Joining Techniques Snap rivets, countersunk head rivets and pop rivets. 0.0 / 5 ? Design & Technology: Resistant MaterialsRivetsASEdexcel Created by: Milly EarleCreated on: 03-05-14 19:09 Rivets Snap Rivets Round heads Strong joint You have to have access to both sides of the material Pop Rivets Can be applied from one side of the material Not very strong Countersunk Head Rivets Important when the surface of the material has to be flat 1 of 6 Welding 1 Welding Two pieces of metal are melted together- as strong as the parent metal Oxyacetylene- oxygen and acetylene are used as the heat source and a filler rod of the same metal is used to complete the joint Metal Inert Gas (MIG)- the filler rod supplied a current to the arc whilst it is protected from oxidation by an inert gas, sometimes argon. Safety issues Brazing Joining two mild steels with spelter, (an alloy of copper and zinc) The joint area should be cleaned with an emery cloth Flux should be applied to the joint to prevent oxidation and to allows the spelter to flow Little training needed to untake Care should be taken to ensure oxidation doesn't happen to create a weak joint 2 of 6 Welding 2 Hard Soldering Similar to brazing but at a lower temperature Low temperatures required Different melting points to enable complex decorative pieces to be produced Weak joints that don't withstand stress 3 of 6 Chemical Joints Tensol Cement Used to join thermoplastics Tensol cement is a solvent and melts the thermoplastics when applied The materials should be clamped for 24 hours It is a permanent joint Gives off strong fumes It can cause damage to the surface of the acrylic Polystyrene Cement Same as Tensol Cement but for polystyrene rather than acrylic 4 of 6 Adhesives PVA Wood glue Water soluble Needs 24 hours to set and needs clamps to hold it together The wood needs to be clean and it needs to have no gaps It will stain wood Very strong Epoxy-resin Thermosetting plastic that goes hard when mixed with a hardener It is an irreversable reaction Takes a few hours to set Produces a very strong bond, is waterproof and is chemical and heat resistant 5 of 6 Adhesives 2 Contact Adhesives Useful when glueing laminates Instant sticking Gives off toxic fumes Can't be adjusted once stuck Hot Melt Glue It is a thermoplastic Useful for small model tasks Quick to harden and bond Glue gun can be very hot and the glue can cause blistering if on skin 6 of 6
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