Office Chair Welding and Polishing

The welding and polishing of office chairs should follow standardized procedures to ensure structural stability and a smooth surface. The process is divided into three parts: welding, polishing, and safety precautions:

I. Welding Process

1. Material and Tool Preparation

   • Material Selection: Preferably use galvanized square tubes or ordinary carbon steel square tubes with a thickness of ≥1.5mm. The commonly used size for chair legs is 20×40mm, for the seat frame is 30×50mm, and the size of the backrest frame should be adjusted according to the design.
   • Tool List: Equip with a 220V household electric welder, angle grinder, E4303 welding electrodes, tape measure, marking pen, wire brush, protective mask, and insulating gloves, etc.
   • Cutting Requirements: Cut the square tubes according to the design dimensions. The length of the chair legs is generally 40-45cm, the seat frame is 35-40cm long and 30-35cm wide, and the backrest frame can have a reserved inclination angle.

2. Frame Assembly and Positioning

   • Seat Base: Weld short square tubes into a rectangular frame and add 2-3 horizontal reinforcing bars inside to enhance load-bearing capacity.
   • Chair Leg Installation: Weld the chair legs vertically at the four corners of the seat frame. Use a square ruler to calibrate the perpendicularity to ensure that the heights of the four legs are consistent and prevent the chair from wobbling.
   • Backrest Welding: The backrest square tubes need to be bent or installed at an inclination. After reserving an inclination angle of 10-15cm, weld them to the rear side of the seat frame to ensure ergonomic comfort.

3. Welding Operation Specifications

   • Surface Treatment: Before welding, clean the rust and oil stains on the contact surfaces to ensure they are flat and free of impurities.
   • Welding Parameters: Use a flat welding position, control the current at 80-120A (adjust according to the thickness of the square tube), and keep the welding electrode at a 30-45 degree angle to the welding surface.
   • Quality Requirements: The weld seams should be continuous and full, avoiding defects such as slag inclusions and porosity. After welding, gently tap the weld slag to check the quality.
   • Material Adaptation: For galvanized square tubes, it is recommended to use carbon dioxide gas shielded welding to reduce the harmful fumes generated by the evaporation of the galvanized layer.

II. Polishing Process

1. Initial Polishing

   • Use an angle grinder to polish the protrusions and burrs of the weld seams to make the surface smooth and free of sharp edges.
   • Use 80-grit sandpaper to remove coarse weld slag, and then use 200-grit sandpaper for fine polishing to avoid scratching the subsequent coating.

2. Calibration and Inspection

   • Shake the chair to test its stability and reinforce the loose positions by welding.
   • Correct any frame misalignment to ensure that the overall shape is square and free of deformation, avoiding an impact on the user experience.

3. Surface Treatment

   • Galvanized Square Tubes: Can be directly painted with anti-rust paint or varnish to protect the galvanzed layer.
   • Ordinary Carbon Steel Square Tubes: Need to be painted with an anti-rust primer first, then with a topcoat, or directly undergo spray coating to enhance corrosion resistance.

III. Safety Precautions

• Ventilation Requirements: Welding should be carried out in a well-ventilated environment to avoid inhaling fumes.
• Anti-electric Shock Measures: Do not weld on wet ground to prevent the risk of electric shock.
• Cooling Treatment: After welding, wait for the weld seams to cool completely before touching the finished product to avoid burns or structural deformation.