(a) Cite advantages of forming metals by extrusion as opposed to rolling. (b) Cite some disadvantages.

There are several advantages of forming metals by extrusion as opposed to rolling: 1. Complex shapes: Extrusion allows for the production of complex cross-sectional shapes, which might be difficult to achieve through rolling. 2. Seamless products: Extrusion process yields seamless products, whereas rolled products may have seam defects. 3. Grain structure: Extruded products have a better grain structure as it undergoes continuous deformation, leading to improved mechanical properties. 4. Surface finish: The extrusion process generally provides a better surface finish as compared to rolling. 5. Production rate: Extrusion tends to have a faster production rate, especially when producing small-sized components.

Despite its advantages, there are also some disadvantages of forming metals by extrusion: 1. Extrusion force: Extrusion process requires a higher force to push the material through the die, which can be energy-intensive. 2. Material limitation: Not all metals can be easily extruded, particularly those with limited ductility, such as many high strength-to-weight ratio alloys. 3. Die wear: Due to the high forces and material flow, dies used in extrusion can wear out quickly, leading to higher maintenance and tool replacement costs. 4. Limited length: The length of the extruded product is limited by the size of the extrusion press and the complexity of the cross-section. 5. Heat treatment: Some materials require post-extrusion heat treatment to achieve desired material properties, which adds an additional step to the manufacturing process.