Joining

Nuts & Bolts - are used to join a wide range of materials. Bolts and screws are made with a wide range of heads to be turned with a spanner or a screw driver. The head can be countersunk so that it finishes flush with the surface or it can have a head which is proud of the surface - cheese head, pan head dome head, hex head, allen key head. Machine screws have the thread all the way up.

Adhesive Bonding is a modern joining process in which a liquid substance is put on two pieces that you want to join together to provide a long lasting bond. This process is highly useful in bonding two very different materials that can not be welded. Materials that can be bonded together are virtually unlimited. Adhesives come in many forms and can be made from various natural and/or artificial compounds. A problem with this process is the adhesive bonds are not immediate such as welding or nailing. Adhesive bonds take more time to process, in order to allow the adhesives to cure.

Rivets are used to join plates together and they have been used for hundreds of years. Before the use of welding, rivets were used in heavy industries such as ship building. The steel plates used to build ships such as the Titanic and the naval Ships of World War One were held together by steel rivets. Rivets have largely being replaced by techniques such as welding and brazing. However, joining plates together with rivets is still a useful technique especially if the plates to be joined are quite small. Cold rivets are still used in school workshops although the modern pop-riveting technique is more popular. There are snap head rivets which have a circular head, pan head rivets which have a relatively square gead, mushroom rivets which are shaped like a mushroom and countersuck rivets which get wider at the top and have a square top.

Pop riveting is a technique that is used to join thin pieces of metal and it can also be used to join plastic sheet. The rivet has two parts; the pin and the rivet. The pop rivet pliers are used to pull the pin through the rivet and as this happens the rivet is deformed slightly so that it joins the metal or plastic pieces. This technique is used where the metal or plastic is thin and where the joint does not have to be very strong. It is ideal for joining aluminium or even thin sheet plastic.

1. The two pieces of plastic or aluminium are drilled to a size slightly larger than the rivet

2. The pop rivet is passed through both holes in the sheet plastic / aluminium.

3. The rivet pliers are pushed on to the pin of the rivet and the handles are pulled together. As this happens the pin head is pulled into the rivet and the end of the rivet is expanded. Eventually the pin will break off leaving the rivet permanently fixed in position holding the two pieces of plastic / aluminium together.