Correct manual arc welding

I. Pre-welding Preparation
Equipment and Material Inspection:
Welding machine: Check that the casing, cables, and welding tongs are in good condition, and ensure reliable grounding.
Welding rods: Select the appropriate type and diameter of welding rods according to the base metal material (e.g., carbon steel, stainless steel) and joint type. Acidic welding rods need to be dried at 150°C for 1 hour, and low-hydrogen welding rods need to be dried at approximately 350°C for 1 hour. After drying, place them in a heat-preserving container (≥120°C) and take them out as needed to prevent moisture absorption.
Workpiece: Clean the bevel and the area within 20mm on both sides of the bevel, removing oil, rust, water stains, etc., to expose the metal luster.
Assembly and Positioning:
Assemble the workpiece according to the drawings, controlling the assembly gap (e.g., 3.2-4.5mm).
Perform tack welding on the back of the workpiece. The weld length should be ≥40mm, and the thickness should be moderate to prevent welding shrinkage and deformation.
Check that the bevel angle, root face size, etc., meet the process requirements.
II. Welding Operation
Arc Ignition:
Scratch method: Lightly scratch the surface of the workpiece with the end of the welding rod, and quickly lift it 2-4mm to ignite the arc.
Direct contact method: Position the welding rod vertically against the workpiece, lightly touch it, and then quickly lift it to ignite the arc.
The first arc ignition can be practiced on a test plate before formal welding.
Welding Technique:
Maintain a constant angle between the welding rod and the workpiece surface (approximately 75°-80° for flat welding, and tilted downwards 5°-10° for vertical welding).
Use straight, zigzag, or crescent-shaped welding techniques, controlling the arc length to 2-4mm, avoiding excessively long or short arcs.
During welding, observe the shape of the molten pool and the weld pool to ensure that the slag floats sufficiently and the weld bead is well-formed.
Joint Treatment:
Prepare the joint when the welding rod has 40-50mm remaining. Before extinguishing the arc, fill the crater, and pull the welding rod back 10mm to extinguish the arc.
After changing the welding rod, ignite the arc 5-10mm in front of the molten pool, quickly pull it to the molten pool, and adjust the welding rod angle to ensure good fusion. III. Post-Welding Treatment
Arc Termination:
The end of the weld seam must be filled to prevent crater cracks. This can be achieved by using methods such as circular motion, repeated arc breaking, or back welding.
Cleaning and Inspection:
After the weld seam cools, remove the slag from the surface of the weld with a hammer and inspect the weld's appearance quality (e.g., reinforcement height, width, undercut).
If necessary, perform non-destructive testing (such as X-ray or ultrasonic testing) or destructive testing to ensure the internal quality of the weld is satisfactory.
IV. Key Points
Safety First: Wear a protective face mask, gloves, and work clothes throughout the process to prevent arc burns and scalding.
Parameter Matching: Welding current, voltage, and speed must be adjusted according to the electrode diameter, material, and position, and kept stable.
Environmental Control: Avoid welding in windy or humid environments to prevent defects such as porosity.