Office Chair Manual Prototyping

The process of manual prototyping for office chairs can be referred to the following steps:

1. Tool and Material Preparation
   Prepare tools such as an oily pen, ruler, scissors, pattern pins, dot punch, tape dispenser, as well as materials like transparent film (0.1 mm thickness), wide tape (8–10 mm), and cardboard (0.5 mm density board). Ensure tool precision; for example, use a ruler for measuring lines and sharp scissors to avoid rough edges during cutting. Material selection should meet durability requirements, such as the transparent film needing flexibility to conform to curved surfaces.

2. Drawing Contour Lines
   Lightly sketch the outline and key points on the foam surface using an oily pen, avoiding sharp turns with R-angles less than 5 mm (which can easily cause film tearing) and overly smooth areas with R-angles greater than 10 mm (which can result in blurred lines). Key points include seat edges, turning points, and symmetry axes, ensuring lines are clearly visible.

3. Film Application and Fixation
   Lay the transparent film over the foam and secure it around the edges with pattern pins, ensuring both pieces of material are oriented in the same direction (to avoid deformation due to texture differences). Leave a 1–2 mm margin between the film and foam to accommodate surface undulations. Apply even pressure during fixation to prevent local wrinkling.

4. Replicating Contour Lines and Trimming Film
   Redraw the foam contour lines with an oily pen to ensure seamless alignment between the two film pieces. When cutting along the outer edge of the lines, leave an extra 1 mm margin to prevent the film edges from lifting when attached to the cardboard (due to potential small burrs on the cardboard edges) or from being overly loose (excess margin causing sewing difficulties).

5. Film Attachment and Cardboard Trimming
   First, secure the trimmed film corners to the cardboard, then use small tape segments approximately 30 mm long to attach the film gradually, avoiding stretching that could distort the lines. Trim excess cardboard according to the sewing margin (usually 3–5 mm), widening the margin appropriately (e.g., 5–8 mm) in areas with significant curvature to prevent tearing during sewing. Use a dot punch to create notches (about 0.5 mm deep) at key points for easy alignment later.

6. Point Alignment and Pattern Labeling
   Align the edges of the two pieces to be sewn and compare the points stitch by stitch according to the needle path, correcting any misalignments immediately by adjusting the film. Print labels in a unified format, including information such as vehicle model, pattern name, quantity, material thickness, grain direction, accessory specifications, and sewing method, ensuring traceability and standardized production.