Sintering
for metals
The use of heat to convert a powder into a solid, without becoming a liquid
- a mould is made of the product which is filled with metal powder
- high pressure is applied to the powder, suing idustrial press
- powder is heated to a temp below melting poing of metal
- individiual particles of metal powder fuse together
higher the pressure and temperature = greater strength of final product
Pros of sintering
Pros:
1. doesn’t need much energy as casting process
2. can create products from different mixture of powders
3. create products with lower density than solid metal
Rapid prototyping
for polymers
The use of addititive manufacture to make a complete part of component in a single operation
Eg: fused deposition modelling (3D printing) and stereolithography (use of laser to make polymer products)
Pros and cons of rapid prototyping
Pros:
* complex parts can be carried out more quickly than several separate parts
* allows rapid evaluation
* unique designs can be made
Cons:
* limited range of materials
Fused deposition modelling
type of rapid prototyping process
- a 3D CAD drawing is created, which has been broken down into a series of layers
- first layer is melted and deposited by printing head, so sits on the base. cools and solidifies when it is deposited
- printing head rises by the thickness of one layer, deposits next layer of polymer, sits on first layer (this step repeats until full thickness has been acheived)
- finished item can be removed from base
this process is used in 3D printing
Sawing
material removal: cutting
- uses movement to progressively cut away material
- each saw tooth cuts a small groove into a material
the harder the material, the smaller the saw teeth
Types of saws
material removal: cutting
Hacksaw: cut metal and polymers
Coping saw: cuts curves shapes. cuts polymers or timber
Tenon saw: timber
Jigsaw: most types of material/thickness
Shearing
material removal: cutting
- applying a force from opposite sides of a metal sheet causing the sheet to separate
Laser cutting
material removal: cutting
- used to cut thin sheets of polymer or metal
- the material along the cut line is vapourised
cylindrical
material removal: turning
- produces a uniform shape of same diameter
- tool moves along the length of the material (reduces diameter)
Taper
material removal: turning
- diameter is larger at one end, and smaller at the other
Boring
Material removal: turning
- use of a single-point tool to produce an internal hole
Face milling
Slot milling
Bending
shaping, forming, manipulation
- physically deforming a material
- forcing something straight into a curve or angle
Folding
shaping, forming, manipulation
- changing the dimentions or shape of a solid maerial, without changing volume
- bending material over itself, so one part cover another
Press forming
shaping, forming, manipulation
used to change the shape of a sheet material using pressure from a press
* place a sheet of material 2 moulds/ram and die.
* the ram and die/moulds fit together with a thin gap between them in the shape required
* a press applies pressure to permanently deform the metal sheet
Punching and stamping
shaping, forming, manipulation
punching: a hole is made, and material pushes out is scrap
shtamping: the shape pushed out is required, and the metal around it is scrap
Sand casting
casting and moulding
a shaping process where a mould, made form sand, is filled with molten metal
* molten metal is poured into the mould through the sprue, and allowed to solidify
* each sand mould is used just once as sand is knocked/shaken off the casting. Sand can be resused to make other moulds
* sprue, riser, runner can be cut off the cast part
Pressure die casting
a shaping process where molten metal is forced into a resuable metal mould
* during casting process, the parts of the die is brought together.
* the pressure forces the liquid metal into the cavity
* once metal has solidified, the die is taken apart and cast part removed
Injection moulding
a shaping process for polymers, where polymer is forced into a reusable metal mould
* polymer granules are loaded into feed hopper
* rotating screw pushes polymer along, melted by heaters
* liquid polymer is compressed by cone shaps. increases pressure, liquid is forced into the mould
* mould is cooled, component ejected
Threaded fastening
products such as screws, nuts, bolts that can be used to make a temporary joint
Rivets
used to hold sheets of material together
* hole is drilled into overlapping sheets of material
* rivet is inserted through hold, ends are hammered to mechanically hold sheets in place
Soldering
a joining process where metal parts are attached together using a filler wire, which melts and runs between them, typically melted using a soldering iron.
