Desoldering of Office Chair Tray

For desoldering of an office chair tray, it is generally recommended to directly replace the tray. If repair is required, refer to the following steps, but note that there may be stability risks associated with welding.

I. Considerations Before Repair After the office chair tray desolders, direct welding repair is not the optimal solution. After welding, the chair may frequently tilt due to changes in structural stress. Moreover, the high-temperature welding process may damage the air pressure rod's sealing or internal structure, causing the air pressure function to fail. If the tray is made of zinc alloy, welding is more difficult and requires professional equipment to control the temperature; otherwise, problems such as weld embrittlement or porosity may occur. If the tray is severely damaged (e.g., multiple fractures), the repair cost may be close to the cost of replacing it with a new tray, in which case replacement is more economical.

II. Repair Steps (If Persisting with Welding)

1. Cleaning and Grinding Use a soft-bristled brush to remove dust and oil stains from the surface of the tray, focusing on the desoldered area and the surrounding 10 cm range. Grind the desoldered part with 80 - 120 mesh sandpaper to remove the oxide layer and burrs until the metal luster is exposed, ensuring that the welding surface is flat and smooth to prevent impurities from affecting the weld quality.

2. Welding Operation

   • Material Judgment: If the tray is made of zinc alloy, preheat it to 150 - 200℃ (using a hot air gun or baking lamp) to prevent cracks caused by sudden temperature changes during welding; if it is made of steel, skip the preheating step.
   • Welding Tools: Select a welding wire that matches the material of the tray (e.g., zinc-based welding wire for zinc alloy and low-carbon steel welding wire for steel). Use tungsten inert gas (TIG) welding or gas welding equipment and control the current at 80 - 120A (adjust according to the thickness of the tray).
   • Welding Techniques: Use short-arc welding and fix the desoldered part by spot welding in sections to avoid metal deformation caused by prolonged high temperatures. After welding, gently tap the weld with a hammer to release internal stress and reduce the risk of cracking.

3. Post-Welding Treatment Grind the weld with an angle grinder or sandpaper to make it flush with the surface of the tray and avoid sharp edges that could scratch the user. Check the welding area for defects such as porosity and cracks and perform re-welding if necessary.

III. Reinforcement Measures Attach a 3 - 5 mm thick steel plate or U-shaped steel bar to the weld and fix it with M5 bolts to increase structural strength. If the connection between the tray and the air pressure rod is loose, add metal gaskets or use thread-locking adhesive for reinforcement.

IV. Alternative Solution Recommendations If welding conditions are not available, you can directly purchase a tray of the same model for replacement (the price is approximately 50 - 200 yuan) or contact the manufacturer for repair services. During daily use, avoid frequent rotation or overloading (it is recommended that the load capacity be ≤120 kg) to extend the service life of the tray.