Hatem Elaydi, IUG, Spring 2017, Chapter 28Д§ Dr. Without this gas, the hot metal would combine with the oxygen in the air, and this would weaken the weld. When heated, this produces a shielding gas, which protects the molten metal from oxygen. The rod is also coated with a material called flux. The welding rod is therefore consumable -it is used up. The electrode consists of a welding rod вЂ“ a stick of metal of the same type as the workpiece вЂ“ which provides filler. The heat from the arc melts the base metal. Shielded metal arc welding (SMAW), generally called arc welding or stick welding, involves striking an electric arc between the workpiece and an electrode вЂ“ an electrical conductor. Hatem Elaydi, IUG, Spring 2017, Chapter 28Д¦ B. It can also occur in the heat-affected zone (HAZ) -the material close to the weld pool which was subjected to high temperature, and was modified by the heat. This problem occurs after welding, as a result of contraction in the weld zone (or fusion zone) -the area that was the weld pool. This is force- for example, tension- which is 'trapped' around the joint. Hatem Elaydi, IUG, Spring 2017, Chapter 28ДҐ One problem in welding is discontinuity, where joints are not completely solid. This is new material, of the same type as the base metal, which is melted into the weld pool - the molten metal at the joint during welding. For example, copper can be welded to steel. It is possible - though more difficult - to weld certain dissimilar materials. Hatem Elaydi, IUG, Spring 2017, Chapter 28Д¤ Welding is usually used to join components of the same base metal- that is, the metal the components are made of. When the joint fuses, material from each component is mixed together, joining to form a solid weld. The heat melts the edges of the components being welded together, and once the material has become molten (liquid), fusion occurs. Welding Welding means permanently joining two pieces of material by heating the joint between them. Hatem Elaydi, IUG, Spring 2017, Chapter 28ДЈ A. Hatem Elaydi Engineering Technical English Islamic University of Gaza March 2017Дў Outlines Welding Common gas and arc welding techniquesДr. Presentation on theme: 'Chapter 28: Non-mechanical joints 1'- Presentation transcript:Дr.

Mechanical joints examples