large and small appliances, telephones, furniture, utensils and wearing apparels
Categories – nails, threaded fasteners and rivets
Mechanical assembly is often preferred for its ease of assembly and disassembly
Nails are commonly used for wood – finishing nails, box nails and common nails