chapter 6 methods of processing materials

Question 1

shaping by wasting definition

Answer 1

cutting away material to leave the desired shape, wasting material, can be done using any tool or machine

Question 2

fabrication definition

Answer 2

involves joining separate materials can be done by cutting joints, using screws, adhesives, heat treatment processes soldering, brazing, welding

Question 2

rolling definition

Answer 2

fabricating process in which metal is passed through rolls

Question 2

4 types of rolling

Answer 2

flat, profile, hot, cold

Question 3

flat rolling definition

Answer 3

the final shape is classed as a sheet (typically less than 3mm) or a plate (typically more than 3mm)

Question 4

profile rolling definition

Answer 4

will give a round rod or other shaped bar such as a structural section (beam, channel, joist)

Question 5

hot and cold rolling definition

Answer 5

if the temperature of the metal is above its recrystallization temperature its hot rolling and vice versa for cold rolling

Question 6

blanking definition

Answer 6

shearing process where a punch and die are used to create a blank from sheet metal or a plate. the process is usually the same as piercing but the piece being punched out is scrap

Question 7

press forming definition

Answer 7

high forces used to squeeze a measured quantity of polymer into shape between heated moulds, produces electrical fittings eg plugs and sockets, handles and bottle tops

Question 8

forging definition

Answer 8

term used for shaping metal by using localized compressive forces. cold forging is one at room temperature. hot forging is done at a high temperature which makes metal easier to shape and less likely to fracture

Question 9

injection moulding definition

Answer 9

molten plastic is forced into a mould using screw powered by a hydraulic rams. materials used are polystyrene, nylon and abs

Question 10

blow moulding definition

Answer 10

mass of material converted into a tube using a mandrel, air is blown into a mould where it takes shape some materials used are pvc and polythene. used to make bottles

Question 11

rotational moulding definition

Answer 11

powdered or liquid polymer is poured into a metal mould which is moved into the heat source and rotated. used for bins, road cones and rowing boats

Question 12

vacuum forging definition

Answer 12

thermoplastic sheet heated until soft, mould is the brought in contact with sheet, vacuum sucks sheet around mould. acrylic pvc and polystyrene can be used. makes egg boxes and seed trays

Question 13

sand casting definition

Answer 13

molten metal is poured into a mould made from sand, most commonly used for single use moulds. used for engine blocks cylinder heads, bases for heavy machinery and man hole covers

Question 14

pressure die casting definition

Answer 14

molten metal is forced into cavity between dies under pressure. used to make small metal toys like toy cars, door handles and taps

Question 15

extrusion moulding definition

Answer 15

screw forces heated plastic through a die, the cools and is cut into lengths. pvc, nylon and abs is used. produces drain pipes and curtain rails