Joining Techniques

Question 1

Adhesives (plastics)

Answer 1

PVA
Tensol cement
Liquid polycement
Contact adhesive
Epoxy resin

Question 2

PVA

Answer 2

• very effective on wood if both surfaces of the joint are edge grain.
• a properly glued joint can be as strong as a single piece of wood.
• won’t work on end grain surfaces.

Question 3

Tensol cement

Answer 3

• joins plastics (eg acrylic) together permanently.
• glue applied to both surfaces.
• clamped for 24hrs to give a permanent joint.
• cant clean excess off, leaves strings,

Question 4

liquid polycement

Answer 4

• more appropriate for plastic.
• works by capillary action.
• cleaner and easier to use.
• water like consistency.

Question 5

contact adhesive

Answer 5

• can be used to join plastics.
• adhesive is applied to both surfaces and when appears to be dry is pushed together.
• used for large surface areas.

Question 6

epoxy resin

Answer 6

• many adhesives are plastics themselves.
• Araldite is an epoxy resin that hardens when a second chemical is added (catalyst).
• can bond most materials including some plastics.
• messy and smelly
• mix two parts for 1 minute.

Question 7

wood joints

Answer 7

can be designed to hold without the use of glue or fasteners.

Question 8

types of wood joints

Answer 8

half mitre
mortise and tenon
dove tail
lap joint
bridal joint
rebate
finger joint
dowel joint

Question 9

compare a mortise and tenon to a dowel joint

Answer 9

compared to a mortise and tenon, a dowel joint is a poor joint. Much of the surface of the dowel joint is end grain, to which glue adheres to poorly. In a mortise and tenon joint most of the surface of the joint is longitudinal grain.

Question 10

mechanical joining

Answer 10

• temporary/semi permanent
• various mechanical fasteners used
• nails/ screws
• nuts and bolts
• pop rivets

Question 11

thermal joining

Answer 11

heat is used to cause a joint in a variety of ways: soldering, braising, welding

Question 12

soldering

Answer 12

• a process in which two or more metal items are joined together by melting and flowing a filler metal into a joint.
• filler metal has a relatively low melting point.
• in a soldering process heat is applied to the parts being joined, causing the solder to melt and be drawn into the joint by capillary action.
• soft soldering, hard soldering, silver soldering

Question 13

brazing

Answer 13

• a filler metal or alloy is heated to melting temp.
• quick, doesn’t need to much heat.
• widely used in the tool industry to fasten hard metal tips to tools such as saw blades.

Question 14

MIG welding

Answer 14

• metal inert gas
• a form of arc welding
• used for general welding, mild steel
• as well as welding it can be used for cutting plate metal.

Question 15

TIG welding

Answer 15

• tungsten inert gas
• a form of arc welding
• used for welding specialist materials such as aluminium and stainless steel.
• has a filler rod instead of a consumable wire.

Question 16

arc welding safety

Answer 16

tinted visor must be warn to prevent arc eye

Question 17

oxy-acetylene welding

Answer 17

• combination of two gases: oxygen and acetylene.
• v valley produced by grinding on joining materials.
• filler rod used to join similar thickness materials.
• MIG welding cleaner and quicker.