Office Chair Backrest Assembly

The assembly of an office chair backrest should be carried out according to standardized procedures, with the core steps divided into tool preparation, main body installation, and functional debugging.

I. Tool and Accessory Preparation

1. Tool Selection: Choose tools based on the type of chair. For conventional assembly, a Phillips screwdriver or an Allen wrench is required (some chairs come with a tool kit). If it is a pneumatic lifting chair, deflate and reduce the pressure first to avoid the sudden popping out of the gas rod during installation, which could pose a safety hazard.
2. Accessory Verification: Ensure that all accessories are present, typically including a backrest bracket, a screw pack (containing M6 Phillips screws, C/D screws, etc.), and an instruction manual. The screw specifications must strictly match; for example, an M6 screw may have a length of 25mm, and the choice should be based on the depth of the installation holes.

II. Main Body Installation

1. Modular Installation (Mainstream Method):
   • Align the groove at the bottom of the backrest bracket with the metal rail at the back of the seat cushion and press down vertically until you hear a 'click', indicating that the snap-fit is fully engaged.
   • Use four M6 Phillips screws to tighten the fixing holes on both sides of the bracket from the bottom of the seat cushion upwards. Tighten them in a diagonal sequence in multiple passes (e.g., tighten the top-left and bottom-right first, then the top-right and bottom-left) to avoid tilting the bracket due to unilateral force.
2. Other Installation Methods (for Special Structures):
   • If the backrest needs to be connected to the armrests, first insert both sides of the bottom of the backrest into the armrest installation positions on the seat cushion, and use two C screws to fix the bottom of the backrest from the bottom of the armrest brackets. Then, align the installation holes at the back of the backrest with those on the seat cushion brackets, and use two wrenches to lock and fix them with D screws (one person needs to hold the backrest while the other tightens the screws).
   • Some chairs use four M6*25mm screws to directly connect the armrests and the backrest. Ensure that the screws penetrate the thickness of the armrest brackets and the side panels of the backrest, and check the stability of the connections after tightening.

III. Functional Debugging

1. Tilt Function Test: After installation, manually adjust the tilt angle of the backrest and check whether the locking mechanism at the connection between the gas rod of the five-star base and the backrest is flexible. If the resistance is too high, it may be due to a lack of lubrication in the bracket slide rails, and a small amount of silicone grease should be applied (avoid using greasy lubricants to prevent dust adsorption).
2. Lumbar Support Adjustment: For models with lumbar support, adjust the support plate to the position of the third and fourth lumbar vertebrae (approximately level with the navel) and fix it by rotating the lumbar support adjustment knob or sliding the snap-fit.
3. Stability Check: After installing a bow-frame structured backrest, the front-to-back rocking amplitude should be less than 2cm. If it exceeds this range, all screws need to be retightened, and it should be checked whether the snap-fits are fully engaged.

Precautions: Avoid over-tightening the screws during installation to prevent stripping; if the hole positions are misaligned, realign them before fixing and do not force the installation.