Office Chair Welding Methods

Common welding methods for office chairs include Metal Active Gas Welding (MAG), Tungsten Inert Gas Welding (TIG), and Manual Metal Arc Welding (MMAW). The specific choice depends on the process objectives and structural requirements.

I. Common Welding Processes and Their Applicable Scenarios

1. Metal Active Gas Welding (MAG)

   • Principle: Uses a mixture of 80% argon (Ar) and 20% carbon dioxide (CO₂) as shielding gas. An electric arc heats the welding wire and base material to form a weld.
   • Advantages: Moderate penetration (2-4mm), high deposition efficiency (approximately 5-8kg per hour), uniform weld formation, and low overall cost. Suitable for complex office chair structures requiring mass production.
   • Application: Welding critical load-bearing parts such as chair frame five-leg connections to risers and table legs to crossbeams. Must meet a tensile strength of ≥380MPa (90% of the strength of Q235 steel base material).

2. Tungsten Inert Gas Welding (TIG)

   • Principle: Uses pure argon as shielding gas, with a tungsten electrode. An electric arc melts the base material and filler wire to form a weld.
   • Advantages: Excellent argon shielding effect, high weld purity, suitable for precision welding of ultra-thin parts (0.8-2mm).
   • Application: Local repair of exposed decorative parts (e.g., armrest trim strips). Must meet a tensile strength of ≥280MPa, and the weld must achieve a 'mirror-grade' standard (no undercut, no porosity, reinforcement of 0.8-1.2mm, and width deviation ≤0.5mm).

3. Manual Metal Arc Welding (MMAW)

   • Principle: An electric arc between the electrode and base material melts the electrode coating and base material to form a weld.
   • Limitations: Requires frequent electrode replacement, relies on the coating for molten pool protection, prone to burn-through on thin-walled parts, poor weld formation, and has been gradually phased out.

II. Core Objectives of Welding Process Plans

1. Strong Connection: Critical load-bearing welds must ensure tensile strength compliance through process parameter control (e.g., current, voltage, welding speed) to avoid structural failure.
2. High Aesthetics: Exposed welds must undergo post-welding processes such as grinding and polishing to eliminate defects and meet appearance quality requirements.
3. Easy Operation: Standardized parameter ranges (e.g., MAG welding current of 180-220A, voltage of 22-26V) and auxiliary tooling (e.g., positioning fixtures) are designed to reduce reliance on welder skill. Intermediate welders can master the process after 3 days of training.

III. Specific Operation Example (Square Tube Chair Welding)

1. Cutting and Bending: Cut square tubes according to design dimensions (e.g., cut two 60cm lengths of 3x3 square tube, make a 5mm notch at 26cm for bending and welding; cut two 24cm lengths of 2x2 square tube and align for welding).
2. Welding Reinforcement: Use multi-pass MAG welding for the connection between the chair frame five-leg and riser to ensure penetration and strength; use TIG welding for spot fixing of decorative strips followed by grinding.
3. Detail Handling: Control weld reinforcement and width deviation. The height from the ground must comply with ergonomic standards (e.g., chair leg height from the ground of 40-45cm). Strengthen welding at the backrest attachment point.