Office Chair Bottom Production
The production of an office chair bottom mainly includes three core processes: base mold design and manufacturing, base injection molding process, and bottom component assembly.
Base mold design and manufacturing is the foundation for producing office chair bases. The mold typically adopts a five-claw or six-claw structure, primarily made of nylon PA66 reinforced with glass fibers. During the design phase, a dual-track approach of 'Finite Element Analysis (FEA) + dynamic simulation testing' is employed to optimize parameters such as the number of claw arms, arm length, and curvature, ensuring proper load distribution and rotational stability. For example, adjusting the angle between the claw arms and adding reinforcing ribs can enhance stress dispersion efficiency and resistance to deformation. In the manufacturing phase, high-temperature molten plastic raw materials are injected into a preset cavity and cooled and solidified within 8-12 seconds, forming a base with a central shaft hole, claw arms, and reinforcing ribs. The mold design tolerance must be controlled within ยฑ0.01mm, with manufacturing precision reaching the micrometer level, to ensure a base lifespan exceeding 1.2 million cycles (compared to the industry average of about 500,000 cycles).
Base injection molding process requires strict control over materials and procedures. The raw material must be nylon PA reinforced with glass fibers (GF) to ensure adequate strength and hardness. Before molding, the raw material must be preheated and dried to prevent defects such as silver streaks and bubbles caused by residual moisture. The injection molding process consists of five stages: feeding, plasticization, injection, cooling, and demolding. Quantitative feeding ensures stable operation; the plastic is heated in the barrel to a viscous fluid state; the injection stage involves filling the mold, maintaining pressure, and allowing backflow to complete melt filling; after the gate freezes, a cooling medium is introduced to release pressure; the molded part is then ejected using an ejection mechanism. Post-processing of the parts further stabilizes or enhances performance through heat treatment and humidity regulation processes.
Bottom component assembly involves integrating the base with other components to form a complete structure. The core components include: a gas spring (lift column) installed at the center of the base, enabling height adjustment through high-pressure nitrogen, with an outer layer wrapped in anti-static plastic; a five-star base (support frame) with a radial five-claw structure, typically made of nylon or metal (aluminum alloy/steel), capable of supporting loads over 120 kilograms; casters (universal wheels) mounted at the ends of the five-star base, with standard models made of hard PVC and premium models made of soft PU, enabling 360ยฐ silent rotation; and a support plate (seat cushion connector) located at the top of the gas spring, connecting the seat cushion to the lifting mechanism, with some designs incorporating a seat tilt adjustment gear set. During assembly, workers place the base upside down on a fixture and sequentially install components such as casters, gas cylinders, and tilt mechanisms, securing them with bolts and cables. For example, a pneumatic press is used to secure the casters, and machines firmly attach the gas cylinders and tilt mechanisms to the base to enable forward and backward tilting functionality.
