The process of joining together two pieces of metal by fusion. Intense heat is applied by an oxyacetylene torch in gas or oxacetylene welding, and by electrical means in arc welding. Sometimes a filler rod is melted along the joint, in the process known as brazing. The direct welding of two pieces by combining the molten edges is called fusion welding. It is done at much higher temperatures than soldering and results in stronger, more durable joints. It is used in making direct metal sculpture and comes under the general term of assembly - as opposed to carving and modeling.