Which tool is typically used for joining metal parts through welding?

A spot welder is specifically designed for joining metal parts through the process of welding. This tool uses electrical resistance to generate heat and fuse together overlapping metal surfaces, making it particularly effective for tasks such as joining thin sheets of metal in manufacturing and repair work. Spot welding is widely used in industries, including automotive and metal fabrication, due to its efficiency and the strong bonds it creates.

The other tools mentioned do not serve the purpose of welding. A masonry pointing trowel is used for shaping and applying mortar in brick and masonry work, while an emery grinding wheel is employed for grinding or finishing metal surfaces rather than joining them. An adjustable wrench, although a handy tool in mechanical work, is used for gripping and turning nuts and bolts rather than performing welding tasks. This differentiation underscores the specialized function of the spot welder in metal joining applications.