1. The selection of welding rod diameter in manual arc welding is primarily influenced by several factors: the thickness of the base material, the type of bevel, and the welding position (such as flat welding, vertical welding, horizontal welding, and overhead welding).
2. In flat welding positions, a relatively larger welding rod diameter can be used; however, for overhead positions, a smaller diameter is typically chosen to better control the molten pool.
3. For welding thin plates, a vertical pure acid welding rod with a diameter of 2.5 millimeters is usually preferred; for medium-thickness plates, rods with diameters of 3.2 millimeters or 4.0 millimeters can be selected; and for thick plates, a vertical pure acid rod with a diameter of 5.0 millimeters is necessary.
4. When performing initial welds, using a rod with a diameter of 2.5 millimeters is generally recommended as it can provide a better welding result.
5. For fillers, selecting a welding rod with a diameter of 3.2 millimeters or 4.0 millimeters can provide adequate filler material.
6. For cover pass welding, a rod with a diameter of 4.0 millimeters or 5.0 millimeters should be chosen based on the thickness of the plate to ensure the appearance and quality of the weld joint.
