Manufacturing Process

Chapter 1

Manufacturing - def - to convert raw material into useful articles with the help of labour or machining.


Chapter 2

Metal casting

Def- of casting- the flow of molten metal into the mould where it solidifies the shape of the mold cavity

Advantage
- Complex shape
- Net shape ability
- very large part
- Variety of metal
- Mass production

Disadvantage
- Poor accuracy
- Poor surface
- Internal defects
- mechanical properties
- environmental impact

Casting technology

Sand casting

Fluilidity
The measure of the capability of a molten metal to flow into the mold cavity before freezing.

Factors effecting fluilidity
1. Pouring temperature
2. Heat transfer
3. Viscosity
4. Metal composition

Riser design

Solidification of metal ( graph)
Solidification of the volume shrinkage (graph)

Shrinkage

Sand casting benefits
1. Cheap casting process
2. Can go up to several tons
3. Cheap machining shapes from bar stock
4. Can be used with most pourable metal and alloy
5. Can intricate shape


The sand casting process

The sand
1. FLOWABILITY
2. PLASTIC DEFORMATION
3. GREEN STRENGTH
4. PERMABILITY


Metal casting
- Shell moulding
- Investment casting process
- Die casting

Molten metal is injected into a closed metal die under high pressure
Pressure maintained during solidification
Die separated and casting ejected
- cold chamber
- hot chamber

Hot chamber

Advantage
- No transfer of molten metal
- Offer fast cycling time
- Good strength product
- Excellent dimensional

Disadvantage
- expensive
- requires high production rates to justify the usage
- cannot be used for high melting point metals


Cold chamber
Advantage
- Good advantage
- Excellent dimensional
- Excellent surface

Disadvantage
- Expensive
- requires high production rates to justify the usage
- The need to transport molten metals

Centrifugal casting
Utilize inertial force by rotation to distribute molten metal into mold cavities.

Process :
Pour molten metal into rotating mould
Metal is held against the mould wall by centrifugal force until it is solidifies

3 types of centrifugal casting
1. True centrifugal casting
2. Semi centrifugal casting
3. Centrifuging

Continuous casting

Fundamental of Metal Cutting

- Plastic deformation in cutting
- Type's of cutting
- Orthogonal cutting => the cutting edge is straight and is set in a position perpendicular to the direction of the primary motion.
- Oblique cutting => the cutting edge is set as an angle, the tool of the cutting edge is inclined , λs.

- Cutting condition
cutting velocity, v
Depth of cut, d
Feed,f

- Chip formation
3 types of chip produced in casting.
1. Discontinuous chip
2. Continuous chip
3. Continuous chip with BUE (build up edge)