metal joining processes

Question 1

MIG welding

Answer 1

• electrode wire and inert gas (CO2 or argon) used
• for thin gauge metals, medium carbon steel and aluminium
• one off or on an assembly line
• climbing frames
• bike frames
• vehicle exhausts

Question 2

TIG welding

Answer 2

• uses filler rod
• accurate and strong welds
• requires high skill
• slow
• uses inert gas (argon or helium)
• stainless steel ladders for boats or swimming pools
• welding stainless steel car exhausts

Question 3

oxy-acetylene welding

Answer 3

• uses steel filler rod
• useful for quick repairs
• good for remote locations where there is no electric power supply
• used to weld mild steel sheet/tube/plate where arc welding processes are not available

Question 4

spot welding

Answer 4

• sheet held between two copper electrodes that form a weld when the charged electrodes make contact with metal
• used to weld mild steel sheet metal at points along a length

Question 5

soldering

Answer 5

• uses filler material of lower melting point than the metal being joined
• typically an alloy of tin and copper
• lightweight applications
• joining precious metals
• for jewellery
• joining copper pipes in plumbing

Question 6

brazing

Answer 6

• brass filler rod
• uses oxy-acetylene or a gas and compressed air brazing hearth
• one off or small batch production
• used to join dissimilar metals
• lower temperature than welding so suitable for joining thinner gauge metals

Question 7

riveting and pop riveting

Answer 7

• riveting uses two pieces that are overlapped and drilled with the end of the shaft then hammered over to join
• pop riveting uses a rivet gun and rivet to join, is good for where the underside of a joint is inaccessible
• sheet metal or plate joining

Question 8

temporary fasteners and joining methods

Answer 8

• used where a permanent joining method is not required
• used in situations where a product may need to be disassembled or accessed for repair

Question 9

self tapping screws

Answer 9

• for joining thin sheet metal
• pilot hole drilled through, and as the screw is screwed in it cuts its own thread which holds the screw in place

Question 10

machine screws

Answer 10

• the thread is the whole length of the shaft
• to join thicker pieces of metal
• top part has a clearance hole bigger than the thread on the bolt
• bolt goes through this and screwed into a threaded hold in second piece

Question 11

nuts and bolts

Answer 11

• similar to machine screws
• go all the way through both pieces of metal
• nut is tightened onto the end to keep the pieces together